I've recently done a top end seal job on my 2000 bike due to excessive oil usage and blue exhaust smoke. Replaced piston rings, cylinder base gasket, head gasket and O-rings and valve stem seals.

This seems to have cured the blue smoke but after re-assembly I have developed a new issue. On idle the exhaust is giving out white smoke, this continues when the bike is warmed up and off the choke. Putting a piece of paper over the exhaust and revving the bike produces no significant black marks and doing the same with my hand yields no oily substance. I'm thinking the bike is running rich on idle. The spark plugs are sooty and dry but not oily.

While I had the bike apart I took the chance to locate the pilot screws and see what they were set at. The left cylinder was 2 turns out and the right cylinder was 2.5 turns. Looking on the forum people recommended setting these both at 2.5 and adjusting from there. So after a few hours of fiddling with the screws I can't seem to get rid of this smoke.

Any advice on what else the issue could be is appreciated. And, if it's any help both carbs are pulling about 220mm/Hg on idle.

Adjust the carbs correctly: warm the bike completely by riding it on the road for 15-20 minutes, then set the idle speed to about 1200 rpm and turn the pilot mixture screw on one carb out a quarter turn. If the idle speed increases, turn it out another quarter turn, etc. until it stops increasing in idle speed. If the idle speed decreases, then turn it in 1/4 turn at a time until it stops increasing, and then turn it back out 1/4 turn. Repeat for the other carb.

You can't just assume "2.5 turns out" works. You have to actually adjust it.

FWIW, rich will produce more black smoke. "White" smoke usually indicates water. Could there be condensation in the tank or the carbs causing water to get in the fuel? Otherwise it might still be oil.

But hey, my bike also blows some light gray/white smoke when I first start it cold while it's warming up, and it has only about 3-4K since top end rebuild and definitely isn't burning significant amounts of oil, and the mixture is dead on. So this might just be normal.

I'm sure it's not water in the fuel. The bike has been apart for a couple of weeks and the fuel that was in the tank was drained and has been in a couple of fuel cans.

I didn't set at 2.5 turns out and leave them there. I've been trying to adjust them with a similar procedure to what you stated but people stated that 2.5 turns was a good starting point.

I'm gonna take it out tomorrow and get it good and warmed up and try again. Also try some fresh fuel in it because.... may as well.

Mine smokes on choke when I start it up,... Smells,...terrible in a closed garage

Random .02¢ comment,..

Sounds like a plan to me. Mine always does this white smoke thing a bit on cold start, who knows why. I still guess condensation causes some water to get into the carbs. There's air in there, that air has moisture in it and a dew point, it will condense water droplets once the dew point is reached, and there's nowhere for that water to go but inside the float bowls, and mix with the gas that's going into the engine. Again, just a theory.

EDIT: The Internet reveals another good theory. If gasoline combustion is complete, the result is water vapor and CO2. When the air is cold, in the exhaust pipe, for example, that water vapor can condense and come out as a visible steam rather than invisible vapor. Once the exhaust heats up enough to keep it from condensing, you don't see it anymore.

So I like the Internet's theory better than mine.

ANOTHER EDIT: Oh, and while the choke is on, there may be a substantial amount of unburnt fuel in the exhaust as well and it may be cooled enough to be droplets and not vapor when the bike has not been run. And this may be why you perceive the condensate as "oily".

I'll stop editing now, maybe. Have fun.

Noooo, I said the vapour was not oily. That's why I think it's fuel rather than oil. The plan still stands. Take it out for a good romp tomorrow, fresh fuel and re-adjust carbs.

not oily == definitely water vapor. you pick your reason for why it's there, but it is what most of exhaust is made of.

Quote from: Oscar_Muffin on January 29, 2020, 10:57:52 AM
This continues when the bike is warmed up and off the choke.

For most vehicles, white smoke after warming up is a coolant leak. That can't happen with a GS500 since there is no coolant.

I just can't imagine there could ever been enough fuel left after combustion to create a visible smoke. When you say "warmed up" are you saying that if you drive around for a full 15 - 30 minutes with the choke off there is still white smoke coming out of the exhaust? A GS500 takes a long time to warm up and for water vapor to stop condensing in the exhaust. Especially in the winter. Just because the bike runs without choke does not mean its fully warmed up.

Water is inside the exhaust pipes. Condenses when they cool. Mine blows out the back with a smaller amount out the weep hole at bottom front of muffler

Mine does the same as cbrfxr67, until it calmed down a bit after getting going its a bit skanky.