Valves?

20-30 hrs. and you should check shim clearance. If still within OEM specs, nothing needed.

If little clearance you can re-shim.

If no clearance disassemble head and inspect valve seats and valve seat margin.

You would probably be around $300-$500 for new seats and valves.

This should be in the 'Race Shop' forum.
by 'done', do you mean replaced or re-shimmed?

How many hours is on your bike, and have you kept the air filter clean and the jetting correct?

I just re-shimmed by bike. Literally 30 minutes ago! Bike had 2.4 hours on it and both intakes were a little out of spec (tight). Exhausts valves were both within spec. The manual said to check the clearances after an hour!

It was actually pretty easy to do and not as complicated as I thought. I just checked out a YouTube tutorial first (and referred to it during the job). When I do it next time it will take no time at all.

Needed to buy a shim set first though, and my first calculation of which shims to go to still was a little tight so it was nice to have all the sizes to hand.

Buy a hot cams shim kit,they are cheap.

If it has gone to zero clearance on the intakes pop in a 4 thousands thinner shim,I use a micrometer to measure them.

You could put in a 2 or 3 thousandth thinner if you want and recheck. I think spec is 2 to 4 thousandth.

If it is hard to start that is a sign it is gone to zero and what happens is carbon builds up on the valve face . Even if you set the correct clearance it will change once started and that carbon buildup cleans off,recheck your clearance after to be sure.

I set my valves on the largest gap the spec calls for,the engine will make more torque with 4 thousandth than with 2 thousandth clearance because the valve gets off the cam earlier ,if you want rpm go with the least gap the spec calls for.

The exhaust valves are not titanium and dont wear like the intakes do.