The ATC70 had two different crankshafts. The 78-80 has a shorter crank than the 81-85. please check your engine number and choose the correct year before purchasing.
If you already have a TB 88cc kit you will need to purchase the new stroker piston/rings
When purchasing the entire big bore/stroker kit together we will provide the correct piston
The 6volt high volume oil pump is required with this crank. You will also need to upgrade your clutch.
Includes center case gasket.
Installation of this part requires the engine cases to be split. Unless you are very experienced at working on these engines, we recommend having a professional technician do the work.
