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Old 02-02-2010, 07:32 AM   #1
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Default Exhaust turning red

Hello I have a 2005 yz250f, it has always ran really good, I cranked it up today and the exhaust is turning cherry red I know this can happen if it is to rich but it don't seem to be. Any help would be nice. Thank you Jeff
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Old 02-02-2010, 07:44 AM   #2

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Sorry to tell you this Zane, but your 250 four stroke is about used up.

Since to make the same power of a 125cc two stroke, all the engine internals on your bike weight about half as much as they should, and as a result last about half as long.

A new MX 250 four stroke lives at around 13,000 rpm, and as a result blows up with the regularity of Old Faithfull in Yellowstone.

Do a leakdown and you'll most likely see one of the exhaust valves is leaking, and dumping some of the intake charge into the headpipe, causing it to burn there, instead of in the combusiotn chamber.

I could be wrong...but most of the time I'm not....

Good luck. And if you're not a racer you might want to get a used two stroke, they last a lot longer with minimal maintenance.
A gun is a tool, Marian; no better or no worse than any other tool: an axe, a shovel or anything. A gun is as good or as bad as the man using it. Remember that.
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