1969 Rupp 2 speed slipping-need help

i have a 1969 all original Rupp Roadster. I have issues with the transmission slipping going from 1st gear to 2nd gear. I replaced the spag bearing the first time and it was perfect. 6 months later it was doing it again so i replaced again. It is better but still have to feather the gas to get it to shift. All clutches are original. Any suggestions

Craig Smolen


Well-Known Member
Those 2-speeds were known to be finicky with age. I'd probably check the shoes and the inside of the secondary clutch to make sure it's grabbing like it should
Are these things readily available? Im not sure I quite understand how these work just yet... I assume because the 2nd clutch engages at a different rpm than the 1st it would have different spring rates?


Active Member
These 2 speed overrunning mini bike transmissions are some of the most interesting "systems" to ever come out for the mini bike world IMO.

I've never ridden one or even seen one in person but it sounds like the 2nd clutch is slipping when it's approaching it's stall speed.

A failed one way clutch or sprag would most likely completely disengage and not exhibit a "slipping" type scenario.

red baron

Active Member
I've never heard of this system until a couple of days ago. I get the concept which is genius in it's simplicity but I'm not sure about the components. Is the jack shaft clutch a standard centrifugal clutch? I would imagine gear ratios would be key in shifting characteristics.