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New here with a few questions on an 06 CRF250X

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Hey guys I am new to this whole four stroke deal. I used to race but had a 2 stroke, my dad did all the rebuilds and knows his way around a bike real well. My question is how do you know a crf 250 needs new rings, how hard is the job, how hard is it tune up the vavles, and how much would new piston and rings cost? Sorry so many questions but my brother has a chance to buy one at a steal but the guy says it needs new rings.

Thanks

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Grab a owners manual and service manual, you can buy the PDF's online for less than 10 bucks. As far as parts go, parts unlimited or check out your local honda dealer. Once the valves are set after you put the new rings in they don't need a whole lot of adjustment with the stock cam. But if you ride wide open with a R or Hotcam all the time they will need more service. Hope this helps a little.

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The way you check for ring wear is with a compression tester, same as any other bike. It is easy to check or reshim the valves if you follow the how to in the sticky.

http://www.thumpertalk.com/forum/showthread.php?t=179775

Parts for top end are around $200...piston, rings, wrist pin, circlip, gaskets. You can get the head refurbished with stainless steel valves installed for around $500. SS valves last many times longer than the Ti ones. Once the OEM Ti valves start to wear, you can reshim them until you run out of available shim sizes, but each re-shim will usually net less operating time between intervals.

I have an 06,with around 150 hrs. At 110 I had the head done and sunce I was in there replaced the piston and rings. The only other maint I have done to the bike is regular oil changes, cleaning the air filter, tighten spokes, adjust chain and I had to replace the linkage bearings due to corrosion.

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If your mechanic(dad) is used to building two strokes, he should have no problems with a 250x. Only thing for him to worry with is timing. Plenty of posts on it , I wrote one within the last week.

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Also on 4 st a leak down test can be performed. I have never done one, but I think it checks the seating/seal of the valves.

Some claim this test more important than compression check.

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Also on 4 st a leak down test can be performed. I have never done one, but I think it checks the seating/seal of the valves.

Some claim this test more important than compression check.

Yes, a compression check is a crude way of checking how well the cylinder is sealed. A leakdown test is more accurate and lets you know where the leak is.

What you do is pressurize the cylinder and then see how fast it leaks down. With a good ear (or better yet a stethoscope) you can tell what is leaking by listening for the escaping air (if nothing from exhaust or intake, then it's the rings that are leaking).

Jim.

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It would be silly to take the top end apart without putting in stainless steel valves, and making the bike relatively bulletproof.

I would be a little surprised if it truly just needed rings. That seems like an over-simplification by the seller.

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