No problems at all on my machine
Known problems:-
Phosphor bronze bearing bush inside the main shaft first gear pinion wears.
Primary drive chain wears after 40,000 miles. The 8 x cush drive rubber wedges tend to harden, allowing some backlash. Take up the slack with shims or replace.
The rear wheel sprocket cush drive rubbers also wear at around 40,000 miles and are a pig to replace. I drilled out the centre and then chipped away at the outer for ages until it finally gave in - many spare hours needed for this job. If anyone has a technique for this job PLEASE let me know.
First impressions when riding the re-built machine are lots of backlash in the transmission, this is quite normal on these old Hondas.
Final drive chain
The original drive chain on this machine was a heavy duty DID/RK with 96 links and 530 size with a pin length (i.e. width) of 21mm. O-ring chains have a pin length of around 24.5mm, this leaves about 0.5mm or less clearance to the crankcase and may rub on an OEM rear wheel sprocket guard. It is safest to stick with the HD chains to avoid crankcase damage but be prepared to replace it every 5,000 miles or so. There are 520 size Gold O-ring chain and sprocket kits available in Japan, but at around £200 rather pricey.