CRF250 Pistion Cleaning/Inspection ??

Been doing work / cleanup on my 05 crf250x carb. Took a quick look at my intake valves and there is quite some build up on the top of valves. Could be gas vapor deposits or oil deposits.

2005crf250xintakevalve-2.jpg

My plan is to remove the entire head and rebuild. Or purchase a new 07 CRF250R Head with Kibblewhite Valve & Spring Kit.

MY QUESTION TO ALL IS:

Since I will have the head assembly off what are your recommendations with inspecting and cleaning the piston????

Thanks for your input and advice.

I think the valve seals are leaking and the oil is getting to valves?

Thanks Rubu.

I am learning more and more about my bike. What causes them to leak?

Since I am the 2nd owner I don't know the maint history. But I do maintain my bike very well since I have had it. New air filter every ride and change oil every other ride.

The leaking can result from seal wear or seal are old and hard, they are made from rubber.

If you have new head there are new seal so no worry about them.

If you dont know how much the piston has been driven I recommend that you change the piston at the same time as the head.

So would you put in the stock 12:9 1 or should I go to a 13:5 1?

You should replace the piston. Especially since you dont know how many hours are on it. Stock would be fine. 13.5:1 would give you a little more grunt. If your looking for more power get your head ported.

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