blue smoke from right cylinder only at idle?

I have an 850, cylinder head was done last year, a problem arised at the end of the riding season. Where at idle when the engine is hot the right hand cylinder will smoke quite badly, burning oil. If I bring the rpm up over 1800, it will clear itself and I have no visible smoke. Let it idle again and the smoke appears. Anyone have any ideas, my taught was the valve seal worked loose or is damaged, but why only at idle will the issue come up and not be constantly smokin over the whole range of rpm.

I was using syntetic oil last year 20W50, someone suggested that I should use only straight 50 oil and that might be the problem as the 20W50 is too thin. Still doesn't explain only burning at idle though.

Any ideas would be much appreciated.

hiya it sounds like a worn valve guide or seal , at idle there is a lot of suction on the inlet guides when you open the throttle it relieves a lot of the suction just a guess tho

Intake vacuum is highest at idle when the throttle is closed. Oil gets drawn into the combustion chamber around the intake valve stem. The rubber seal has probably come loose.

thanks for the info, that explains why there is smoke on idle and not at speed. I will remove the head and replace the valve seals as this is the easist solution with the tools I have. Hope its not the valve guides.

Exactly the same thing my bike was doing. Smoke was also noticeable on downshifting. I was burning a fair bit of oil, maybe a pint per 300 miles. When I disassembled the head, the valve guide seal was missing on the right side and the right hand combustion chamber was all gunked up and oily. I ended up replacing the valves as the edges were pretty pitted and I also installed the "improved" guide seals from MAP. They are supposed to stay on better than the OEM jobs so I guess we'll see. I am a day or two out from startup!!

Oil could also be going down the outside of the guide due to slightly loose fit in the head. As long as the guide is not flopping around, when you replace the seal you can try degreasing well in that area then goop around the guide and under the valve spring seat with some Yamabond. This is not really fixing the source of the problem but may get you through the riding season.