Yamaha TRX850 Enthusiasts Forum

To get the valves checked on the old girl, But she was busy, so I took the bike to my chosen repairer and got its valves done instead.
Usual story, all the inlet were in fact only just closing and had to be reshimmed.
The carbs were way out of balance (even though they had been supposedly done previously). but what a difference, it now even sounds better idling and all that torque has returned. Its funny how you don't notice the gradual lack of performance until it is restored.
Well happy, great job, and well worth the money it cost. I am a clumsy bugger when it comes to engines and do not have the talent required to do jobs such as this. You can bet your cotton soxs I would lose that vital screw, into the internals.

An even bigger issue is that valves just at the edge of tolerances (clearance through guides and stretch etc) leaves the seats being compromised by any blow by of gases too. A stock TRX will loose a fair bit of power through compromised valve seating.
Doing the TRX valve train is not all that difficult compared to some bikes but if you`re not confident in your abilities it is best left to those that are.