Gear box

Hello
Ok I have a stupid question Is it possable to fit a 4 speed semi-auto gear box to a st70 if so what gear box fits and is it a easy job

Yes it's possible, relatively easy if your confident splitting the crankcase.

Later z50s have 4 speeds that I assume fit.
Ss50, ct70h and atc70 should fit, just make sure you check they are 4 speed as some ATC's and CTs were 3 speed.
AHP do a four speed that fits which is relatively cheep, these also exspensive aftermarket kits if you got the cash.

Hi, i have mounted severals of these gearboxes in rebuilt and tuned engines, and so far they seem to work very well.
Latest engine i've put one in was a machined z50 case
, to fit in 54mm piston and the MW 4V head (119cc).

That engine Rock, i can say

//Jörgen