Snapped Exhaust studs part II

[maxzer1500]

[quote author=Fazerider link=topic=17020.msg196415#msg196415 date=1432139280]
Have a close look at the pistons and rings.
If there are signs of blow-by down the sides of one of them it might explain the state of all of the piston tops… excessive leakage pressurises the crankcases and more oil mist blows out of the breather into the air box.

thanks will take a closer look and get some pics of the insides of the cylinders - i am not sure if there is a mark on one of them!
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    It's probably not worth checking ring gaps and if the oil was spilt removing the head shouldn't be too much to worry about. If it was mine while apart i would be tempted to lightly go over the bores with scotchbrite, would be like a light hone. And replace the valve stem oil seals, pattern probably ok. There was an issue with some Yamahas that came with fully synthetic oil and it didn't do much good for running in purposes with the lead on effect of oil burning. I was lucky with my thou as from using a pint every 1000 miles it now uses nearly nothing, i suspected the previous owner used fully synthetic so just changing to semi seemed to sort it.