[attachment=55590]IMG_20220808_182529895.jpg[/attachment I have a gt80 1980 4-speed put it all back together it runs great when I downshift I hear a grind noise if I upshift into first second third fourth etc there is no noise I'd hate to tear apart this motor and split the case again but I don't know how to adjust this adjustment arm screw how does it work well anybody got something out there I would appreciate your help thank you fellow Yamaha enthusiast..

Pretty unlikely that screw is in need of adjustment if it was ok before. It's purely a centralising screw so lif you got it in second, or third-- looking at the pins in the pic--then you can alter that scrtew if needed to get equal freeplay betweeb the claws & the pins if you moved the gear lever up then down. Only talking a millimeter or two, & just equal free play untill it goes to tur the drum pushing the pin--in both directions. So i'm no help haha. Changing down looking at the pic, moves the curved arm back, so can only wonder if its rubbing on the back of the clutch basket or even the kickstart gear of the basket.
----Forget all that above as these are 4 down not 4 up aren't they? so is it touching the crank gear & if so "why". What is it--GT80 or the likes.
Is there two ways the crank gear can go, like one way steps over a spacer to sit further in & other way just butts to the spacer, very much doubt that though.
I know the pic shows the pins in the drum end on but you don't need to take the end plate of & view them. You are just going by feel--similar free movement both ways before moving the drum/pin & turning the drum. Set that clearance if ya think it needs it but then move the arm both ways to see if it contacts anything that would be turning.