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Worn valve guide
The Shop
Nothing clutch related should affect your top end.
Hello guys , I have the same problem with mine crf 2018 , did somebody find some solution ? im suspecting to piston rings , because piston is in factory spec and the head is seems fine ...thanks in front
Is it smoking out one side of the exhaust or both?
It is smoking and spitting oil only on right exhaust, valves are fine , valve seals new , by the carbon on the right exhaust valve (any other valve is clean) i could tell that is coming from the combustion chamber, cilinder is good , piston is 0.05 from cilinder which i think is also fine , only thing that I could notice is that the compression ring joint was near to that valve, so I`m suspecting on the piston rings... the engine worked fine before , I changed con rod, bearings etc ... didn`t change the piston and after assembling it started acting like that ... saw this thread with the same problem so I`m curious did Beasley sorted it out...cheers
.05mm piston to cylinder is the correct clearance. If you've got carbon on one valve, and no others, you either have a bad stem seal, or the valve stem or guide are worn to the point it's allowing the valve to rock enough to allow the stem seal to leak. It is possible (and somewhat common) to damage valve stem seals when installing them over used valves. The stem tips eventually develop a sharp edge or burr from use. This tends to cut stem seals (and scratch up valve guides) when installing.
If the rings were bad, you'd have carbon on both exhaust valves, and it would smoke all the time
the bike was fine , I checked valves and it was out of spec , too much clearence , put it to the spec and assemble the engine and after that it started smoking and spitting
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