Countershaft rotation Speed- (chain drive related)

[Rick G]

THe tubing your using is EMT (electrical mechanical Tubing) and its a low carbon steel and as such its not very strong . How do I know?  I was going to make a frame for a dirt bike out of it, until an engineer talked me out of it! YYour not the only one with crazy ideas!

[GAJim]

I was looking on e-bay and saw an 82 seca 400 parts bike for sale this bike looks close to the vision in style and was chain drive.  might be a good donor for parts swingarm looks similar monoshock etc......

[Blake]

ah..low carbon steel.  i know exactly what you mean... yeah..  well..it may not be strong..but for just being an exhaust i dont see why it shouldnt old..  it welded pretty good... and i mean..its not holding any weight...  but yeah..definately not for frame..


but talking about frame..  what pipe would you suggest for a frame? is there some specific grade of steel that is generally used?..or..what about chromoly?..can you weld chromoly to like our frame?




Blake

[Blake]

Just got a reply from a Carl Wadkin from the link you put up Hugh...



Hi Blake,
We are 5 miles from Bath in the South West of the UK.
I was inspired by a road racing team who ran an XZ in a really nice space
frame. They had a new and longer gearbox output shaft made and I guess it
must have had an outrigger bearing too, though I never saw the bike close.
For my part I choose the easier route of making a special sprocket with a
splined hub to replace the bevel gear, I also had to mill away the mountings
for the bevel housing on the crankcase cover. A sealed bearing needs to be
fitted too as the bevel box gets its oil feed through the bearing.
I chopped away most of the frame and built a new section on to take a Yamaha
SRX600 swinging arm and Suzuki GSX600 wheel.
I never tuned the engine, rather concentrated on removing XS (sorry) weight.
I removed the balance shaft at an earlier stage and my wife didn't really
notice much difference in vibration though it did go a little quicker. Her
best was 13.2 on one of the old wartime airfields we used to race on (loads
of wheelspin). I'm sure on the drag strip we could have got in to the mid
12's easily.
Good luck, it's a great little engine with lots of potential.
Kind regards,
Carl







interesting....so looks like he just did what were trying to do.. change out the bevel gear.  but then he does mention having to chop the housing around it.  but hey... at least we have a starting place for a swingarm now (although he did say he chopped the frame to get it to fit.. hmmm...  the problem were going to have is that our swingarm is flat at the pivot area..and also..connects to the frame on the outside.. not like the newer ones of today... hmmm..





Blake...

[rick_nowak]

frame material that would work well would be 1020seamless tubing with appropriate wall thickness- .060-.080.  your local steel service center could help you kind what is commonly available.  some would recommend 4130 chromoly but if the geometry is good and the welding is done correctly it is not needed.  the benefit of chromoly is that it has a higher tensil strength and you can use a thinner tube.  that makes it harder to weld and it is already hard to weld well.  among other things, the heated steel needs to be re-heat treated for best strength.
the quick and dirty method would be to chop up some other nipponese frame with same tubing size.  pretty cheap