1970 Rupp jackshaft/gear ratios

Finally got the 1970 Rupp Scrambler out of the basement for a maiden test run. It has a H35 on it. (Non Stock Wheels etc) Running 41 chain. Ratios go: 10 tooth clutch to 14 tooth jackshaft in, 12 jackshaft out to 52 tooth rear sprocket. Despite the engine not running smoothly (I don't have a 20 degree manifold) and possibly the fact that the clutch is maybe fairly worn out, maybe not. The bike barely moved. Am I way off in my ratio's?
Thanks, here is a video:
Your entire problem is you have a super worn out clutch as well as a worn out band brake. Engine seems to run fine if you set it and leave it alone.
You will never get power from the engine to the rear wheel with that worn out clutch, buy a new one.


Active Member
I can’t run the video just now. 6:1 ratio should be runnable. Every clutch needs some TLC, or replacing. Most bike drive trains have some friction/ binding that needs attention.