Oil from exhaust

[DaKyy]

Hi there

I've got a -78 GS750 with a bit over 40000 miles on it. I just got it few weeks ago and noticed it is losing some oil. There are no leaks on it so it must be burning it.

Later I noticed black spots on my garage floor(like from spray can) under the right exhaust (don't know the cylinder numbers...) - the two water drains under the pipe were puffing oil when the bike was running cold. After it gets warm it stops - probably cause oil starts to vaporize aswell.

I don't know anything about the service history - but I bet it has been taken care of because I'm the second owner. I'm not very familliar on the bike engines but first I'd suspect piston rings? Second - I really don't know when the valves has been adjusted. The bike runs well and it starts quite easily - although I have to use choke to get it started. But I'm not an expert as this is my first bike.

The bike has now gone to winter storage so I have no access to it. When the spring comes I should do:

#1. Don't care and just drive and add oil
#2. Adjust the valves
#3. Replace the piston rings
#4. Something other I haven't thought of?

[Graham]

I'd say valve guides and seals. Oil from rings should foul the plugs and smoke. Bad exhaust valve guides just smoke and leak oil.

[bwringer]

The black spots are just dissolved soot from the inside of the exhausts. Condensation is perfectly normal and expected, especially when it gets colder. As the bike warms up, the water turns to steam more quickly and it stops dripping.

Anyway, by the time things got to the point of seeing liquid oil running from your exhausts, you would not be able to see the bike when it's running because of the immense blue clouds of burning oil. You'd also notice a complete lack of mosquitoes in your neighborhood and angry environmentalists at your front door.

As far as oil consumption, how much, and under what circumstances? All engines burn some oil, and a perfectly healthy GS engine will burn some oil as well. New car manufacturers don't consider it a problem unless you're burning more than one quart every 1,000 miles. Oil consumption can also vary dramatically based on RPM and usage -- if you're droning along the highway at 80mph for extended periods, you'll use more oil than putting along back roads.

In sum, just keep an eye on the oil level, worry less, and ride more.

[DaKyy]

Good to hear. It was just odd that the other two cylinders didn't puff oil out at all. I'll just keep an eye for the consumption then

[bwringer]

Catch some of that drippy black stuff on a piece of paper. It should be pretty easy to tell whether it's oil or just soot (carbon) and water.

[Big T]

And, adjust you valves!

Then, after you service it next spring, check compression and oil consumption and post that up here.

Only on the right side? (3+4, BTW)

Was the bike parked on the sidestand for a long time before you bought it?

[Nessism]

And, adjust you valves!

Agree! The valves need to be adjusted, period! Whether or not it fixes the issue at hand is unimportant.

[Redneck]

I say let it smoke so you get the opportunity to knock the teeth out of the angry enviromentalist.... I am just saying is all.