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'02 xr250r smoking

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My dads '02 xr250r is smoking terribly on cold starts. I know it is probably just the valve seals but is it a good idea to do an entire rebuild? I don't believe it has ever been rebuilt before but it is not ridden hard and we keep up with clearances and such, thanks all

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If you think it's just valve seals then I assume it burns off pretty quick and clears up? Or does it smoke constantly, all day?

Does it go thru a lot of oil, that you have to be vigilant to watch the level?

Is it routinely fouling plugs?

If not and it has good compression and runs well otherwise, I wouldn't feel like I needed to be in a big hurry to rebuild it.

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yes it does clear up and as for the oil level, It doesn't seem to be burning through much as far as I can tell. and no it is not fouling plugs. compression is borderline

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compression is borderline

When you address that , slap some new valve seals in.

How many kicks does it take you to get the thing started ? If it takes you a alot of times or you do the pre charge method with the decomp/kill switch its gonna be rich off the get go and that can make it smoke too. Once the excess fuel burns off , the smoke goes away.

Edited by r00t4rd3d

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it takes a good bit to get it going and i dont use the precharge method. Should I go for a piston and rings as well?

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Matters how it looks. A good machine shop will be able to tell you everything. The valves could be the cause of the low compression.

Start looking for a shop in your area that knows bikes. When you tear it down , just take the head , cylinder , piston , etc to them. Posting pictures here will get you plenty of feedback too.

If your kicking 10-15 times to get it started , the smoke is from being flooded though I would imagine , okay as long as it goes away.

Whats your plug look like ? Pic ?

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Do a two stage compression test and you will have a better idea of what is causing the smoke. Valve seals are a weak point in these engines and a little smoke, if the compression is good, is not a reason to rebuild. After all the smoke indicates that the valve guides are getting oil.

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DSC_5503.jpg

DSC_5502.jpg

DSC_5501.jpg

DSC_5497.jpg

It must be the seals. the right exhaust valve face is dry because its on the high side of the bike when its on the kick stand (alot of the time). The top of the piston is amazingly goopy

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i am a 14 year small engine mech and i suggest new valves stainless steel with new springs if they are not seating properly and the seals . new piston rings and piston if top is badly pitted. this will solve your problems and prevent further complications!

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piston is not pitted. What is a good method to clean up the carbon in the mean time?

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piston is not pitted. What is a good method to clean up the carbon in the mean time?

Wire brush?

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Just make sure its soft and your not removing any material besides the carbon build up.

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Take the piston out and look at it. See how the skirt looks. Lets see a pic of the cylinder bore too. You should really take it to a engine shop cause they can measure the piston and cylinder and tell you what you should do. Bore , rings , piston , etc.

You dont wanna see this real bad :

70201195702924956999941.jpg

If it was mine and I had the money , I would get a valve job with $Kibblewhite$ vavles and springs , seals , etc. New piston and rings and what ever the machine shop suggested with the bore.

Art :

0612em_06_z+cylinder_head_honing+crosshatch_angle.jpg

Find this guy ^^

Edited by r00t4rd3d

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Im in charleston Sc and I just dont know of any good shops around here, theres not a huge biking scene. I'm having trouble getting the cylinder to break free from the crankcase

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Im in charleston Sc and I just dont know of any good shops around here, theres not a huge biking scene. I'm having trouble getting the cylinder to break free from the crankcase

If I was already in that stage of disassemby, I'd just get new parts and do it myself, there are a lot of online shops that can re-sleeve your cylinder and do maybe a top end? I'm not a fan of local mechanics or at least the ones I've met don't know much about our kind of bikes, and XR's are pretty common bikes! Good Luck! :thumbsup:

Piston and rings: www.rockymountainatvmc.com

Re-Bore-Sleeves: www.lasleeve.com

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when i do myne i soak in diesel or gas for 24 hours and then use a wire wheel eather on a bench grinder or a hand held. but the diesel is not a mandatory item i just use it because you DO NOT use the wire wheel anywhere but the top of the piston and some times the sides of the piston can get a little banged up if it had piston slap for a while.plus the sides of the piston are a little more fragile (you dont want a piston skirt breaking). hope this helps.

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your cyclinder looks good from the picture it just looks like you had piston knock. i would get a new piston ring set and make sure you get a new wrist pin that could be your problem. when you bring your cyclinder to the dealer they will be able to measure your bore and tell you weather you need to bore to the next size or not! the size of your original bore should be stamped on the side of the cyclinder hope this helps cheers al!!

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