It begins! things have been going quite well with my 600ss, though it has lately taken to fouling spark plugs on the horizontal cylinder, I had assumed it was too cold a plug, I went up a heat grade of plug and problem solved! Except it isn’t! The bike now produces a faint puff of smoke from the exhaust when one blips the throttle and there is a considerable amount of oil residue in the exhaust. The bike has done 26k miles and starts on the button, I left the country for 6 weeks for work and on my return it fired straight back up again. I had the bike dyno’d on Tuesday and it was showing 44HP at the rear wheel, so I’m praying that it isn’t piston rings. What do you think? Leaking oil stem seal?
Leaking valve stem seal usually smokes on start up, not on blipping the throttle - I would be looking at the oil control rings.
Check the valves (especially the exhaust) for play/movement within the guides. I recently had my 900 engine apart for gearbox work and was shocked at how worn the exhaust valve guides were after only 15k miles. The intakes were pretty good but the exhausts were flapping about something silly (they get a harder life due to heat buildup). It wasn't even particularly smoking or burning oil but wouldn't have been long before something went bang.
The exhaust valve guides are a recognised weak point on these engines. Dunno if it was remedied for the injection motors. My carbu 900 had paperwork from Baines racing stating "worn guides" at 6k miles...
