White Smoke Help Please

Not open for further replies.
Jun 12, 2007
I finally got my inherited 850 back on the road on Sunday. It's been off the road for a few months and I've put on new electrics, new brakes, welded up a cracked exhaust, sorted out the isolastics........

So now on to the next problem. Can anyone help me out as regards finding the solution to some white smoke coming out of the left hand side of the engine? It's particularly bad when I go from Idle and blip the throttle and is perhaps worse when the engine is warm. I've set the tappets, changed over the coils and spark plug but the problem still persists. It also has Boyer electronic ignition. Could it be the carbs not tuned properly?

Any help would be much appreciated.

Hello Matt

As Hehwo has said, white smoke is a sign of oil burning, so could very likely be an inlet valve oil seal problem, or the inlet valve guide could be loose in the head? Or the oil scraper ring could be stuck? A top-end strip is probably the only way to tell for sure.
Before you go whole hog, and pull the head off/apart...check compression, it could, as said, be a bad oil ring, but think you would likely then have smoke on both sides, as both rings would presumably be the same age and wear as the compression rings and you would likely have a real low compression. My bet is not on the rings. Look too at the valve seal and see if it is off, ripped or just plain too old and loose/cracked. If not...loosen also the intake valve rocker and see if you can wiggle the valve and the valve guide. Some have had to Locktite the guide in to stop it sucking oil into the combustion chamber. Mine had a similar cloud, and it only needed to have the seal put back on, sometimes the seal gets cut up too, when putting the retainers on the valve spring if you compress the spring too much. Bet it's something simple and cheap to fix... :D
I had just a touch of white smoke from each side until I replaced the rings this winter.
I think the PO had upped the pistons to +.20 but used the old rings (?!). The gaps were 35thou when they should be 12thou.

As Hewho said - start easy (and cheap), then get fancy. It is a good way to get to know the bike without emptying your wallet.
Not open for further replies.