Landracing Forum
Bonneville Salt Flats Discussion => Build Diaries => Topic started by: Bruin on July 11, 2009, 12:51:35 AM
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Speed Team Doo ran '70 and '71 Triumph 250s in 2008 and I shared one of the bikes with my wife. When it comes to racing, mine is better than ours, so I snatched an '82 Honda XR 500 off Craigs list. We knew it was not bred to the track (That didn't stop us from tweaking the Triumphs) but as old thumpers go, it's four valves and dual headers made it a fierce torque monster in it's day. Perhaps we could harness a little of that umph. To paraphrase Burt, "Anyone can buy a fast bike, the trick is to make a slow bike go fast."
This is the before picture.
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We quickly rolled it into Ed's Heat and Hammer Emporium where he cut the butt end off and proceded to turn a tall in the saddle dirt bike into a long and low down Bonneville racer. With limits on power we knew it had to be slippery, a laydown bike seemed the way to go.
The frame turned out quite nice, untill I tried to spray bomb it on a hot day. I could have gotten more lasting color with chalk.
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Our team's forte is to do the best with what we have. To lower the front end we rammed the tubes up through the triple tree and stiffened the mushy MX forks by cutting the springs down and plugging them with PVC. We have plans to use the towering tubes as fairing support structures. To get the rider low meant moving the gas tank to the rear so he/I could lay on the backbone and look crosseyed between the steering neck.
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Keeping true to the STD motto, we made doo as much as possible by building as much as we could by hand. Ed created the apple wedge gas tank to fit the curve of me bum. It is tapered wide at the top and narrow at the bottom hoping fluidics would keep flow pressure maximized. (Hey, it sounds like a good theory.) :cheers:
(That is the beta tank, Ed went back made another because the enemy of good is better.) :evil:
The lay down seat pan was made to keep my torso horizontal and minimize my wind profile.
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The idea of taming wheel turbulance and streamlining the fork tubes seem to have merit so Ed slapped ears onto an old fender. It is welded onto halfpipe sections clamped to the legs, made for a very secure mount.
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Here is the front of the frame where you can see how we kept the engine cradle and neck. I don't know if you can call us "green" but note how we recycled the motocross bars into drag bars. Laying on the backbone gives me an interesting view.
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With a chain nearly double the average length we made a guard that sandwiched it between adjustable sliders. Safe and whipfree.
Lowering the towering dirt bike made the Kicklever bounce off the ground in mid crank. We also remembered what a pain in the arse it was to have a pit monkey follow you around with a jackstand every time you hit the porta potty. So Ed came up with the idea of a mechanical center stand that can crank the bike sky high and is as stable as the Dollar.... er, Yen.... maybe Euro... as stable as the Yaun. Handy for stopping, kicking and field maintenance.
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Note the second gas tank Ed made, much more purty. The homemade rear fender may not be too curvy but it is hidden by the rear fairing. It was made out of sheet aluminum rolled to the micrometered diameter of my butt. Keep an eye on the two open fork tube/fender/fairing mounts, we have plans for them.
It all came together nicely, the holes? Stay tuned.
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Hi Bruin, Nice pics and nice bike. How long is it?
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Thanks, About 106" stem to stern. Credit Ed for concept, creative solutions and solid skills. And he wants you to know, his is longer.
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We did recycle our first rear fairing attempt into an engine shield. A bit bulky, we aren't "in" love with it.
When laying down you need a pillow, or at least a chin rest... and a damper.
The straight pipe needed a little bling on the end, something adjustable to break up the heart quickening thumpa-thumpa.
Nitro? That is sooo overdone. We are talking Propane baby!
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The biggest project of the build was the front fairing. Here we were venturing into uncharted waters and made it up as we went along. The first step I assumed the position while Ed outlined my shape front and side. Then he built a model like you would a ship, peg board ribs then thin plastic planks for the compound curves.
Then a plug was formed over the model by friend of STD, Jimmy-John. Much easier said than done.
But the shape was perfect, it shields my head, shoulders and elbows.
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Jimmy then gel coated the fairing plug and a split mold was fabricated.
Mold done it was time for glass, here Ed gives the bottom half a trim.
The fairing was cast oversized so we could trim it back, but you can see the design we were after.
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Then we trim the fairing to shape, making sure the rider is visible and only the hands are inside.
You can see the shape of my helmet, shoulders and elbows in the outline. You may also notice it needs a windshield. Thats next.
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Store bought windshields seem so impersonal so we rounded up some polycarbinate and using just the right recipie cooked it up in the kitchen stove. Time and temp are crucial so do your homework. Our best result came when we slapped the softened material in between the fairing mold and blank. That polycarb is tough stuff. We tried to break a failed expeirmental sheet by jumping up and down on it and could not!
Here you see it mounted and protected from scratches with masking tape.
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Things were starting to come together. Looking more like a salt lick all the time.
Since gas has to flow rear to front we insured a nice supply with an engine pulse powered fuel pump.
Remember those frame tube holes in the back of the bike? Perfect for a detachable push bar. It keeps the heathen from getting peanutbutter and jelly on the paint, perfect for loading, unloading and my girlfriends arobics.
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Finally, assembled on the Fourth of July, it is done... more or less save the locktite orgy and engine maintenance. About nine months of weekends, untold overtime by Ed, help from Jimmy-John, chow from Deb, patience from Tucker, countless miles commuted and hours of bench-racing brotherhood. Team STD produced my 2009 BUB Land Speed Racer.
The test ride proved hopeful and we can't wait for the dyno.
The name? A hard riding gal pal of ours stopped by to look at it today. After checking out last year's green bike and this one she asked, "What are you going to call the big red one?" Of course I had to answer, "Big Red One". It fits STD perfectly, if you are going to ride one, ride a big red one!
(With a salute to our local 1st Army, The Big Red One here in KS.)
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Cool project! The Honda has lots of character, thanks for sharing the build process.
Most importantly, it sounds like you and your friends are having fun.
Good luck at Bub.
Scott
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looks like fun was had by all, and that is truly what counts! Solid build, and good luck at BUB!
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Well, Brian hit the high points, so I'll throw up some more detailed stuff, just in case anyone has any interest at all in our project.
This is how we arrived at the profile. In one of the earlier pictures you can see Brian laid out on the frame. Here you can see the cardboard profile where we traced his outline. At this point we were using very precise SWAG methodology to determine the optimum aerodynamic shape :-D. We had committed to the rear but were still sketching on the front.
(http://i101.photobucket.com/albums/m68/Whizzbang02/XR500%20salt%20racer/100_3982.jpg)
Developing the shape of the front fairing. This is the first (very rough) draft mock up using cardboard and poster board to help visualize the shape. You can see the rig I made up to transfer the profiles at different heights to heavy plastic sheet in order to create the station formers for the plug.
(http://i101.photobucket.com/albums/m68/Whizzbang02/XR500%20salt%20racer/100_3979.jpg)
Profiles cut out, ready to be transferred to heavier material.
(http://i101.photobucket.com/albums/m68/Whizzbang02/XR500%20salt%20racer/100_3981.jpg)
Formers made and "egg crated" together, with thin Lexan strips laid on to establish the surface contours. Think cedar strip canoe construction. This seemed to be the easiest and quickest way to get the smooth compound contours that we were after. I know a lot of folks use foam billets and carve the shape. I've tried it in the past and always have a really hard time getting 2 sides that are even close to the same shape. Besides, I hate the mess that sculpting foam makes. :x
(http://i101.photobucket.com/albums/m68/Whizzbang02/XR500%20salt%20racer/100_4050.jpg)
Brian pretty much covered the rest of the fairing earlier, so we'll let the fairing tech die now.
Another issue in LSR is gearing selection, and being able to change final drive ratios if needed. The XR500 is a typical dirt bike, with a large rear sprocket stock. We looked at getting another rear wheel, but in keeping with the STD philosophy we decided to make doo with what we had. This meant that we needed to get a selection of sprockets to fit the rear wheel. The smallest sprockets available for this particular wheel weren't any where near what we feel we need, and since there was already a good assortment of sprockets on hand for the red 250 Triumph we run we decided to get double duty out of them. This meant that we needed to modify the hub so that the sprockets would go onto it, and modify all the sprockets with extra bolt holes to fit the holes in the hub. No problem, we have the technology. :-)
(http://i101.photobucket.com/albums/m68/Whizzbang02/XR500%20salt%20racer/100_3963.jpg)
(http://i101.photobucket.com/albums/m68/Whizzbang02/XR500%20salt%20racer/100_3961.jpg)
(http://i101.photobucket.com/albums/m68/Whizzbang02/XR500%20salt%20racer/100_3966.jpg)
In case anyone is wondering, the actual bearing is still inside the ribbed portion of the hub. The part that I cut away for the other sprockets is only holding a preload nut and seal, so no real change was made to the structural integrity of the hub. I looked long and hard before doing that little mod :-D .
(http://i101.photobucket.com/albums/m68/Whizzbang02/XR500%20salt%20racer/100_3968.jpg)
(http://i101.photobucket.com/albums/m68/Whizzbang02/XR500%20salt%20racer/100_3967.jpg)
Decided to make the fuel tank from aluminum, just because we can. I used .040 3003 for the first one, and was real unhappy with it for a couple of reasons. First, it warped a lot from welding and looked like s**t, and second, I felt that it may be too thin to withstand vibration, resulting in cracks forming. The safety consideration sealed the deal, so I made another from .080. It looks much better and I'm happy with the strength of it now. It's also mounted on rubber isolators to help deal with the thumper vibes.
(http://i101.photobucket.com/albums/m68/Whizzbang02/XR500%20salt%20racer/100_4071.jpg)
Just a close up of the weld, since I really like nice welds. :-D
(http://i101.photobucket.com/albums/m68/Whizzbang02/XR500%20salt%20racer/100_4077.jpg)
Decided we needed a substantial inner fender on the rear due to the location of the fuel tank. If something were to happen to the tire we don't want anything hitting the tank. Built from 16Ga steel. Wrapped it as close to the sprocket as we could on the left side to try to keep the salt spray away from the chain. Don't worry, in the final trim it is above the rim aft of the axle. :lol:
(http://i101.photobucket.com/albums/m68/Whizzbang02/XR500%20salt%20racer/100_4068.jpg)
Tail fairing time. We spent a lot of time looking at other machines as far as streamlining goes. One thing that we noticed is that there are quite a few machines that have a lower fairing that flows from the front all the way to the axle (and beyond in a couple of cases that we saw :roll:) with cutouts for the riders legs that fit very closely and have relatively sharp edges to help air flow. While this is obviously the best possible solution within the rules to streamlining this area, we decided against doing it. The reason for that decision is safety. It just looks like there is a real probability of getting a leg hung up in the fairing in the event of a get off, which would make a bad situation a whole lot worse in our opinions. What we went with is a taper on the lower part of the fairing almost all the way to the frame, making it very hard to get hung on the bike. You can clearly see it in this pic.
(http://i101.photobucket.com/albums/m68/Whizzbang02/XR500%20salt%20racer/100_4069.jpg)
Brain came up with a swap meet special Lectron carb that he wanted to try, so an adapter had to be made to get it to fit onto the engine. He's still not sure he's going to run it, but it does seem to work fairly well in the limited test running we've been able to do so far.
(http://i101.photobucket.com/albums/m68/Whizzbang02/XR500%20salt%20racer/100_3960.jpg)
(http://i101.photobucket.com/albums/m68/Whizzbang02/XR500%20salt%20racer/100_3958.jpg)
I'll end this massive post with a couple of pics of the first roll test down the street last fall. Not under power, this was just a test to make sure that Brain would be able to make the transition from stationary to moving and find the pegs and controls without trouble. Seemed like a good idea, since it would have been "not good" to finish the bike and discover it to be unridable. :wink:
(http://i101.photobucket.com/albums/m68/Whizzbang02/XR500%20salt%20racer/100_3989.jpg)
(http://i101.photobucket.com/albums/m68/Whizzbang02/XR500%20salt%20racer/100B4041.jpg)
CHEERS ALL, and we'll see ya on the salt. :cheers:
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The Triumphs were featured in an interesting article in a chopper magazine a year or more ago. This got me interested in the bikes and it was fun to watch them race last year. It is nice to see a build diary. Some of the ideas will be used on my Triumph.
A simple question. Why are so many folks in Kansas interested in land speed?
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The Triumphs were featured in an interesting article in a chopper magazine a year or more ago. This got me interested in the bikes and it was fun to watch them race last year. It is nice to see a build diary. Some of the ideas will be used on my Triumph.
A simple question. Why are so many folks in Kansas interested in land speed?
Oh no ya don't! Don't try to blame this affliction on us. It's not our fault you took the free taste. :-D
That would be "The Horse Backstreet Choppers". The editor was nice enough to run a full year (10 issues) series on last years effort, which by the way was the first time any of us ever went to the salt. We took the taste, and now have the fever bad. :lol:
So I looked at your build diary and don't see any mention of engine size, just Triumph. Are you bringing some competition for us? :evil: :cheers:
Looking forward to seeing ya on the salt. Now that the XR is in Brian's capable hands for tweek and tune and the loktite orgy I'm putting the engine back together for the Long Red One that I ran last year, hopefully it'll hold together this year long enough to put together a couple of respectable runs. Last year I had a carb problem resulting in a massive lean condition (it was self inflicted :-( ), and ended up seizing the engine several times, had to rebuild the top end twice in the pits. Still had more fun than the law allows, but it seriously cut into our pit cruising and socializing/meeting folks time.
Oh yeah, I can't answer for those Kansas people, I'm actually in Missouri, and from Ohio originally, but I have a theory. I think maybe it has something to do with all that flat land they have there. :roll:
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Finished off painting the sheet metal, note my fellow Bonneville rider/bride/model, the fender and engine cowling. Still need to get some sponsor names and the correct class designation on it. It turns out my swap meet Lectron Carb is a vintage 70s model and in need of a slide/needle upgrade from the gents at Fast by Gast so it is in NY right now. E. V. Engineering says the crank case pressure pump won't work properly on a four stroke so I need to rig an electric pump. I found a low psi pump that only draws 2 amps so I plan to run it off the tail light hot wire. Slapped in some valve seals so maybe it will cut back on it's smoking.
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The triumph is a 790 cc twin or a 395 cc single, depending on its mood and whether or not I figure out the carburetion problem. I'm looking forward to seeing the bikes at BUB.
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Fast By Gast told me my swap meet Lectron is a 70s era model and needed a needle/slide upgrade to make it Bonneville worthy. Took almost a week to get it back from NY but I dropped the new metering rod in today and the big 500 cranked right up and ran around the block with nary a stutter. I dare say it's near Dyno Time. :cheers:
The mellow rumble of a 500 thumper on a straight pipe is sweet... if you can call serial cannon reports mellow.
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The pulse fuel pump didn't work on the engine breather pulses so I find myself tinkering around as I wait for the six volt fuel pump to arrive. The built in auto-kickstart-compression release feature wasn't working so I routed its' cable to an old Amal choke lever that bolted handily to the frame. It works great as a manual compression release. I also ground the air valves off the top of the forks. I think the cut down springs will suffice plenty for Bonnie and those sharp valves were just waiting to poke me in the eye.
I tweaked up a little engine case breather for my wife's Triumph. I accessed the tach portal by filling the hollow cap with alloy rod, drilling and tapping it, threading a piece of thin 1/2 inch pipe and screwing it all together with a little JB Weld.