150cc gear case
 

I'm working on a carbide 150cc go kart. Had to remove the cluster gear to remove the final drive gwar. The foward gear gets out of sync when you turn the final drive gear and move the gear selector. When i removed the case there was a loose ball bearing that came out. The problem is not clutch related, everything was fine until i went to install the gears and cover. I don't know if there is something that keeps the forward gear always in sync when the selector fork comes back down to engage the slots.

This isn't specific to what you're working on , I never had one apart . But the ball bearing you mentioned : Could it be a detent ball ? A lot of shift able mechanisms use a spring loaded ball and notched shaft to hold shaft in a specific position .