Britt Boyette said:
I know they say to replace the valves when they go to Zero but, what do they normally run. I'm right at .006 on my 03 CRF 450R. Also, do the exhaust valves seem to wear quicker than the intakes or is it the other way around?
Honda OEM intake valves are about $50 each, valve springs are about $7 each (yes the springs need to be replaced along with the valves every time ;) )
The OEM exhaust valves don't suffer the save face recession issues as the intake valves, but when guys run pump gas the deposits left behind will erode the exhaust valve face and destroy the seal. The exhaust valves are steel and the face can be re-ground with the proper equipment, but if the erosino is bad enough (very common) then the margin on the end of the valve will be too small and the valve will be unusable. It's easier to just replace the exhaust valves in most cases.
For most guys changing over to Kibblewhite stainless valves and their spring kit is the best solution for long term reliability, and ease of maintenance over the life of the engine.
No matter what valves you use, if you have a couple of seasons on the engine it will need a valve job and you'll also need to carefully check the exhaust guides for wear. Excessive wear in the bottom third of the exhaust guides is a common problem due to the high ratio roller rocker Honda used. You also need to look closely at the roller itself for excessive wear.