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Author Topic: Help the new guy build a LSR Honda CB550f!  (Read 4776 times)
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Old Scrambler
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« Reply #15 on: May 14, 2011, 06:22:26 PM »

I'm an old rookie looking to have a build ready for this year..............Several 550 builders on the sohc4.ent site should provide more info on getting peak torque out of that motor. If you are running in the modified 650 class........do all you can to get your head down low and your hands, knees, and feet tucked in. Deck, shave, high-compression pistons and all will help but don't go too high on the piston profile..........keep the flow. Think about the air intake to get stable air versus a possible drag or vacuum at speed..........its a wide motor but think narrow.
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2011 AMA Record - 250cc M-PG TRIUMPH Tiger Cub - 82.5 mph
2013 AMA Record - 250cc MPS-PG TRIUMPH Tiger Cub - 88.7 mph
2016 AMA Record - 750cc M-CG HONDA CB750 sohc - 130.7 mph
2016 AMA Record - 750cc MPS-CG HONDA CB750 sohc - 137.7 mph
Chasis Builder / Tuner: Dave Murre
Dr Goggles
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« Reply #16 on: May 14, 2011, 06:39:39 PM »

Welcome Trev/Kid/Axel,
you've got just the make-up for this place.Self taught with determination and tunnel vision are perfect attributes for landspeed. There's no shortage of people running basically stock period correct stuff because they want to see how fast they can make it go. The high end of this sport is a little expensive for most of us to get involved in.

Plenty of experience and advice here, plenty of light hearted ribbing too.

 There aren't many people who haven't been told "you're wasting your time with that............, you should just buy a............, ha ha why are you racing that?"

There's nothing surer than you'll find like-minded knuckleheads in this sport and if you love the salt you're a goner. wink
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Few understand what I'm trying to do but they vastly outnumber those who understand why...................

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Peter Jack
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« Reply #17 on: May 14, 2011, 07:17:57 PM »

For Bonneville you shouldn't have to worry about the weight, in fact weight is often your friend. This is unlike any other form of racing and if you've participated with any other form of racing first the weight issue can screw with your mind. Lots of guys carry a fair bit of extra weight on the swing arm. Everywhere else they worry especially about unsprung weight. Go for it, be safe and have fun.

Pete
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Milwaukee Midget
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« Reply #18 on: May 14, 2011, 07:28:25 PM »

Remember - you're at 4400 feet, and I assume normally aspirated.  The head will need to breath well.  Don't let the mixture go lean on the high end. 

It's hot and dry out there - except when it's cold and wet. grin

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« Reply #19 on: May 14, 2011, 08:16:12 PM »

Get a rule book, look at your classes and the safety items. Maybe you will or will not be competitive in your class, but you can be safe, have a lot of fun and learn a thing or two.

Enjoy the ride
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wobblywalrus
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« Reply #20 on: May 15, 2011, 11:29:09 PM »

Trevor, sometimes it helps to find a person who runs an engine like yours in a higher state of tune, such as blown, fuel, turbo, etc.  They can tell you how to set up your motor for reliability.  That is what I did.  I built the lower end to work reliably with lots of power first.  The adding power part is happening later when I get the money.     
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oz
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« Reply #21 on: May 16, 2011, 05:50:04 AM »

Hi Trev
You go for it buddy I am using a 20 year old CBR Motor in my project it aint as old as yours I know but old hat by any stretch of the imagination.
As the project progresses there is less and less of the original motor left things get modified or replaced with more up to date equipment and little by little it gets stronger,faster,better......hmmm sounds like the beginning of the six million dollar man and sometimes I reckon thats what it costs me.
Regardless, to get to Bonneville on something you have built yourself is no small acheivment whatever you build its the journey and the experiances you have that count!

Good Luck Oz
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Stainless1
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« Reply #22 on: May 16, 2011, 07:36:35 AM »

Weight good airflow and compression are necessary when racing on the salt.  It will be a 3 mile drag race.  You said you were shooting for the Bub, so the rules are online.  You might want to consider Run Whatcha Brung... for your first outing on the salt.  It will give you a taste of salt racing while not costing you a fortune.  You run for 2 miles on that one IIRC.  You could ride to the event, race and ride home. 
One of the fast cars one the salt ran an old 500 four Honda motor...  Lingua Bros. & Father M. Lingua 08/91 223.071, but I know Mark went over 250 several times so don't get discouraged. 
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Stainless
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MSA Bockscar Lakester #1000 my fastest mile 245 and change, 84 ci turbobusa motor... but Corey's 233 MPH H/BFL record is still 3MPH faster than mine.
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« Reply #23 on: May 16, 2011, 12:01:20 PM »

I'm going to second what Stainless said on weight, good airflow, and compression being your friend.  Also, the BUB run what ya brung class would be a great intro for you. 

Focus on making the machine reliable and getting your whole entire setup together.  Entire setup = everything from the ice chest, trailer, to the racing tires and tools.  So much of Bonneville is just making it to the starting line - there are a million things to do before you get there.  Definitely get a rule book, figure out your tow vehicle (at BUB you don't need one), where you're going to stay, how you're getting there etc.

There is a wealth of info out on the net on the CB series bikes (I love those bikes).  If you can find any way to increase the displacement towards the class limit, that would help you out the most.  Weight is good, especially over the rear tire and hidden from the wind within the confines of the chassis. 

Have someone take pictures of you in a race tuck on the bike from all sides in that badass room/shop of yours (I love that!).  Then look at what sticks out.  Walk around and see what doesn't look aero and what you can improve and do those things.  Then do it again...and again....and again...
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Shane
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« Reply #24 on: May 16, 2011, 12:05:15 PM »

and say goodbye to the nice finish on any metal parts.  The Salt will lay it's claim to your treasured cycle.  Get some SaltAway and use it but the bottom line is, that bike will never be the same.
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Shane
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kerncountykid
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« Reply #25 on: May 16, 2011, 11:42:13 PM »

Thanks for the encouragement everyone, lots of good advice, I read every bit of it. Further reading on unsprung weight was especially interesting. I'm chipping away at it every day and will post back as I move forward. Getting an outline for the motor currently so I have something to talk about with the machinist.

Also good advice considering the surrounding arrangements like trailer and sleeping. I slept in an alfalfa field and behind a row of bushes last time I rode through Utah on my 550  shocked
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« Reply #26 on: May 17, 2011, 12:42:20 AM »

Hi KCK,   Welcome.   Don't mind the naysayers.   Go with what you have.  If Burt Munro had listened to the naysayers we'd never have heard of him.  This is still an amateur sport but there are those who have taken the fun out of it.  No record, no fun.  I'm running a mid 80s (don't know for certain and could care less) Weslake.  Its outdated but its fun (not to mention four records). 

Just two things.  Weight.  At Bonneville its basically irrelevant.

                        Drag.     Its everything when you run a small displacement engine.

Hope you make it to Bonneville this year.  And the best of luck with the build.
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« Reply #27 on: May 17, 2011, 01:25:58 AM »

Have fun building it, the road to to get their is just as fun. Tony
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« Reply #28 on: May 18, 2011, 12:45:36 AM »

Being of a certain age (I was at the American Honda Convention when the CB500-4 was introduced to the dealers), I've played with some of that era stuff.  One of the things we learned about the old 2-valve engines (keeping in mind that the CB500 was essentially 4 SL125s, sort-of), was valve float as the exhaust side of the head heated up.  This showed up when I was running a stroked and bored SL100 in the 125 class on 1/2 mile ovals (I was young and skinny, and....yes....we just rode around wide-open throttle, kind of like Bonneville!). 

Anyway, the solution was to dish and polish the exhaust valves (lightening and improving gas flow to reduce the heat in that area).  That was a "no cost" project, involving chucking them up in a drill press and using a Dremel tool to slowly dish the valve while it was spinning.  Without that step, the exhaust valve would tap the piston before the end of a 16 lap main.  At that time we had no options for valve springs...and no money to spend on such stuff.  Note that the valve contact condition never happened in a "heat" or an 8 lap "semi".

For cams, we simply had the base circle ground down about .040" and surface hardened.  Nothing fancy....just our best guess, which worked out OK.  Now you can probably get a WEBCAM cheaper than doing your own.

We often ran Mikuni 28mm carbs, with the slide cutaway hand ground to lean out the part throttle enough to "get by".  28s were easy to come by, as the Yamaha guys were putting on GYT kits and throwing the original carbs away.  We also ran the original points ignition with the spark  advance welded full up, to prevent the rattling and bouncing at very high RPM.  Ditch the flywheel and run constant loss battery.

We had good luck with Powerolls exhaust tuning (which was pretty similar to the pipes you see on old CR77 kitted Super Hawks.)  I've made my own megs by gore cutting thin wall tubing, then using lots of hose clamps to close the taper before spot welding between the clamps.  You'll find good length info on the internet.

Maybe some pretty cheap fun!
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Dr Goggles
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« Reply #29 on: May 18, 2011, 01:54:52 AM »

Pretty much nailed it there for you KCK.

What a great board this is....
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Few understand what I'm trying to do but they vastly outnumber those who understand why...................

http://thespiritofsunshine.blogspot.com/

Current Australian E/GL record holder at 215.041mph

THE LUCKIEST MAN IN SLOW BUSINESS.
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