Hej,

maybe this will be helpful for you:

Change sprockets pairwise. You will need two for the fifth and two for the second.
(second on clutch axle is pressed - but needs to be taken off to replace the fifth – dont’tuse it again!)

Make sure to measure distances and directions for second gear before taking it off the axle! If you don't know how to handle the press off/on than better ask a motorcycle or car workshop - with the right tool it is a less than 10 minutes job.

Check always condition of oil-pump and net-filter of pump intake befor you start to assemble the engine. Good oil supply is sooooo important for the bike. I never do a gearbox job without an oil-pump change. Upgrade it anyway if the pump is still a 5Y1-type.

By using the original parts for your kind of engine (43F) the gearbox should be good for a lot of miles.

The cheapest way to get more miles out of it: don’t go on too low revs in the fifth, and change the drive sprocket (15 now?) to a smaller 14.

Steps to an enhanced gearbox:

Yamaha used better gearbox sprockets when they start to deliver the XTs with e-start. As far as I know you may use these sprockets on your old axles (drive chain sprocket axle of updated gearboxes cannot be used because it is longer)– but you need to replace all gears.

On the later XT 600 Z 3AJ model (the one with the silver engine) they rised also
the turning speed (faster = more oil supply) of the gearbox by change the primary drive to
34/71 (yours should be 31/74). To upgrade your gearbox you need the clutch axle, the clutch
and the primary drive sprocket.

And again - an important and highly recommended update for the whole enginge would be to replace the oil pump – take the latest model (5-hole pumps work in 3-hole models).

Good luck!