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2002 XR250R problems, advice?

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Went riding memorial weekend and after about an hr of easy riding she started to smoke like a chimney then it stopped. She was still running good but I just rode it back. Went to start it the next day and now everytime after it warms up it smokes like a chimney, could use it to keep mosquitos away. Any advice on starting point for things to check? Already tried changing oil and checking level. Also note tailpipe seems oily/ sooty and is harder to get started now.

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Since it still seems to be running ok, instead of a broken ring or something like that, perhaps a bad valve stem seal or guide.

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Ok, if it were oil rings that wouldn't necessarily show up on a compression test would it?

I wouldn't think so. Oil on the cylinder wall would help compression I would think, as opposed to seeing a compression drop.

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I checked valve adjustments today. They were tight but it didnt help, still smoking bad. Its my first time digging into top end, is there supposed to be oil under the valve adjustment covers or is this a sign of leaking seals or guides?

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I tried checking compression but the gauge couldnt get in there and get a good seal, is a leak down test a good way to check valve seals? If so is there somewhere that explains how to do that, im not getting anything in the search

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Oil under the valve cover caps is normal.

I can't think of any forum thread right off that describes how to do a leak down test. My first thought is to search Youtube for a video. Lets see if anyone else responds that knows.

That the plug wasn't wet is good, but the fact that it was black/carbon covered is of no help in determining anything because its probably been in there forever. You'd need to put a fresh plug in and look at it after a short run to get an idea of current running conditions.

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Does the "oily/sooty" tailpipe smell like fuel? Have you checked the carb? Choke? Is there fuel coming out of the carb overflow?

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Theres no fuel coming out of the overflow, would it smoke that bad if it were a fuel issue? Its white smoke and the tailpipe from what I can tell smells more like oil

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Smoke from a fuel issue is usually black. White smoke is usually considered to be water related. Are you sure it doesn't have a blue/ black tinge to it, making it more oil related.

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What kind of engine oil is being run in it?

Check your fuel for water contamination. Even tho its new fuel, you could have got some bad gas.

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Running maxima 10w40 synthetic blend, fresh change and filter didn't help. I dont think its the fuel I used same gas from same can in my rider with no issues.

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Is it possible that what BR said true? Could the bike have been run out of oil? Check your oil strainers while you're at it.

 

Until you drain your fuel and put in a gallon of fresh, 100% high octane you haven't really eliminated the obvious possibilities. Drain the carb too.

 

What's the color of the new plug after a short run?

 

cheers

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I drained the gas and put in fresh 93 octane gas and nee plug, first pic is after a short ride and second is new plug from idling each one was a brand new plug. They are burning white with some darkness around the electrode, its interesting because the old plug I took out was black. Even with new plugs and gas and burning white its still smoking like a chimney and never stops, keeps skeeters away. Now any suggestions?

1401926068643.jpg

1401926110428.jpg

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A "leak down test"can help pinpoint the problem.

A new and properly worn in engine will have a maximum of 4% leakage.

It will never be 0% because rings have gaps in them

10% leakage would indicate you have a problem that needs correction soon.

With more than 10% leakage it's really not going to run as well as it should.

So as an example, let's say your leak test showed that you had 10% cold but 6% completely warmed up.

The leakage has to be at any of the valves (Intake ports or exhaust ports) and/or past the piston rings (crankcase breather/vent hose)

It's also possible to leak past a cylinder head gasket. But not likely in your case...

So since yours smokes so bad it's likely piston rings.

But let's say you only had 6% leakage from worn rings only, no valve leaks at all....

Since 6% is not very much, then IMO, your valve stem seals could be hard, brittle, and not sealing as well as normal anymore.

If that's the case, pull it down and replace the stem seals (and piston rings since your right there anyway)

At least remove carbon from valves and lap the valves to cylinder head if they all look ok.

(DO NOT USE A MOTORIZED WIRE WHEEL/BRUSH TO CLEAN THE CARBON FROM THE VALVES AND SEATS)

Hopefully this helps

Edited by adnohguy

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