Eppo Karsijns sent me this:
Some more news from the top of Holland.
The starter gives a lot of trouble as it I read reactions on your site.
Here is my solution. It's only fifteen minutes work annd kosts only a few Euro's:
the starter wire from connector (6).
Remove bolt no. (4b)
remove both bolts no. (5) and no.(4a).
the tail (1) and the body (2) but keep them together.
planetary housing (3) is connected to the engine from the inside.
It will not fall on the floor!
shim (7) (Genuine Yamaha no.: 1J7-17537-YO-30) in front of the body.
Attach it with some grease.
all parts in opposite order.
shims are not originally made for this engine but for a
four-cylinder supersport from the eighties. (Which one,
I don't know. This may be a nice prize question.)
minutes and, BINGO!! No more starting problems!