Recently acquired 1976 Yamaha YZ175 in pretty good condition but has trouble shifting from 2 on up, just wont do it. New oil, new clutch fibers, new clutch springs, existing steels. Ask only starts with a bump-start, after its warm it starts with the kick starter (if that info helps). It looks like there's a shifting adjustment that can be made in the service manual that I haven't tried yet. Any ideas? Thanks.