05 CRF 250 valve shimming problems.

[Willum]

I'm working on a crf for a buddy and we went to adjust his valves and I cant get the smallest feeler gauge under the intake cup and the cam. I've read that these bikes had problems with crappy stock valves that "cup" into the valve seats. My question is that is the problem just with the intake valves, or are the exhaust just as crappy. We plan on replacing them with Stainless Steal ones.
My other question is about shimming after valve replacement. Is there a standard shim to be used with a fresh new valve in place?
Thanks for your help.
Bill

[Woody_393]

I'm pretty sure both Intake and exhaust are Titanium, which is why they don't last quite as long as they should. Though honestly I can't remember if the exhaust or SS or not. I'm sure someone else that can remember will chime in.

As far as shims for the SS valves, no their isn't a standard size, you'll just have to guess on what shim to start with and then go from there. I'd personally start with the biggest you have (if you don't have a shim kit) or go right in the middle if you do have a shim kit.

[AgentSmith]

Only the intakes are the crappy Titanium. The exhausts are a two piece steel/stainless steel valve. They don't wear on the face like the Ti valves do, however due to the side loading applied by the rocker arm set up they tend to eat guides.

So...
When doing a valve job always have the seats re-cut to renew the sealing surfaces and angles, and have the guides checked and replaced if needed.

If the exhaust valves are still in spec, they can be reused.

When putting in stainless intakes, there is no standard shim, but I usually see 1.80-1.85mm as the necessary shim.

[Willum]

Awesome! Thanks for the quick and great response!