Interseting thread, which gives me some hope... My 21 is horribly vibey - to the point I don't like to ride it - but there is no noticeable noise from the crank (mains sound fine etc.) and I have receipts that suggets that the motor was rebuilt with a refurbed crank less than a thousand km's before I bought it. If there's a dot I'd very much think it's there for a reason? - although a machined-in mark is more common in such applications for the obvious reason.
Does anyone have a japanese workshop manual? The motor rebuild section should indicate if it should line up with something I'd think?
Cheers
Wb