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Approximate Hours for Top End

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I have a 05 CRF250 that my son rides. We have a hours meter on it. Looking for experienced opinions on how many hours we can safely squeeze out of a top end (and valves). I have a 03 CRF450 and have a good idea when top ends are due but the hi rev's of the CRF250 concerns me about hours. Thanks in advance for the advice.

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i had about 200+ hours on mine before we did anything and the piston still looked fine

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i had about 200+ hours on mine before we did anything and the piston still looked fine

Does "top end" include valves? I would think on a moderately ridden engine you could go 200 hrs. Valve would likely go first. At least in my case.

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my 06 has 85 hours and not a valve has moved and the piston and rings are still a-ok

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Personally, if the bikes ridden hard, I wouldn't go more than 50-60 actual hourmeter hours at the most.

When I rebuild mine I recut the seats, install new OEM intake springs, valve seals and leave the valves alone since I have never had a valve problem.

Piston, rings, wrist pin, circlips and gaskets and you're good to go.

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LOL! I saw this thread earlier and read some of the responses and I was going to say something but I knew Fred would have something to say about this. Nice job TJ, you know your stuff that's for sure! :thumbsup:

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mine is estimated. i figured that there are about 48 weeks in a year. i ride 2 times a week for about 4 hours. that would be roughly 350 hours on my engine in 1 year correct? :thumbsup:

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Personally, if the bikes ridden hard, I wouldn't go more than 50-60 actual hourmeter hours at the most.

When I rebuild mine I recut the seats, install new OEM intake springs, valve seals and leave the valves alone since I have never had a valve problem.

Piston, rings, wrist pin, circlips and gaskets and you're good to go.

Fred, you recut the seats and leave the worn(relatively speaking) valves in? That doesn't seem right :thumbsup:

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If the valves didn't lose any clearance they're not worn.

I've done this on all my bikes. My 02 CRF450 had over 300 hours on it with the original valves. I sold my 04 with around 130 hours on it with the original valves, and my 05 has almost 90 on it.

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mine is estimated. i figured that there are about 48 weeks in a year. i ride 2 times a week for about 4 hours. that would be roughly 350 hours on my engine in 1 year correct? :thumbsup:

Is your engine running for 4 hrs each time?

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If the valves didn't lose any clearance they're not worn.

I've done this on all my bikes. My 02 CRF450 had over 300 hours on it with the original valves. I sold my 04 with around 130 hours on it with the original valves, and my 05 has almost 90 on it.

That 04 has way more than that now and I don't think he has even checked his clearances since he bought it from you. :thumbsup:

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Is your engine running for 4 hrs each time?

pretty much.... thats at race speed too

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watch out SMF, 723onYZ250f might try and start stuff, theres "no way you can get 200 hours out of a stocker"

my bike went on 200, 3/4 compition riding not that me or the kid befor me was pro, it wasnt babied, the only thing wrong was i had bad piston skirt wear

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watch out SMF, 723onYZ250f might try and start stuff, theres "no way you can get 200 hours out of a stocker"

my bike went on 200, 3/4 compition riding not that me or the kid befor me was pro, it wasnt babied, the only thing wrong was i had bad piston skirt wear

:thumbsup:

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TJ just wondering, why do you cut the valve seats if the valves are the same. I get new ones and get them recut so I don't know.

I have a 05 CRF250 that my son rides. We have a hours meter on it. Looking for experienced opinions on how many hours we can safely squeeze out of a top end (and valves). I have a 03 CRF450 and have a good idea when top ends are due but the hi rev's of the CRF250 concerns me about hours. Thanks in advance for the advice.

get an hour meter so you can be completely sure of the actual ride time you have on it.

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TJ just wondering, why do you cut the valve seats if the valves are the same. I get new ones and get them recut so I don't know.

get an hour meter so you can be completely sure of the actual ride time you have on it.

Because the seats still get deformed, so the seating surface isn't to spec.

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