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05 cr250f issues---any help appreciated

By bluethundaaaa,
in CRF250R & RX

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bluethundaaaa

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Hello all--

My wife and I own a track and her cousin's son (16 years old) bought an 05 crf250r new in 06. He has had nothing but problems (valves) with it and the latest round cost him $1200 and replaced the crank (I was not involved) but was put back together incorrectly.....anyway it does not run right and when it does run it makes a very loud knocking noise which I don't have a clue what it is at this point. I would like to help this kid out since he is a good racer (he took 2nd in HCMA in Montana last year), but he is basicly broke. I am a fair mechanic and I have access to a very accomplished mechanic if I can't fix it myself. I do all the work on my own bikes as well (06 yz450f, 06 yz85, 02ktm pro senior 50 lc), and the list goes on. So I have a two pronged question......Should we just not bother with it and try to trade it in on something more reliable or do you think it would be worth it to dig into it and attempt to fix it and then trade it in (would we get more for it)? He was told by the person that last worked on it that it needed a piston and rings (why he didn't just replace them I don't know), but does it sound like that could be the issue? I mean a piston and rings is an easy cheap fix but I find it hard to believe that it is just that.....

Thoughts?

thanks in advance

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rick413

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Believe it or not I have seen where the piston was installed wrong, the piston is

clearance cut for the valves, larger for ex. and smaller for int. it will run but knock like crazy. another thing is setting run out on the balance shaft is critical the shaft can and will warp and cause a knocking sound, hopefully the person who last cracked the cases on this machine knew what he/she was doing.

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Grand Master

Honda_250f_rider

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1) pull it all apart, checking all tolerances and everything...

2) Put it back together following the service manual exacally + replace worn parts

3):bonk:

There should have been no reason (almost no reason) to replace the crank, it sounds like the last person working on the bike was charging and replacing things that didn't need replacing.

I have 125+ Hours on my 06 and it is running strong. I rebuilt it 15 hrs of riding ago... I shimmed the valves for the first time at 98 hrs, and checked them at 122 and they were still at the top spec. I think if you change the oil and clean the airfilter more than you think you should, it will last...

Well, I hope you can get the bike fixed for that guy so he can get back to riding!, its sad how sometimes maybe you get sold parts you don't need or things just happen for no apparant reason... ...

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bluethundaaaa

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thanks guys!....I should have it torn apart and inspected over the next couple days. I will let you all know what the problem is. I really think that the last person that "fixed" it for him got in over his head and just threw it back together with some new parts and charged him for it. It is a bummer for the kid and I hope we can get it put back together for him and not cost a bunch.....since my wife and I are footing the bill.

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butt gas 300

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just stripped 05 crf250 that died at weekend,bigend failure.bits of metal everywhere in engine.think the bike had about 70-90 hours on it tops.owner pretty regular with oil and air filter maintainance.ive seen a 450 engine that done the same but had more time on it.seems a bit of a turnaround that some fourstrokes are now lasting less time than some 2 strokes.

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bluethundaaaa

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Way to Blue, If you need I have a stock piston and some gaskets I can send your way to help the kid out...

Rick413--WOW! thanks for the offer!. It is greatly appreciated. I will get it torn down and find out what the problem is first and let you know for sure. Should be Thrusday at the earliest and that is if he gets it to me tonight.

Thanks again.

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CRFredrider

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i have 2 05's. One got topend and valves at about 90 hours. the other is still going with at least that many and it had been ridden against the throttle stops way more than the other one.

I keep track of several 250F's and sometimes they go for a while and others times they don't. I have an 06 that i did the valves about 30 hours ago and the intake are tightening up again already. I don't know what they do to it in between when i get it, but if they are carefully and properly taken care of they do pretty well. I change air filter every ride and oil every three.

I have never rebuilt a bottom end on a 4 stroke unless they ran the motor out of oil. I have an 03 with 300+ hours on it that just gave up the crank after having an anthena piston put in backwards.

good luck.

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jhinderliter

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Believe it or not I have seen where the piston was installed wrong, the piston is

clearance cut for the valves, larger for ex. and smaller for int. it will run but knock like crazy. another thing is setting run out on the balance shaft is critical the shaft can and will warp and cause a knocking sound, hopefully the person who last cracked the cases on this machine knew what he/she was doing.

+1 on the piston

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Grand Master

El Marko

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As an owner of a 05 CRF250R that was raced religiously for 2 years, I can tell you these bikes are reliable. Mine needed essentially nothing in 2 years and 100+ hours of mx (all racing, no trails). Valves stayed in spec and I finally had the piston/rings replaced at the end of the season because I was just starting to see a trace of smoke.

The first guy who worked on this bike probably messed it up and won't fess up.

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