I'm back,  tired of me yet?  The next chapter in the "free bike" saga  pt 2.

('72 250)

on the shifter ( diagram there is an eccentric peg (Adjusting screw 90149 06017) in the shift lever.It seems this is for the return to bear against.  the question is, why is it eccentric and what do I look for in setting it?

thanks
Rich

In an ideal world you shouldn't need to alter it, but it's for equalizing maximum travel both ways for up & down change. & when ya happy with that then there's a very small eccentric on the arm locked by a 6mm nut--10 spanner size which equalizes it over the pin on the drum--not neutral but second third fourth or you get mucked up by the neutral gap--so that one sets the gap each way before it picks up the drum pin. Leave it alone if you can but is handy if you've crashed off & over-stressed the gear lever & bent things.

Manual in Tech Library has instructions.  As RT325 said, best not to mess with it most of the time.  Keep in mind these transmissions need to be spinning to shift gears.  It's normal for it to be difficult/impossible to shift through gears with engine on bench or while parked.