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how many hours to expect from fresh valve train ?

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If a proper valve train rebuild is performed, how many hours can you expect to get from these bikes ?

I know there's plenty of you who have gone through this a few times, hoping you'll share your experience.

Thanks

Edited by dieseld
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i have had to replace just the intake valves in my 07 and my 08 around 100 hours. i also replaced the crank and piston at the same time. but i had the valve seats cut not replaced. my 07 has 150 hrs since the build right now and everything is all good. no valve movement. i used stock valves and piston.

i didnt replace the exhuast valves becuase they wernt bad. there 250hrs on the exhuast valves right now with no problems.

im and agressive b rider that spends more time on the rev limiter than i should.

i feel if the guides are good and the seats are cut right and you clean your airfilter right you can get some good hours out of the new valves.

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Unfortunately, its a loaded question. I've heard of people get up and over 200 hours on them and I've heard of people getting 30 hours out of them. I don't know much about the 04-05, but I can speak from experience on the 06-09. The air box to air boot seal is really bad and that's where 90% of the issue is, as to why the valves go bad. Dirt gets sucked in through there causing the valves to prematurly wear. If MotoX_2005 reads this, he knows more about the 04-05 than I do and maybe he can shed some light on if its the same set up with the same issue. Did you consider going to the stainless steel valves? I don't care for them, but some guys say you don't notice the difference. My kid noticed it right away so I've stuck with the stock Ti valves. I got 116 hours on the last set and they were still where I set them at 2 hours. Thats on his 08. I could have re-used them, but I decided to replace them when I rebuilt the bottom end. I do know that they make a much better than stock Ti valve also, but my guess is that they are much higher in price. Maybe worth it to you.

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It really depends on how much are you willing to spend, the best set up for you being an intermediate + rider would to throw a 07+ head on it (i prefer the modded 09 head the most but if you want to leave it stock the 07 head was a good bet) if you want to keep the head set up you have now and spend the $450 for a top end including seats cut and seal up the intake good you can look upwards of 60 race hrs with proper maintenance, if you ride really hard you may see less.. my stock 05 had 120 race hours on it before the right intake sucked..

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As many hours as it takes for you to feed it dirt. Feed it dirt in the first hour, they'll last a couple hours. Kepp the intake track SPOTLESS and they will last.

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I have always heard you can get a lot more time out of the engine if the carb is jetted correctly. Generaly richer as opposed to lean, which is hot. Heat kills engines and causes the valves to stetch. Crf X's in CA. came super lean and the valves would go bad rather quick. I believe the carb has quite a bit to do with it. Thats my understanding.

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generally motors running leaner will make more power.. but yes excessive heat will make parts wear faster, on the 4 strokes its not a bad thing until you start overheating, having detonation or pre-ignition.. on a 2 stroke running lean is a bad idea..

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