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Hi All,

So my MC19 seems to burn oil, mainly on the over run.
I was thinking Valve Stem oil seals but I read here that there's no real side load on the oil seals so probably wouldn't be them.

I have noticed that there's always quite a bit of oil in the air box from the breather. Is there something I need to look at to stop it blowing oil back into the air box.

Many thanks in advance

Phil
 

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1. Do compression-test, report numbers here

Typically crankcase is under vacuum. This helps generate extra power because pistons aren't fighting pushing air around underneath. Vacuum is generated by connecting crankcase to vacuum source, airbox is typically good spot.

However... if you get ring blowby, this pushes extra combustion-gasses past rings and into crankcase. Negating benefits of crankcase vacuum and pressurising it to push oil-vapour into airbox.

Compression-test will determine condition of rings and their sealing. Might need to re-ring engine.
 
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