Landracing Forum
Bonneville Salt Flats Discussion => Build Diaries => Topic started by: roflhat on November 04, 2019, 05:03:52 PM
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Hi everyone,
starting a thread for my P-PC 100cc build. Trying to keep it both simple and cheap, I've always wanted to attempt a record at Bonneville so this is hopefully what I'll be doing it on.
Bought the bike last month on ebay, and by a stroke of luck a friend was down in Wales with a van and was able to collect and take it up the Isle of Lewis for me free of charge. Here's the bike as I got it, hasn't run in likely over a decade but is in nice overall condition
(https://iili.io/HFEicg.jpg)
Stripped a few bits off, indicators, luggage rack etc. Some other jobs, front brake was locked on, changed the front wheel bearings.
(https://iili.io/HFEsSa.jpg)
Allowed to change the handlebars so I got a clubman style set, needed some sanding to get the new throttle roller on there
(https://iili.io/HFEQHJ.jpg)
How the bike sits at the moment, haven't had it running yet still waiting on a couple parts.
(https://iili.io/HFEZAv.jpg)
Sure I'll have plenty questions as I go along, any input welcome
Still need to get new tires, wheel balance, steering damper, a kill switch with cord
cheers
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Great-looking little bike!
I'm not a bike guy (although I had a CB100) -- what year is it?
What class would it run at Bonneville? And what's the record?
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Good Luck! I hope you get to come over and set a record. Which Bonneville sanctioning event are you planning for? SCTA (Speedweek, etc) or AMA (BMST)? I see that the SCTA record is open so that is guaranteed. BMST is 52.7 MPH. Easy-peasy! What are your plans to make it go fast?
Keep posting.
Don
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Also- make sure you measure bore and stroke and verify the engine is indeed stock. There are overbore limits that could possibly disqualify you.
Don
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.... I see that the SCTA record is open so that is guaranteed. BMST is 52.7 MPH. Easy-peasy! What are your plans to make it go fast?
Keep posting.
Don
Suppose to run 70+ stock...
https://www.cmsnl.com/gp100_model13377/info/
Good luck with the bike and sure hope you make it over,
Sumner
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Thanks everyone! It's a 1980, class allows pre 1981
The AMA record was 35.949mph although I believe it was beaten in 2018, around 50mph as Don says.
Original top speed of the GP100 is meant to be around 70mph but I will have to see what it does now. Going to rebuild the engine, make sure everything is in new condition. Not allowed to do too much for this class, going to fit a narrower front tire, then just play with the jets and different sprocket sizes. I've heard you lose 20% ish power and compression at Bonneville so will no doubt have to adjust again if I get there.
Spoken to George Kronkite who set a record on a Suzuki TS400, after all his tuning his record speed was identical to the original top speed of the bike. So around 70mph would be a nice target for me
Will also be going on a diet myself, I'm around 75kg at the moment.
Not sure whether to go for Speedweek or BMST, from what I hear Speedweek is a great spectacle with awesome machines but busy. AMA sounds good too, and I like the idea of having a target speed to beat
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Roflhat,
SCTA (Speedweek) does not have a Production Classic class, only AMA (BMST). At an SCTA meet, with the bike your building/planning, you would have to run in Production Production . The current record is 82.8 mph set in 2003. AMA rules are online. SCTA rule book can be purchased for $10 (go to the home page of this forum, then SCTA) Welcome to the LSR family. Hope this helps..
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The low handlebars and narrow tire are good for a bit of speed. Remove the turn signals of course. Get tires as smooth as possible, not knobby ones. Run as high tire pressure as possible. Make sure the brakes do not drag. Wear tight fitting leathers. Practice your tuck and get as low as possible. Elbows and knees in.
Also get a NON O-ring chain as the O-ring type eats HP.
Don
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Thanks for all the help and information, I am writing this all down in a file as I plan this project.
Looks like I will aim for the AMA event, most likely 2021.
Does anyone know the differences between P-PC and P-CG? I've just been looking at the rules and can't see much of a change in the rules there. Both records are held by the same guy, on probably the same bike or at least the same make.
I don't own any leathers at the moment so will do plenty of reading before investing, ideally want almost a lycra suit!
Is there a rule of thumb as to how narrow a tire I can fit on my rims? standard front tire is 2.50r18, rear 2.75r18
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Biggest difference between PC and CG is that a CG motor can use any fuel delivery (bigger carbs, switch to fuel injection), while PC has to stay with stock carbs.
Leathers - a road race style suit with lycra panels and perforation is legal at BMST. But if you ever plan to run at an SCTA event the suit cannot have any perforations. You can usually pick out an SCTA racer by their very expensive, vintage looking custom Vanson or Bates leathers. You don't need new leathers, but you need good quality, protective leathers. The salt is very unkind to skin. Dainese, Alpinestars, Spidi etc. one and two piece suits will work.
Re tire size, manufacturers will often have a chart that specs the minimum and maximum rim size for a tire. I've had good luck finding Heidenau tires in skinnier sizes. They are mostly rated for speeds below 112 mph, but that will not be an issue for you. I run a Heidenau K40 2.50-18 front on a 1.4" rim.
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75 kg... what's that in Stones? OK just kidding...
Well you have a goal... you can set an AMA record or you can try to be the fastest 100cc production bike in the world...
Ya know if it came from the factory with a fairing... it would be legal....
Don't know if any did, just clarifying the rules
Have fun :cheers:
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Yes, Like Stainless said, you can go for the American Motorcycle Assn record at BMST, or go to BMST and get the record certified by by the FIM, which is International. FIM has specialized rules so check that out too. SCTA is regional, not national or international.
Don
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Are you aloud to tune the moter and use an expansion chambrer in your class ?
You can do a lot to thise little gp disc valve moters for allmost no money,
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hello ROFLHAT
welcome.
The build should be a lot of fun. Good luck with it. The BMST event is AMA and FIM sanctioned. You would just need to choose which sanctioning body you want to race under. AMA rules and regs are linked under the BMST website, I am not sure about the FIM rules, but there are some differences so check out which are relevant to you. FIM is a bit more critical I think its fair to say. Speedweek is certainly more of a spectacle as you say, but BMST is a bike only event so you will find the course might be a lot less abused and dare I say it, in better condition. Plus the waiting times will be less at the BMST event.
Whichever event you choose to race at, good luck with the build, it'll be very interesting to see how it goes.
Cheers
John
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Thanks for all the replies, might look into doing the P-CG at the same time using one of these Smartcarbs.
Looks like I'll do the BMST event, will keep an eye out for a decent set of used leathers. Going to have a measure of the rims and then look further into tires too. Think I'm pretty limited to what I can change aerodynamically on the bike, but will try and make sure my helmet and my own positioning on the bike is decent
Not allowed to run an expansion chamber, the whole bike has to pretty close to standard, can tune the engine a wee bit but all needs to look standard
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Aiming for BMST 2021, been doing bits and pieces on the bike. New fuel line, fuel tap, got a steering damper and kill switch to fit. Still trying to get hold of the tires I want, think I've found a source though. Need to tape the headlight too, it'll look the part then. Almost ready to try get it running, then it'll be doing a couple things to the engine. Got another carb to use for the CG class record. Got some polishing done on the mudguards, came up pretty well. Looking at some Alpinestars leather, going for used ones. Then gloves and boots.
(https://iili.io/HLSHTG.jpg)
(https://iili.io/HL8yps.jpg)
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Looking good! I crunched some numbers and at the rated 12hp it looks to be competitive in production. As I pull stuff off my bike from last year and lament the amount of corrosion in spite of a very through cleaning after the event I'll suggest you think about waxes, anti-corrosion sprays, etc. while you have the bike going together. Worst places for salt buildup are front and underside of the motor, under the front end of the swingarm and everything around the rear wheel. Looks like you might want to get fresh paint or powdercoat on the swingarm to protect it.
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It was up there with the fastest bikes of its capacity back in the day so should work alright.
(https://iili.io/Htoi6F.jpg) (https://freeimage.host/i/87953799-178434953582255-9104885837757153280-n.Htoi6F)
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Been trying to start the bike, has fuel, spark and compression but isn't going yet. Going to go over the timing next. Looks good though!
(https://iili.io/HDgl4f.jpg) (https://freeimage.host/i/87815251-216671862787540-1634169879999283200-n.HDgl4f)
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I find 2-strokes very sensitive to gas fouling of the spark plug. Make sure you have some extra plugs on hand. I've also actually used a propane torch to make sure there's no gas down in the plug on my chain saws and weed whackers - - Dodge hard things to start and keep tuned up! My Ossa (piston port timing) requires absolute flooding of the carb (IRZ carb, like Amal) including tilting the bike back and forth to get some fuel into the motor to get it to light up. Bridgestone (rotary valve) is just the opposite, as flooding will prevent it from starting easily.
Good luck, it looks great!
Tom
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Have not looked at the classic rules but production bikes just need to appear stock from outside. Internal moids allowed, better piston, thinner gaskets, coatings , porting etc
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When was the moter last taken apart ? Old dry crankshaft oilseals could be a problem and can suck/blow air on the ignition side and the same for gearbox oil on the transmission side, and will lack primary compression its imperitive that these are in good condition or youll never be able to tune the moter properly. Go little gp. A shame you cant use a expansion chamber...these moters are very tuneable.
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In theory you can use an expansion chamber if you can get the dimensions within the stock exhaust. The muffler is pretty big, so it should be possible to split the pipe, add a chamber and seal it up again and either polish the heck out of it, or get it re chromed. You might even be able to get away with just leaving it very dirty. The rule is "no visible" modifications, so as long as dimensions, outlets etc. match, then you should be good to go.
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"no visible modifications" can be liberally interpreted if you ask nicely. The canisters on Nancy's bike got opened up, emptied and re-welded to original appearance.
Well, not very original. The inspector saw the ugly buggered-up welds and questioned them and I replied that "It must have been the Kawasaki factory's new guy's first day on the exhaust welding line and he used coat hangers instead of rod" - and got away with it!
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Cheers everyone, going to get the timing to stock and go from there.
The motor will be getting a full rebuild, and a bit of a tune at the same time. I'd actually thought of that very idea with the exhaust, thought it was a bit cheeky but I might look further into it now! Want to get the maximum out of it. Also thinking of going for the P-AG class, from what I can gather thats similar to P-PC and P-CG anyway but I'd be allowed a proper expansion chamber and a bigger carb?
Does anyone know if I can go for the P-P record even though it's a classic bike? potentially 5 record classes I could enter
Thinking
P-PC - standard(ish)
P-P - as above?
P-CG - as above but bigger carb
P-AG - as above but also expansion chamber (not 100% sure if this class exists for 100cc)
P-AF - as above but any fuel
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Modifing the exhaust visably ( chambers) puts you in "M" modified class
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Modifing the exhaust visably ( chambers) puts you in "M" modified class
I thought the M designation was for the frame being modified? does the exhaust come under frame?
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I thought the M designation was for the frame being modified? does the exhaust come under frame?
Yes. AMA Bonneville supplementals, page 29 - Production (P) Class frames
Production class motorcycles
shall not be modified from original equipment at time of
manufacture. e.g., frame, forks, gas and oil tanks, seat, front and rear
lighting, fenders, wheels, brakes, air intake box and (unmodified)
exhaust system.
Section 5.D., page 32 - Modified frames
EXHAUST AND MUFFLERS
Length of exhaust/muffler assembly shall not extend past the rear
edge of the rear tire. It must be sufficiently anchored.
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About 45 years ago my friends cut apart Susuki 500 Titan mufflers and put expansions chamber inside. Then they took apart the engine and did major work to decrease the crankcase volume and increase the lower end compression ratio. They put a six speed gear cluster in it from another suzi, as I recall. It was for an AFM production racer. The work that went into it to keep it looking OEM was amazing. It would have been a lot easier to make a modified bike.
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Ah ok, thanks for the clarification!
Liking this exhaust idea, managed to find this online - https://vanguardcycles.wordpress.com/2010/12/03/mini-cafe-sleeper-pipe-project/
I've done a bit of "hiding" modifications before, got a world water speed record in 2018 at Coniston
(https://iili.io/HpWnTJ.jpg)
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Wow! I love that pic. The boat is not even touching the water, it's completely riding on the lower unit. Glad you did not catch a gust of wind!
Don
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Some easy help with engine breathing can be had by making a spacer for the cover over the mouth of the carb. Production bikes need to be somewhat narrow at the footpegs. Keeping the engine side covers tight over and around things make for nice packaging, but this also restricts airflow to the RV intake. Making a cover "gasket" 10 or 12mm thick and painting it side cover silver sounds to be in the spirit of the rules and not too obvious.
Search info on the Kawasaki G31M Centurian. A wicked little rotary valve 100cc MX bike from the early '70s.
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I just realized that the GP-100 is a rotary valve. I cut the rotary valves on my Bridgestone 350 and ported the entrance inlet as well as milling the head. Because I'm running it in MG at Loring, I naturally added bigger carbs (from 27mm to 29mm) and made my own expansion chambers, so it won't qualify for Production. But I think the cutting of the rotary valves made a big difference. The bike runs 113mph in the mile-and-a-half.
If I brought it to BMST, it could run in M-CG and that speed would easily be a record. But spares are so limited, I probably never will.
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This is largely the same unit we got here as the Suzuki Gopher in the early '70s. Parts aren't too tough to find around the world...
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Wow! I love that pic. The boat is not even touching the water, it's completely riding on the lower unit. Glad you did not catch a gust of wind!
Don
Cheers 8-) Hopefully going to Coniston again this year, see if I can top my own record
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I'll have a look at the carb gasket, would certainly be neat to make a sort of spacer that went in there. I guess even a thicker gasket would help some
Taking the bike down to a guy in England who is widely regarded as the best 2 stroke bike tuner in the UK, will blueprint the motor at least, see what he can do with it. Looking at that Bridgestone 350 online, from 95mph original top speed to 113 is a serious improvement, 19% which would see my Suzuki doing 83.3mph going by the quoted top speed of 70mph.
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Who is the tuning guy in uk ?
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Who is the tuning guy in uk ?
Mick Abbey
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Good choice...and he makes some lovely pipes too. (Hydroformed)
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Got the steering damper setup, changed the tires, cush drive and the rear wheel bearings. Still won't run, getting power to the spark plug but not enough to generate a spark. Get one strong blue spark followed by nothing. Changed the coil, HT lead, plug cap, plug, condenser, adjusted points and timing. Ordered a new stator, thinking the condenser isn't getting enough power to keep sparking
(https://iili.io/JH0FHu.jpg) (https://freeimage.host/i/89353693-210525430025709-5284586911288000512-n.JH0FHu)
Think the bike will look a bit better with the white panels for race numbers hiding some of the gap above the rear tire
Bought Alpinestars leathers, proper gloves and boots. Leather are seriously tight, in all the wrong places! But they do fit so they'll do
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Love the bike! Keep grinding...you will get it figured out
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If you bought an old stock condenser it might be leaky. We got my teammate's P-PC Benelli to spark nicely last year by replacing the NOS condenser that he bought to freshen up the ignition with a modern polypropylene capacitor.
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If you bought an old stock condenser it might be leaky. We got my teammate's P-PC Benelli to spark nicely last year by replacing the NOS condenser that he bought to freshen up the ignition with a modern polypropylene capacitor.
It's a new one I got, are you allowed to update parts like that? You do get electronic ignition kits for these
Didn't realise the tires would be so skinny, none of the bikes in the Bonneville photos seem to be running such slim tires. Any reason for this?
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No spark with magneto is super simple to diagnose with a 12v test light, but the first step is even simpler.
Grab the spark plug in your hand, then kick the engine over. If you feel absolutely nothing, the secondary coil has an open in it's wiring or the primary coil has an open in it's winding. If you felt a bit of a tickle, it's time to employ the test light.
First, you must remember that when using the test light in line with the ignition wiring the system will not throw a spark even if everything is working properly. Spark cannot be made while the test light is attached in the electrical circuit.
Remove the points lead from the secondary coil, attach that to one side of the test light lead and the other to ground. When kicking over you should see a bright-ish light pulsing on to off to on etc.
If you see a bright light that does not pulse, the points are not making contact when closed. If you see no light, insulate the contacts of the points and try again. If light now, the points are grounded. If still no light, remove and isolate the wire from the primary coil to the points, try again. The primary coil should put out over 16v dc on a meter. Ohms don't really matter to me, dynamic testing tells all.
If you got a good pulsing light at the secondary coil lead, attach it back to the secondary coil, then perform the same test at the ground side of the secondary coil. You should see a less bright flashing light. If that's the case, re-attach the ground lead to the coil and place the test light between a ground and the spark plug lead. A working system will flash the test light.
I work on a lot of small magneto equipped engines. When I figured this test procedure out diagnosis became very simple, and my Fluke meter got kinda dusty...
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The skinny tires are to your advantage over wider tires. The skinny tires have less rolling friction and less air drag. At your HP, traction will not be an issue.
Good luck with the ignition problem. You will solve it soon.
Don
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Thanks very much for that detailed reply! Didn't use it today but certainly good to have for future reference.
Went to work on the bike today, checked the spark and it was far more frequent. So started going over the wiring, thinking being that something had jiggled into place. Went through all the wires, putting silicone grease on every connection and tightening them up. Getting a healthy blue spark now, and consistently.
Put everything back together and it finally runs 8-)
Doesn't like low RPM at all, above 5k it starts revving on its own so tomorrow I'll clean the carb again.
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The skinny tires are to your advantage over wider tires. The skinny tires have less rolling friction and less air drag. At your HP, traction will not be an issue.
Good luck with the ignition problem. You will solve it soon.
Don
That's what I figured too, just wondering why a lot of the photos I see folk are running standard width tires?
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Thanks very much for that detailed reply! Didn't use it today but certainly good to have for future reference.
Went to work on the bike today, checked the spark and it was far more frequent. So started going over the wiring, thinking being that something had jiggled into place. Went through all the wires, putting silicone grease on every connection and tightening them up. Getting a healthy blue spark now, and consistently.
Put everything back together and it finally runs 8-)
Doesn't like low RPM at all, above 5k it starts revving on its own so tomorrow I'll clean the carb again.
I hope you are using ignition silicone grease and not RTV silicone which attracts moisture.
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The skinny tires are to your advantage over wider tires. The skinny tires have less rolling friction and less air drag. At your HP, traction will not be an issue.
Good luck with the ignition problem. You will solve it soon.
Don
That's what I figured too, just wondering why a lot of the photos I see folk are running standard width tires?
It's hard to find tires in the higher speed ratings in the smaller sizes.
Don
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It's proper electrical grease, we use it on the connections on boats.
Makes sense about the tires, one problem I've now discovered is that the side stand is effectively too long, the smaller tires means the bike is closer to the ground so doesn't lean enough
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It probably does lean enough, just in the wrong direction. muutt
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It might be a good idea to remove the carb and pipe, plug the intake and exhaust, and do a pressure and vacuum test of the engine.
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Being that it's rotary valve, there should be only one crank seal and the casting that covers the RV to be concerned with when leak testing.
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Had a fuel leak from the base gasket, so took the head and barrel off, cleaned up all the surfaces and changed the gaskets. Bit better but still like it was, there's fuel coming from flywheel so probably the crank seal as you say.
Not sure if it can be done with the engine in situ but will find out.
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Usually..yes, you can screw 2 self tapping screws into it and pull, make a tube to fit just a bit smaller than OD Of seal to refit. The trans side probaly is harderned aswell, look at parts lists picture to see if seel has a lip , if it has a lip youll have to destroy seal to get it out, with the new seal you can cut lip off and put in with some polyurathane sealer (sikafix windsreen stuff is good ) not silicon sealer because the petrol will eat it.
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Nice one thanks, want to get it running well before I take it to be tuned. Will be getting stripped down again then anyway but Micks time isn't cheap!
Got another cheeky idea, thinking of getting another seat and replacing the foam with much softer stuff. The idea being when I sit on it it's totally compressed and I sit much lower
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Good idea for the seat.
Looking at your standard pipe that has un upper and lower seam...its just screaming out to be split and a few cones to be inside and then seam welded and sprayed ht black or silver over the "old rusty chrome" that it had..lol
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Good idea for the seat.
Looking at your standard pipe that has un upper and lower seam...its just screaming out to be split and a few cones to be inside and then seam welded and sprayed ht black or silver over the "old rusty chrome" that it had..lol
:wink:
I'm going to have a look at the exhaust too, bought another standard one to cut open, the original is in nice condition so I'll keep that one standard. Would be nice to get it rechromed after the work is done but not sure if it's possible, going to look into it
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How the bike looks at the moment, the numbers aren't on just added them on the photo
(https://i.ibb.co/YpcTXWm/90085997-135195114599995-5283719220520026112-n.jpg) (https://ibb.co/cD6Xwv0)
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Do you have a Haynes manual or anything like that for basic reference info?
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Would be nice to get it rechromed after the work is done but not sure if it's possible, going to look into it
Maybe run the bike on the salt for a week before you worry too much about how good the chrome on the muffler looks. It will definitely look worse after that. :wink:
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Do you have a Haynes manual or anything like that for basic reference info?
Yeh got a Haynes manual for it
Might just use the scruffy exhaust for Bonneville then, save the good one for afterwards
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Does anyone know if you need a license to run at Bonneville? Been riding bikes for years but don't have a license
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Rule M.1 in the 2019 SCTA Rule Book says you must have a current Driver's License. It doesn't specify from where, nor car or motorcycle. I believe some states & countries don't issue separate licenses, and I'm sure the SCTA doesn't know who or where any way.
I've been told you could step off a 100cc bike any time you wanted and not be seriously hurt any way. I'm sure that's just an old wife's tale.
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When I'm inspecting a bike for a new racer I did check for a valid motorcycle endorsement on a valid drivers license, and so did the other inspectors.
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Oh, well.
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so... is this a rule open to the interpretation of the individual inspectors?
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Rule M.1 in the 2019 SCTA Rule Book says you must have a current Driver's License. It doesn't specify from where, nor car or motorcycle. I believe some states & countries don't issue separate licenses, and I'm sure the SCTA doesn't know who or where any way.
I've been told you could step off a 100cc bike any time you wanted and not be seriously hurt any way. I'm sure that's just an old wife's tale.
7.A.1, does specify a motorcycle endorsement.
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Now sure how the licenses work in the US but here it's split into cc categories. I'm planning on doing the basic one which allows me to ride upto 125cc here in the UK. Would that be sufficient for Bonneville on a 100cc?
Had a look through the rules but couldn't see the licenses mentioned, they even mentioned riders from 12 years old being allowed under supervision
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We may have led you a stray, as the rules mentioned are SCTA and I believe you are planning on BMST.
If that's the case, I have no clue.
Don
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Ah ok, from what I gather from the BMST rules you don't actually need a license but I'll get the basic UK one anyway.
Looking at the records it seems there is no P-CF record for the 100cc, does that mean it's an open record? Could go for that too I guess, the rules state "Fuel class motorcycles shall have a positive fuel shut-off activated without the riders hand leaving the handlebars." Anyone know how to achieve this? Can I simply run the fuel line to the handlebars and have a switch there, bleed the fuel through?
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Pingle makes a cable operated spring loaded valve that a lot of us use.
Don
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Pingle makes a cable operated spring loaded valve that a lot of us use.
Don
Cool thanks, looking at it I think I could rig something up, simple cable through the fuel valve that I can pull to put in the off position from the handlebars, think that would be good enough? Can make sure it's sturdy enough
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Got the bike running, not very well so stripped the engine down, changed the crank bearings and seals. Just waiting on a new piston and rings
(https://iili.io/JFiNfa.jpg)
Few other things needed doing, gave the engine a good clean to get 40 years worth of muck off
(https://iili.io/JFiO0J.jpg)
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The salt flats are subject to the weather and it might be a good idea to build for the regulations from the chosen event and the one after that if it is possible to stay over for a few weeks, or to come back again. That would be USFRA legal for the World of Speed if the primary event is BMST.
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Pic in #73 with the engine in bits and a ball peen hammer ...... have you seen the Aussie biker movie 'Stone'?
Kawasaki Zephyr 900's iirc. Anyway - scene it that where the lead characters suitability to infiltrate the gang was assessed and his mechanical skills were referenced; involved said hammer.
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Not sure it'll be possible to attend 2 of the weeks, shame as I'd like to do a lot of runs, and from the programs I've watched that might be difficult seen as there are so many bikes.
Haven't watched that movie but I'll add it to the list, have seen The Worlds Fastest Indian over 30 times now. Was actually going to ask for recommendations on films to watch seen as I've so much time on my hands just now!
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Ended up in hospital today, when I was putting the engine back together yesterday I managed to stick a screwdriver into my index finger. A bit of blood, wasn't too bad but this morning it was painful, throbbing. Over to A&E, got antibiotics and finger all bandaged up but a red line started creeping up my arm. Bit alarming but hopefully sorted now.
Bike is already trying to kill me and I've barely ridden it!
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Ended up in hospital today, when I was putting the engine back together yesterday I managed to stick a screwdriver into my index finger. A bit of blood, wasn't too bad but this morning it was painful, throbbing. Over to A&E, got antibiotics and finger all bandaged up but a red line started creeping up my arm. Bit alarming but hopefully sorted now.
Bike is already trying to kill me and I've barely ridden it!
That sounds like the beginning of a nasty infection. Glad you started on antibiotics.
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Not sure it'll be possible to attend 2 of the weeks, shame as I'd like to do a lot of runs, and from the programs I've watched that might be difficult seen as there are so many bikes.
Not a problem at BMST. You can get multiple runs in by the second or third day. Late in the week people are hot lapping.
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Have you assembled the engine?
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The BMST event almost always thins out a bit through the week, a few days in and you will get your laps in. I always remember a few years ago the lads from Donnington hot lapping on the Wednesday. Are you still on here gents?
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Stone (ca. 1974) was made on a budget and preceded Mad Max - probably inspired it. In Stone is a character called Bad Max - the actor thereof went on to be in Mad Max (as Toecutter I think but I might have made that up).
Good luck with the creeping septicaemia / bacteraemia / Suzi-Q flu thingy.
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What's hot lapping? like back to back runs?
Would like to attempt a record in a couple classes, I'll be more than happy if I get one record!
Engine is pretty much back together, just waiting on a new piston kit and small end bearing.
Red line has slowly creeped back down so hopefully that's the end of it
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Hot lapping - yup, you finish your run and head right back to prestage for another. Regarding multiple records and such, you can make the decision to add another class once you get there. The first time at the event there is a lot to take in and to learn, and you may find yourself plenty busy without committing to multiple record attempts. This will be my third year racing and I'm still chasing down unforeseen issues I would have thought easily solved the first year, e.g., it's my third year and this will be my third different clutch setup.
My first year I got a record. Last year I had to throw in a tired, non competitive engine two weeks before the event. I still had a ball, tried a bunch of new stuff out on the bike and actually learned as much or more the second year as I did the first.
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Sounds ideal, towards the end of Coniston in 2018 I was pretty much the only one still doing runs. Did the most recorded runs ever at one event at 18!
All the classes are close to standard, only minor changes between them and I imagine mostly playing with sprockets and jets.
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Got the bike running nicely now, set up the carb, cleaned the exhaust. Will do until I can take it down to Mick Abbey
(https://iili.io/JCtNhG.jpg) (https://freeimage.host/i/92704375-229236368284007-7030522809675677696-n.JCtNhG)
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That bike looks good. They made nice and comfortable seats back in those days.
If you want to go further without spending big money, there is a lot of info about aerodynamics on a small two stroke bike like that in "The Racing Motorcycle" by John Bradley, Volume 1, ISBN 0951292927. It is about aerodynamic changes to make it go faster with pictures and tables. They got the aero drag coefficient down to 0.274 which is real good and a little bit more than half of what it was when they started.
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Thanks, pretty happy with it now it works.
Is the book for this style of bike or is it proper racing style bikes? Not sure there's much I'm allowed to change much for my classes
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It was a 125 Can Am race bike, I think. It was a long time ago. This is a link to the first part of the article a lot of us read in 1976.https://badcurator.org/resources/Repository/Cycle-Sep76/Motorcycle-Aerodynamics.pdf (https://badcurator.org/resources/Repository/Cycle-Sep76/Motorcycle-Aerodynamics.pdf) The changes would make the bike suited for the partially streamlined classes.
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To be honest I hadn't considered the partial streamlined classes, will have to read up on the rules. There doesn't appear to be a record for MPS-CG in the 100cc class. Not sure if I'm biting off more than I can chew, that would be 6 or 7 different records I'd like to attempt
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Simple front streamlining, like even a frame mounted front fairing, won't do as much as just adjusting your crouch. I put a Norton Dunstall type of front fairing on the Bridgestone last year and only gained 1-1/2 mph (from 113 to 114.5 mph). If you want to try partial streamlining, there are a bunch of things that I can suggest, but they involve completely changing your bike into a full blown race bike.
So keep it simple and remember to keep everything tucked in and get as low as you can on the bike and have fun!
Tom
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What is MPS/CG?
There are hundreds of open motorcycle records to pick from. You've only got to paddle down a mile or two. What's CG? A new category for you 2- (and 3-) wheeled guys to cherry-pick from?
(Just making friends!)
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Stan,
CG is classic/gas (per 1981 motorcycle, NA, 100 cc in this case). It is an AMA class. I believe he plans to race at BMST (not a SCTA event).
Regards,
Don
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Might take a simple cafe racer style front fairing with me, if I have time after trying the other records I could always enter MPS-CG as well.
I have to admit it took me a while to understand all the class designations! Possibly there are too many, I know for the UIM Powerboat records they cut away old records frequently, keeping classes limited for more competition. But if anything they're too far the other way as it's already such a niche sport it limits the nunmber of people that turn up for records week
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Simple front streamlining, like even a frame mounted front fairing, won't do as much as just adjusting your crouch. I put a Norton Dunstall type of front fairing on the Bridgestone last year and only gained 1-1/2 mph (from 113 to 114.5 mph). If you want to try partial streamlining, there are a bunch of things that I can suggest, but they involve completely changing your bike into a full blown race bike.
So keep it simple and remember to keep everything tucked in and get as low as you can on the bike and have fun!
Tom
Which class are you running the Bridgestone in? Do you have photos of it?
I don't know much about them, it's a Bridgestone that holds the P-PC and P-CG records I'm going for, seems to have similar standard performance to my Suzuki
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Had an unfortunate, or rather fortunate incident. Was moving the bike in the shed and the handlebars snapped clean through in my hand. Just as well I wasn't riding the bike at the time.
Took them off and apart, the other side too and welded them up properly
(https://iili.io/JoD5ap.jpg) (https://freeimage.host/i/92990914-1989251514553194-4231963497317007360-n.JoD5ap)
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Simple front streamlining, like even a frame mounted front fairing, won't do as much as just adjusting your crouch. I put a Norton Dunstall type of front fairing on the Bridgestone last year and only gained 1-1/2 mph (from 113 to 114.5 mph). If you want to try partial streamlining, there are a bunch of things that I can suggest, but they involve completely changing your bike into a full blown race bike.
So keep it simple and remember to keep everything tucked in and get as low as you can on the bike and have fun!
Tom
Which class are you running the Bridgestone in? Do you have photos of it?
I don't know much about them, it's a Bridgestone that holds the P-PC and P-CG records I'm going for, seems to have similar standard performance to my Suzuki
Mine is a 350 and I'm only running it at Loring, so Loring records only.
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That's one good looking bike
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It sounds & runs as good as it looks, too! :cheers:
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Anyone know whether I'm allowed to run electronic ignition instead of the standard points? No visible changes to the bike
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Hi, great to see your project coming together, im based in the Uk and have run at Bonneville a few times, and got 2 in the book, let me know if i can assist at all, cheers Ian
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Hi, great to see your project coming together, im based in the Uk and have run at Bonneville a few times, and got 2 in the book, let me know if i can assist at all, cheers Ian
Hi Ian,
thanks very much! what classes do you run in?
Still in fairly early stages but would certainly appreciate if someone could have a look over photos of the bike once it's done to make sure it meets all the regs before I ship it over. That and advice on the shipping itself
Thanks,
Seumas
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Seamus
I am building a G/GL Lakester in the UK - aiming for SW 2021.
Ian provided me with some valuable info on shipping, application forms to DOT and EPA etc and I started collating that but its too far out to be submitting those and I went back to the build.
I am modifying my trailer (and car) to have space in a 20' shipping container (in front for a 'road bike' and on top possibly for a streamlined bike) - into LA - I was planning to create a new thread towards the end of the year for UK folks to contribute knowledge and expertise / lessons learned and see who was up for combined shipping - one 40 footer might be cost effective for several people to crate and load. PM me and I will share what I learned so far.
John
nr. Marlow, Bucks
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Thanks John,
sounds good, will send you a PM just now.
Did the safety wiring on the bike today, handlebar bolts, gearbox fill and drain and the two stroke tank fill.
Does anyone know what octane the fuel for sale at Bonneville is?
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ERC has been the supplier at BMST the past few years. I think the gas classes use 110K, which is 110 octane. They also carry other blends if you run in fuel. Brings cash. Lots and lots of cash. I ran A-8D in a fuel class last time (120+ octane) and I think it was $40 or $50 a gallon. Can't blame ERC, they have to haul all that stuff out there just to fill dinky little motorcycle fuel tanks and they need to cover their costs. It's nice fuel.
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Wow really, good to know I had presumed it would be 93 RON or something. Allows a bit more engine tuning with that octane then, hopefully will run in fuel classes too
Another question, if my bike is set up say for PPC or PCG can I attempt a PAG or PAF record without a modified engine? Or is it a case of you have to run in the lowest possible class?
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Yes, you have to run in the lowest possible class. So you would need to make changes to the bike that would force it into P-AF or P-AG.
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I'll list the fuels that VP plans to have at WF per a flyer I got from Ron Main. You are welcome to look up the various flavors for individual specs.
VP 110
VP C12
VP C14
VP C16
VP MS100
VP TORQ DX Diesel
VP M1
Nitro 100%
We will have a very limited supply.
Please call Bill Lattin for more information 760 533 1932
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Ah ok gotcha, so to enter an F class I can just run an additive in the fuel or a non gas flavour. Will the fuels at BMST be the same as the WF?
Then for an AG or AF classes I guess a billet head would push me into those classes?
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As for running AG or AF, When my wife got 3 records in 2013, one for P-PG two for P-AG and P-AF to alter engine I switch stock 32mm carbs to34mm carbs. in impound however the inspector never looked at what made it qualify as "A" class. 350cc 1972 Yamaha R5
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At SCTA (and AMA) events to ensure gasoline has no enhancements a racer must buy the gas (several octane ratings available) at the actual event. The gas is added to an empty fuel tank and sealed with security tape. This is witnessed by an event official. The tape is to ensure nothing is added by the racer. If the tape is broken you are then by default in fuel class. It is not necessary to actually change the liquid in the tank. But you must do paper work at registration to change class.
Hope this helps
Don
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Ah ok gotcha, so to enter an F class I can just run an additive in the fuel or a non gas flavour.
I had it made clear to me for BMST 2019 that fuel doesn't mean any old combustible. It covers the racier gasolines, methanol, ethanol, nitromethane, nitrous oxide and, presumably, water injection. I had planned to run gas with a shot of nitrous and propane. AMA says you cannot run propane. But you can run hydrogen. Go figure. So be sure to double check the rules for the specific event you plan to attend.
Will the fuels at BMST be the same as the WF?
Different suppliers (ERC for BMST, VP for WF), but similar types of blends.
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I really can't thank you guys enough, this information is invaluable! Not used to folk being so helpful, or maybe just used to water speed records
The main focus is still the P-PC and P-CG records, but good to know I can attempt the AF and AG if I have time and will only require minor changes. Would be good to go after the P-P record too but that's 66mph, will have to see what my speeds are like first
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Engine is now tuned, couple tweaks to the exhaust, rotary disc, and barrel ported and the bikes gone from 9.6rwhp to around 12.5. Still have a couple things to do, need to do a squish test on the head, static compression is at 171psi at the moment. Need to get new chain and sprockets and change jets
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Point of reference is a funny thing - 12.5 rwhp - yup I would be happy to get that little bit extra in my 2,000cc car engine, then you tap the casio keys (other brands are available) and it becomes a 30% increase over what the bike had and its wow, that is brilliant.
Keep up the good work and lets all hope the gods of speed intervene in this virus business and some of us get to experience the joy ( :deal cromag :? :-o :cry:) of trying to import a vehicle next year.
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Pretty decent improvement, did some more jet tuning with the carb, new chain and sprockets on, a couple more bits to do inside the engine which I'll get done over the winter. Should be around 13.5rwhp when I'm finished I hope.
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A five gallon can of Sunoco race fuel was in the crate with the race bike when it was sent from Oregon to the UK. This way, the bike used the same brand and type of gas for dyno testing and the race.
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Didn't know you were allowed to ship fuels/oils?
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I am sure that is what WW planned to say to the customs agent ...."I didn't know you were not allowed to ship race fuels" :?
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Anyone have first hand experience of carb jetting at Bonneville? The online calculator say go down 10 numbers on the main, but others I've spoken to say you may even a need larger main jet to aid cooling
Is it worth using a dyno in Salt Lake City to set the carb up before records week?
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Scott Horner's shop - Heads Up Performance - is in Sandy, a south suburb of SLC. He's a Bville racer, and we've many times had him do a final tune on our bikes before we head out to the salt.
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The largest jet that produces good power is determined on the dyno. Then, a Mikuni slide rule is used to calculate the change in jet size for the local conditions. It is usually no more than one size leaner and maybe two sizes in some cases. This method works for me where the dyno is near sea level.
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Further on retuning for the salt altitude:
Steve Knecum built and tuned the motor for Nancy's ZX14 at his shop near Philadelphia. His dyno showed something like 215 hp. We stopped at Heads Up a few days later and Scott dynoed it and found that we had lost a dozen* or more HP on the cross country trip. Scott gathered up some HP he had lying around the shop and installed 'em in the motor. and Nancy got a record at the event.
*Yes, we considered that the two dynos almost certainly were not matched, that comparing two dynos is more of a "relative" than an "absolute" thing, when we came up with the power loss numbers. My point is to offer my experiences in re-tuning for Bville altitude.
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I have been tuning my 2-stroke at 500' altitude and then taking it to Bonneville with intensions of slowly jetting leaner until I find the best tune.
What I have found with my 500' jetting is that it seems to be a bit rich for the first half mile then as the heat builds it leans out.
The plugs have no deposits and the EGTs are in the 1250f degree range.
I may be chicken and leaving HP on the table but so far no seizures.
Someone once told me the secret to running 2-strokes at Bonneville is to bring plenty of barrels and pistons.
Results may vary, Don
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Interesting, so in reality the jetting changes required are generally not as drastic as the calculator says?
Been playing with the jetting already, got it in the sweet spot, main jet is good just the needle jet to tune. If it's going to be close to the same I may just adjust on the salt
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The underside of the front of the Triumph fairing is shown in the fuzzy photo. It is shaped to be an air scoop and to capture and direct air flow to the front of the cylinder and head. Maybe this idea would work on the little two stroke engine. Some race fuels work better in two stroke race motors than others. Your fuel supplier should know about this and be able to give recommendations.
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The smoke test is attached to the latest post in my build diary. It shows how the scoop shape of the fairing traps air and directs it to the engine.
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That's seriously cool! Not sure I'm allowed any aero changes at all for my classes but I love seeing the effort that goes into the "serious" builds
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Just looking at the FIM records, this appears to be the same as the guy on the same bike as the P-P 100cc record.
(https://iili.io/KzWuu2.md.png) (https://freeimage.host/i/KzWuu2)
Might be achievable for me, can I go for an FIM record at BMST?
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You can run FIM at BMST. Read all the requirements - EKG/stress test required if over 50, FIM approved helmets with the appropriate tag, two hour turn round for record runs are things to be aware of. AMA is a lot simpler to run - simple medical form, Snell/ECE helmets, same day turnaround for record.
If SCTA is on the radar too ( i.e., you decide to live in Utah for a month and attend both BMST and an SCTA event), requirements for leathers are different than AMA/FIM - no perfs or stretch panels allowed except armpits (and maybe backs of knees?). It's harder to find off the rack leathers for SCTA than leathers for AMA/FIM, which can be standard road race type with stretch panels.
So if you want to run in all three organization's events you would need an FIM $approved$ helmet, SCTA approved leathers, and a stress test if over 50. I would maybe put that money into more go fast parts instead and just run AMA. Fingers crossed we have a BMST this year. Otherwise I'll be looking for some SCTA leathers myself.
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SCTA leathers requirement changed in 2017 and are a bit more lenient than in the past.
I would quote but it's more than I'm up for one finger typing. :-P
Don
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Don't have an SCTA rule book handy, but I did google something about an "update to the 2016 SCTA rules for leathers". Presumably that's the 2017 change you mention -
7.C.2 LEATHERS
One-piece or two-piece 350 degrees (zipped together) all leather is required and the zipper must be sewn to the leather. The use of the leather manufacturer's engineered materials, such as stretchable Kevlar, perforations, or any other of the manufacturer's materials, in non-critical areas is permissible. In critical areas (knees, elbows, forearms, back, shoulder, hips, etc.), armor or two layers of leather is highly recommended. Riders of motorcycles in the fuel classes are recommended to wear Nomex underwear or something similar in nature. Suits of synthetic materials are not permissable. Fairings (speed humps) on the back of leathers will be allowed in partially streamlined classes only.
Here's the AMA rules -
2. P. (IV) LEATHERS
Suits made of synthetic material are not permissible. The use
of stretchable Kevlar and perforated materials in non-critical
areas are permissible. Leather suits shall be one-piece design
or joined by a full circumference zipper at the waist.
V16.1 25
Leathers cannot be too big or loose. Critical area (knees,
elbows, forearms, shoulders) armor or 2-layers of leather is
highly recommended. Due to invisible flames, riders? of
motorcycles burning fuels of Methanol content are
recommended to wear Nomex underclothing or something
of similar nature.
So it does appear that the regs are more or less the same these days and an SCTA approved suit does not have to be solid leather everywhere. I stand corrected.
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Doc, you are right on the SCTA 2016 changes but there were a few minor tweaks added in 2017.
Thanks for posting.
Don
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The difference in the 2017 SCTA rules is simply that you can run a speedhump suit in non streamlined classes if it is an airbag suit.
Fairings (speed humps) on the back of leathers will be allowed in partially streamlined classes only, this requirement does not apply to leathers equipped with air bags.
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Thanks for all the info, will bear it in mind if I am competitive at Bonneville. Looking at the FIM records it seems as though I could attempt it at Elvington down in England, which would mean higher speed - not being on salt or at altitude
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Won't be going to Bonneville this year, just too many uncertainties with covid. Might look at doing something in England if they go ahead, and planning a return to Coniston to improve my water speed record
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Been doing a bit of a restoration on the bike, frame and a lot of other bits have been powdercoated. Really pleased with the finish, as new.
New shocks, fork oil, rear mudguard and stainless front mudguard
(https://i.ibb.co/phFKz3p/269921192-241922864685013-5058217669578727375-n.jpg) (https://ibb.co/z6v2RSw)
(https://i.ibb.co/HdN5mQv/269987998-732825604788832-2311280074768399176-n.jpg) (https://ibb.co/YZDHvG9)
Also been doing some fiddling with the engine, need to get it back on a dyno to see if it's helped
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Was playing with some free programs for pipes, I think mine is not too far away from these given the restrictions for class
(https://i.ibb.co/wJ17NxS/Screenshot-2022-01-06-at-16-47-18.png) (https://ibb.co/XyTDZv7)
Drew them up in Rhino quickly
(https://i.ibb.co/bmyJh89/Screenshot-2022-01-06-at-10-59-25.png) (https://ibb.co/tKNXfWr)
Got a new ignition coming all the way from New Zealand, very kindly given to me. Going to get that on then take the bike back to a dyno to play with jetting
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Can you measure and input your stock pipe in these programs to see where Suzuki optimized their exhaust? My guess is that you have to use a pipe that appears stock in your class
:cheers:
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There's no cone inside the standard pipe, currently working on it 8-)
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Anyone able to confirm, does the exhaust have to only appear stock or does it need to sound relatively stock?
I've modified it a touch which has helped performance but it's much louder than before
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Anyone able to confirm, does the exhaust have to only appear stock or does it need to sound relatively stock?
I've modified it a touch which has helped performance but it's much louder than before
Look stock, sound doesn't matter. However, you should be able to stand at the back of the bike looking down into the exhaust and not be able to tell if it has been modified.
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Well sorta.... the exhaust should look stock... the exit from the muffler should appear stock, it cannot be enlarged. But... if you modify and the exit remains stock size you should be good. I reworked the muffler on the GSXR 1000 when we set the Production record... 2003 ish... The can was a little tough to reseal to look like stock...
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When we took Nancy's 1350 P/P bike through Impound we had complied with an inspector's suggestion that he'd like to be able to find some type of baffle or obstruction when he poked a pencil into the exhaust outlet of the factory cannisters. Said cannisters and their innards had received some attention as is allowed, including the faux baffle, but we were questioned about the weld seams of the cans, which could be described charitably as "buggered up". Yes, we did get the record certified, but not without a fun few minutes telling the inspectors that what they were seeing was simply the work of a trainee welder on a Monday morning shift at Kawasaki.
Were they convinced by the story or was it Nancy's blonde hair? :roll:
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Excellent thanks for that, I'll put a factory baffle in the exhaust. Shouldn't hurt the power too much, might stop my ears bleeding so much!
Taking my time with the exterior welds and grinding them back so they look just like the factory ones. Quite pleased with the results so far but will need to get it rechromed or powder coated afterwards, I don't have blonde hair so I'll have to do a better job of it :laugh:
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Also over 200mph on a production xz15 seems like an excellent speed, haven't seen many P class records where the speed is higher than the original listed for the bike
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One more question, the rules state stock carb which I have but I've used liquid metal to smooth the inlet on the carb into a bellmouth. Is that allowed or does it have to be untouched?
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Again appear externally stock... anything they can't see from the outside is legal.
:cheers:
Maybe they have changed but I've not heard that any inspector wanted to see a baffle in an exhaust... I would send that question to the tech chair listed in the rulebook. The rule says the hole is the same diameter and placement in the exhaust. Please report back on what they tell you.
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Sounds promising, could maybe get away with a powerjet too.
Can't find the tech chair in the rulebook, do you know who it is? Or an email address?
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from the 2021 book
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To be clear, is the plan to run SCTA, AMA or FIM?
Or all of them?
Don
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Thanks for that, have sent Russ an email
the plan at the moment is BMST this year for AMA records
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If you are doing AMA you need to send questions to tech@bonnevillespeedtrials.com and/or info@bonnevillespeedtrials.com
The guys I threw out there are all SCTA contacts.
Drew Gatewood (AHG), the AMA and FIM inspector is on here occasionally. His email is gears55@frontier.com
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Ah excellent thanks, emailed them
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Been having a read through some posts on the forum and the rulebook. Not entirely sure if I'll get away with the liquid metal I used on the carb inlet to smooth it off. Anyone know if that's allowed?
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Well you are not changing the venturi size... that is determined at the throttle plate.
This from the AMA rules
1. Production (P)
a. Use the same engines (gasoline only) originally installed
in the specific motorcycle frame at the time of production
and ensure it meets the definition set in the ?P? frame
class (See 3.11D). Original equipment (OEM) shall
include cylinders, cases (crankcases), heads, and
carburation or throttle body (stock venturi size), kickstarter or electric starter. Displacement determines the
class. OEM displacement specifications must remain
stock.
b. GASOLINE ONLY
3. Production, Vintage (PV)
a. Same as 3.11L.1 but with a production date prior to 1956.
b. Allowable overbore in this class is + .050- inches over
OEM standard bore to remain in displacement class.
4. Production, Classic (PC)
a. Same as 3.11L.1 but with a production date prior to 1981.
b. Allowable overbore in this class is + .050- inches over
OEM standard bore to remain in displacement class.
But you could put a .050 bore on the stock size and remain in class... :? Just saying...
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4. Production, Classic (PC)
a. Same as 3.11L.1 but with a production date prior to 1981.
b. Allowable overbore in this class is + .050- inches over
OEM standard bore to remain in displacement class.
But you could put a .050 bore on the stock size and remain in class... :? Just saying...
I have always wondered what that means. For instance, if your original stock class is 1000cc and your stock displacement is 999cc, but the .050" overbore increases the displacement to 1001cc, can you remain in the 1000cc class? For non-classic bikes you would have to go to the 1350cc class.
The wording is confusing.
Don
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Yeh that's what I'm reading too, it is the standard carb with standard venturi size so should be alright. Will try source another to take with me just in case
From what I understand of the displacement rules you can rebore up to .050" but have to remain in the displacement class. So if you've got an 89cc bike running in the 100cc class you can bump it up a bit, same as non classic bikes only you're allowed a larger re bore
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Yeh that's what I'm reading too, it is the standard carb with standard venturi size so should be alright. Will try source another to take with me just in case
From what I understand of the displacement rules you can rebore up to .050" but have to remain in the displacement class. So if you've got an 89cc bike running in the 100cc class you can bump it up a bit, same as non classic bikes only you're allowed a larger re bore
Hopefully your carb work didn't change the venturi size... Mostly they are looking for folks that bored the carb larger than stock... more air, more fuel, more power
Actually in production vintage and classic you can exceed the class limit. But only if you are working from stock bore +.050 cylinder recondition allowance. If your motor was exactly 100cc and the .050 made it 105cc then you are legal. You get the stock bore + the .050 in classic and vintage... no matter where it lands provided you were in class with stock bore and stroke.
Take proof of stock specs...
Now don't take my word on it.... send an inquiry to the BMST and confirm it... before you bore... but that's the way I read it.
Its been years since I raced at the Bub, now BMST, but that's the way it looks.... Maybe the more recent participants will chime in with real life experience
:cheers:
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I've run the same 72 Yamaha in the classic 350 and been measured many timed by Drew and by Curtas. stock bore is 347 + .040 over makes it 358 if I'm calculating
correctly somebody check it, and I've remained in 350 class
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Chis, that's the number I get as well... So your 1mm overbore allows you to race in classic 350 even though you are 358cc. That is pretty much the real life info roflhat needs.
Thanks :cheers:
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Wow interesting, that's good to know. Currently still at the standard 98cc so potentially a bit more to be had there
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Reply from Drew regarding smoothing the carb entry, still not sure if it's allowed or not
"Hello,
As stated in the regulations: A "production motorcycle class" is "as produced by a recognized manufacturer".
The o.e.m. venturi size requirement has a definite mention in the rules.
However, if one was to be protested by another competitor they could run the risk of their component
being deemed NOT "as produced".
Best of luck with your build."
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Well I guess the same could be applied to high compression pistons, big valves and head porting....
:? cromag
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Drew is saying that it's only against the rules if you get caught. If you are the only bike running in a class there probably won't be much protest if the mod is not obvious. But if the scrutineer spots it in impound after you record and determines it's not legal you have a problem. My teammate was put into a state of anxiety in scrutineering last year because the scrutineers were somewhat split on how to measure the maximum height that a seat hump may be above the rider's butt on the seat in Modified. This anxiety was over about 1/8" of height. In the end they determined it was legal. I remember one year when Hiro Koiso had to chop about 1/4" of the end of his rear fairing to be legal overall length.
It pretty much boils down to whether you think you have a chance of setting a record and how much the mods might help. If you need 5 more hp to get a record and smoothing your inlet tract might be illegal but gets you 1 hp it may not be worth the effort if you can't find 4 more hp elsewhere.
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For all the difference the liquid metal makes I may as well just put it back to standard. Want to make sure the bike is legal, a long way to go to find it isn't!
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ROFLHAT - are planning on bringing this bike to BMST this year? I'd like to catch up with you to get some ideas for my upcoming build. Thanks!
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Sorry haven't been on for a while!
No fortunately I cancelled plans to come over this year, 2023 is the target