[nuss250crf]

Hi first post so be gentle 😋

Righ i recently took ownership of a 2005 crf 250. bike runs like a champ but once its dropped or stalled during a race it wont start again untill its cooled 😡

I checked valve clearances last night and both exhaust valves have gone loose, the Left - 0.025 and Right - 0.023. The left inlet is loose at 0.009 but the right inlet is tight at 0.000!

Now i understand they tighten up but why would they be loose on 3 and tight on 1?

Any help appreciated 😊

[nuss250crf]

Well I've shimmed it back into spec so will take it out this weekend and see how it performs then re-check the tolerances.
If they are out again it looks like it was shimmed to sell on and will need new valves 😁

[crfsonly]

Welcome to CRF's Only! Glad to hear you've got them back in spec. The right intake that was tight will likely tighten up again after a few engine hours. So, do go too far from your staging area. The exhaust valves are stainless steel and as such are more durable than the titanium intake valves. The intakes are usually always the first to start tightening. Yes, you may have been a victim of a "shim and sale". It happens. We offer full head and valve services if you have any questions let us know.

Again, welcome to CRF's Only.

Ken

[nuss250crf]

Thanks for the input it's much appreciated ☺

What could cause the other 3 valves to go loose? I was wondering if it was just a case of bad shimming in the first place that made them all out of spec! Once re-measured after Sundays outing I should hopefully know more.

[crfsonly]

most likley they were incorrectly set the last time.

[nuss250crf]

Well checked the clearances again today and found what I expected, the right clearance had moved (still in spec tho).

I've pulled the head off and found the right valve very worn! The left seems ok but do I change as a pair? The valve seats don't appear to have any wear at all.

I've priced the titanium valve kit from your site and its a good price if I don't get hit with import tax to the uk lol

[crfsonly]

you must replace them in pairs. the seats must be professionally cut to maximize valve durability. if you don't have the valve seats professionally cut you'll get far less engine hours your new valves. you should also replace the spring, retainers, and cotters.

you can go with the titanium intake valves or you can switch to the Kibblewhite stainless valves. The KW stainless valves will provide much longer valve life over the titanium valves.

ken