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The TTR250 FAQ web pages -> TTR250 -> Repairs and maintenance -> valve stems white?
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wizz


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valve stems white?
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Hi my bike has been running lean,bog standard, done all usual checks, stripped carb blew with air line, rubbers fine,no exhaust leakage, new plug,when I removed the down pipe I noticed the valve stems are covered in a white powder.don't know when the clearences were last checked? my bike has 29000 k. Could the clearences be my lean problem? many thanks Mark



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Halesowen West Mids.UK.
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It may well be the problem if it is accompanied by hard starting or backfiring/popping. If you have none of these sypmtoms than it may be safe to say either the jets are wrong or the diaphragm pump is blocked. It would be worth checking valve clearances though.

It may be worth checking that diaphragm jet is not blocked or the pilot curcuit, if you have not done so already.



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There may really be nothing wrong with your white exhaust stem. confuse

Exhausts are meant to run hotter than inlet and are designed to cope with high temperatures. wink

As long as your engine's not unduly complaining with undue knocks and banging you may do better to carefully monitor it.

Don't worry yourself unduly by looking up the exhaust port and being amazed at a natural sight. hmm

If it's not bust then it don't need mending. no

Martyn

 



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wizz


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thanks just worrying about nothingno



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Wizz, I just Googled "white exhaust valve stems" and found the following articles:-

CLICKY ONE to Thumper Talk

CLICKY TWO to Adventure Rider

CLICKY THREE to (curiously) Modern Vespa

They confirm that if the engine is running otherwise then it's likely to be the hot exhaust causing the whiteness and nothing to worry about.

Funnily enough they seem to use the phrase I commented on, "If it ain't bust don't fix it".

Martyn



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East Budleigh. Devon
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Well I'm just glad my valve stems aren't white or it would suggest a lean condition or valve re-shim or reseat/ valve stem seals. Either that or I need to ride it more often wink

This is what used valves should look like..

 After a clean... biggrin

 

Jarrah

 



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