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New top end at 82 hrs-Stock valves perfect!

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I just finished putting a top end in my '04 CRF450 with 82 hours on the bike. The piston still had the factory black coating on the skirt, there were no signs of blow by past the rings, the cylinder was in perfect condition, the cam lobes showed no wear and the best part is.....all 4 valves were still in spec and looked great. I cleaned everything up, replaced the piston, rings and pin and installed new intake and exhaust valve springs. I will continue to use the stock ti valves until they show signs of wear. I am a believer that the valve issues have to do with running these bikes near the rev limiter and weak valve springs that allow valve float.

In case you were wondering: I am a Vet A rider. Only ride moto. I clean my air filter after every ride. Use Ready Filters with Maxima FFT (I do reuse them). I change my oil every 8-10 hours. I use Torco T4MXR :) on the engine side and Torco MTF 80wt :) on the tranny side. I do not run this bike near the rev limiter (there is no need to). I check my valve clearances every 20 hours. Never had to reshim (always have been in spec)

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Right on. My 03 has a total of about 175 hours on the enttire motor. I replaced the top end after 150 hours. I have never had to adjust my valves yet. I am very pleased with the bike. I clean my air filter every time out. And I change my engine oil ever 5 hour and my tranny oil every 10 hours. I keep it off the rev limiter as much as possible. I think with routine or more than routine maintenance will keep these things in good running order. By the way most of my riding is desert and dunes.

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Just checked my stock 02 valves last week and they are still right on. About 175 hours on the top end, and I am not worring about replacing it antime soon.

I short shift and stay off the rev limiter as much as possible, which are the keys to making this thing alst I think.

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My 02 had over 200 hours on it when I rebuilt it the piston looked nearly new,I had one intake a little tight ,I replaced both intake valves with oem valves,new springs and keepers and guide seals all the way around,ground the exhaust valves,it is still running well.

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My 2003 had well over 100 hours of nothing but hard moto on it when I replaced the piston and rings. Valves and head were perfect and I never had to adjust valves during that time. In fact I sold the head with valves and springs to a guy here on TT and as far as I know it is still running fine...

I too agree with the rev limiter issues, namely being on the stock valve train if you run it on the limiter, you WILL have accelerated valve wear issues...

I also cleaned my air filter every ride, changed oil every 3 rides, and ran the piss out of it. It liked it. :)

I am following the same regimen on the 250F. So far so good, it had about 20 hours on it when I got it and I have put about 8 hard moto hours on it and valves are still in spec. :) The guy that had it before me basically followed the same maintenance schedule I think...mxaddict?

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