my clutch pully is in really bad shape.
it no longer has the starting function and just freewheels then when it heats up it does what u just described but the starting function works again.
i start it with an allen key.
wari i still find it hard to beliive ur stock bike goes 50, did u build a pipe or what, or is it just that pully variator thing u made. ported stock setup, carb??