Landracing Forum
Bonneville Salt Flats Discussion => Build Diaries => Topic started by: mgriffiths on February 11, 2021, 01:44:42 PM
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Hello,
I thought I'd post my progress on RailGun, my 500cc SC-G (sidecar) challenger.
I had no intention of building this bike, but I kept having so many ideas I just had to make it happen. I wanted to make this bike as low and as thin as possible keeping the frontal area to a minimum, and also to keep it as light as possible.
The key design aspects -
* Using the Kawasaki EX-500 engine (again), it's an over-square, DOHC 4-valve with a 6 speed gearbox. It produces decent power and great reliability. There are more powerful 500cc engine options, namely going 2-stroke (eg. RG500), or de-stroking a modern 600cc, but to keep things economical, I decided to see how far I could push the EX500.
* Design a novel low and rigid front end. I looked at a number of options but ended up designing a front end that was going to keep the frontal area to a minimum, but also provided excellent rigidity. It's basically built from hydraulic tubes, off the shelf shocks/springs, and CNC-milled triple tree clamps.
* Central chain drive. Most motorcycles have a chain running from the engine to the rear wheel directly, but this is very inconvenient for the riders legs/feet since they have to be "outside" of the chain putting them out in the air stream. With this design ,the chain runs right down the center of the bike allowing my legs and feet to be completely tucked in.
* Aluminum construction. While steel construction was possible, I felt I could build it in aluminum to save a lot of weight. Weight is not the biggest factor to high speed, but rolling resistance is not trivial and in fact can be significant on salty surfaces. Also, Bonneville is basically just a long drag race, so getting up to terminal velocity before/at the speed trap is critical. Some will know that welding aluminum generally adds "weakness" since it de-tempers the aluminum, so the solution is to over-engineer the frame, and every joint with extra gussets.
* Fuel Injection. There never was a fuel injected EX500, and there are few aftermarket options, so I thought I could build a system myself. With greater flow capability and much better fuel atomization and timing, I feel a 15% gain in power is possible. This system is driven from a $15 Arduino microprocessor and so far I have the bike running fairly well.
* Fiberglass body construction. Having a decent experience with fiberglass building my first bike, I'll be going down this road again, but not for a few more months.
I have plenty of construction pictures, but here is where it started, with a wooden prototype to determine all the key dimension points
Cheers, Mike
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Showing the novel front end
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Showing the central "beam" drive
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Showing the whole bike (it's very very long)
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Showing the Fuel Injection throttle bodies, fuel rail and regulator
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Cool Project... it is a drag race... but the "trap" is a mile long... hard to know if you will need weight for traction till you run. Can't wait to see the body... and see the bike on the salt.
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That looks awesome! I like your idea on the chain drive. The frame looks heavy duty and very sturdy. Also looks like it would be easy to change to larger engines. It's going to need a lot of fiberglass!
Keep sending updates.
Don
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One more pic in the daylight, but from before the EFI installation.
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15% above OEM is about as much as you can get out of a EX500. From my workings with them, as you start gaining above 70 wHP the block weakness shows up.
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I thought I'd post my progress on RailGun, my 500cc SC-G (sidecar) challenger.
Very cool!
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Awesome! More local folks! 8-)
Which event are you going to run?
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15% above OEM is about as much as you can get out of a EX500. From my workings with them, as you start gaining above 70 wHP the block weakness shows up.
Thanks RansomT, if you have any tips for me to keep this engine together I'd love to hear them. I have internally braced the cylinders and have removed the magnets from the flywheel to try to push out the grenade event :)
BTW the best advice I ever received about the EX was from a Bonneville guy back at the Mojave Mile event -
Cheers, Mike
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Awesome! More local folks! 8-)
Which event are you going to run?
I always aim for Speedweek, and if timing allows this year I'll shoot for ElMo in the early summer/spring.
Cheers from Boulder :)
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Ditch the radiator, way to much drag, replace with a 2-3 gallon water tank and you will have plenty of coolant for a 3 mile run. It looks like you have 3 different chain drives, lots of hp loose in each chain. Typical chain drive efficiency is about 91 to 95% so at the best you would have a drive line efficiency of about 86%. You might consider using a good cog belt for the first two , engine to center line drive and then one for the center line drive with a chain for the final drive to give you easy ratio changes. Cog belts are 98%+ efficient so that would give you a drive line efficiency of around 92%. All belt drive would be 94%. Belt drives have their own challenges not just a straight switch from chain to belt.
On your front forks make the slider longer, greatly reduces the load on the bearings. If you are using plastic or bronze bearings be sure to use something like turkite which is a bronze impregnated teflon, very low friction and low "stickson". Or are you using a linear ball bearing arrangement? If so very good thinking.
Neat project, good to see some "out of the box" thinking.
Rex
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Ditch the radiator, way to much drag, replace with a 2-3 gallon water tank and you will have plenty of coolant for a 3 mile run. It looks like you have 3 different chain drives, lots of hp loose in each chain. Typical chain drive efficiency is about 91 to 95% so at the best you would have a drive line efficiency of about 86%. You might consider using a good cog belt for the first two , engine to center line drive and then one for the center line drive with a chain for the final drive to give you easy ratio changes. Cog belts are 98%+ efficient so that would give you a drive line efficiency of around 92%. All belt drive would be 94%. Belt drives have their own challenges not just a straight switch from chain to belt.
On your front forks make the slider longer, greatly reduces the load on the bearings. If you are using plastic or bronze bearings be sure to use something like turkite which is a bronze impregnated teflon, very low friction and low "stickson". Or are you using a linear ball bearing arrangement? If so very good thinking.
Neat project, good to see some "out of the box" thinking.
Rex
Thanks for the thoughts and ideas Rex, I really appreciate your feedback!
I did think about going with the water tank instead of the radiator, but I think I'll consider this at the end of the process to get the last final couple of MPH out of the bike. I get the aero drag advantage but it seems logistically burdensome- You start a run with 3 gallons of cold water, but at the end of the run you now have 3 gallons of hot water, and what do you do? You can't run again until you wait for it to cool, or go back to the pits and replace it all? Anyway, to start with, I like the idea of not having to worry about it, and I can minimize the drag using NACA ducts to feed the radiator.
Thanks for the education of chains versus belt drive, and I have to admit that I wasn't aware of the efficiency numbers that you've provided. Based on your calculations the chains are 6% less efficient in total, which is very significant, so I'll take a close look at belt/cog in the future!
I am using bronze bearings in the fork sliders, which I think will be okay for what I need, but we'll see. I feel I still have to "prove" the entire design at speed at Bonneville before I make refinements like the linear bearings.
Thanks again, :cheers:
Mike
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An update on "Project RailGun" - SC-500G Sidecar
I've been working on my home brew "EFI system" and have some challenges with basic control of the system, until I realized electrical spikes were reaching up to the logic levels and causing havoc with the injector pulses, looking like a "drunken sailors at a dance hall".
But I accidently found the problem, and have now fixed it, and now have a rock steady pulse train, and now I feel I have good control of the injectors-
Otherwise, I've been cleaning up loose ends on the bike as shown by the blue tape on the rear brake line. I'm happy with the electrical, electronics, fuel delivery, software, cabling, brake, drive units, and cooling systems so I've started to do the finishing work on these.
Here's RailGun at the moment -
How many weeks till SpeedWeek :)
Cheers, Mike
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That radiator out front there is going to hurt aero with frontal size & air flow, can you use sled style coolers & expose them in the body skin or in the air flow under the bike out of the front tire slipstream? How about the sidecar floor, could they go in there?
Sid.
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That radiator out front there is going to hurt aero with frontal size & air flow, can you use sled style coolers & expose them in the body skin or in the air flow under the bike out of the front tire slipstream? How about the sidecar floor, could they go in there?
Sid.
Hello Sid!
I'm going to feed the radiator from the sides using NACA type ducts. It's not perfect, but at least but at least it's not full frontal drag.
Cheers, Mike
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After the first successful run with the new EFI..
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WHAT A PIECE CONGRATS ALL AROUND STEVE
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WHAT A PIECE CONGRATS ALL AROUND STEVE
Thanks Steve!
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Hello Everyone,
I've been working on the Fuel/air maps for RailGun, and after several attempts I've "arrived" at a decent map. The bike runs and behaves well on rides around the block, so I'm optimistic that I'm close enough to be able to do the final tuning at a Dyno in the next few weeks.
I built the simplest EFI I could using parts from a Ninja 650, custom Throttle bodies, and an Arduino based controller. The system picks up timing signals from the coils instead of a timing wheel (since there isn't one :) I time the injector to the opening of the intake valve, which I believe is a good starting point -
Here's the latest video of the bike starting up -
https://www.youtube.com/watch?v=HhY9KJlkDLo
Shoot any questions over,
Cheers, Mike
2718 SCG-500
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Mike, that looks great and sounds great! It is a very clean and compact engine package. When you get back from the dyna let us know the results.
Don
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Nice! designing your own EFI.
The KTM map just may your ticket. Kawasaki in those years that the EX500 were first designed, IMHO, were very zealous on their timing maps and the bikes would loose power when they got some heat in them.
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I've started to build the "buck" for the body so I thought I share the progress so far. With the "pine structure" in place I've bent most of the rods that define the primary shape. There are a few more rods to add, but this is 90% complete at this point. I'll spot weld everything together as a next step, then I'll start the next phase - the metal mesh/striping that I'll wire/attach to the rod structure.
Cheers, Mike
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Another pic
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Completed the steel mesh layer..
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That is a novel way (at least to me) of building the buck for the body. I have built my bodies using foam and cut/sanded to shape. Are you going to plaster this and then lay fiberglass over it? What is the advantage of using the metal rods and mesh instead of foam? I have a body yet to be made on my new bike so want to know if this is a better way. Thanks!
Don
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That is a novel way (at least to me) of building the buck for the body. I have built my bodies using foam and cut/sanded to shape. Are you going to plaster this and then lay fiberglass over it? What is the advantage of using the metal rods and mesh instead of foam? I have a body yet to be made on my new bike so want to know if this is a better way. Thanks!
Don
Hi Don,
The primary advantage is that you can build it "around" your bike, making sure you have all your clearances, and you can make your primary lines very easily. Secondly, there is no waste from cutting blocks of foam. It's still a lot of work, and you need to have good rod "bending" and brazing skills but for me this is the way to go.
I will glass the mesh, then fill (plaster) and smooth to make this the separation layer. A Gel coat, then 2 or 3 more layers of fiberglass then smoothing will make my final body without the need for an extra buck.
Cheers, Mike
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An update on the body work..
After 2 layers of fiberglass, I've "boxed" up the buck so I can staple polyester cloth to the body
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The plywood installed.
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The polyester cloth stretched over the buck
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After applying the resin.
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I'll do another layer of cloth, then maybe fiberglass if needed.
Cheers, Mike
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A couple more pics of the body work progress. Here is the rear cover birdcage and mesh, ready for some fiberglass and gelcoat-
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And with the front (ready for smoothing and hole cutting)
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Getting closer - The front and rear body shells are almost finished, but are ready to be properly mounted to the bike - Then I can start cutting out holes for cooling, exhaust, handle bars, etc.
Cheers, Mike
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Are we running at Speedweek, I thought I heard Slim mention you on his broadcast?
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He is, I heard one pass around 110-120mph :cheers:
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We had to abort a few runs due to new bike problems (Shifter interference, throttle coupler), but I was able to get 2 clean runs before we had to leave. Unfortunately for one pass I ran too low a gear and the other pass I ran too high a gear, so I never reached max speed for the bike. I topped out at 123 MPH (against the 125 record). Very long lines on courses 1 and 2.
Cheers, Mike
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Start Line, Speed Week 2021
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:-D Have a good time, wish I was there!!!
(My 1st time on the Salt Flats was exactly 10 years ago...)
Patrick