Exhaust Smoke

[Guest]

This one has me a bit nervous. When I was working on the electrical on my bike and reving the motor to check my voltages I noticed that my left exhaust (cylinders 3&4) was smoking pretty bad. I didn't notice the issue on the left side.

I'm already thinking I'm going to have to open up the head now, but I wanted some expert opinions/diagnostic ideas. My guess is rings or valve seals, but that's just a guess at this point. Are there any other things that could cause the smoke. It was a blue/white smoke, not gray/black or sooty.

I do have to add oil often.

[amxsteve]

Do a leak down test first to test cylinder leakage

[MAJikMARCer]

Do a leak down test first to test cylinder leakage

Thanks Steve. I've never heard of that test. I found this YouTube video. It's on a Honda car, but the concepts should be the same right?

[tkent02]

Smoke while revving it up quickly and smoke while going down the road are two different things. Lots of engines smoke during a quick rev, no big deal. Also if the bike has sat idle a long time it will be more likely to smoke a little, if the carbs are not perfect it may smoke a little, it there is a lot of carbon built up it may smoke a little.... The list goes on.

By the way, 3&4 are the right two cylinders.

[MAJikMARCer]

By the way, 3&4 are the right two cylinders.

Jeez...you'd think at my age I'd know my right from my left by now!

The bike had been idle, but my wife had noticed on previous rides that I had been puffing smoke now and again, usually while accelerating.

Sounds like the leak down test would be a good idea though.

[duaneage]

Valve guide seals are probably hardened. Mine were and just starting to cause a problem. They can be replaced without a head off but it's easier if you do and you can solve any leakage issues at the same time.

[koolaid_kid]

"Normally" when the valve seals start to go you will see a small puff of smoke on start up. Look for that after it sits a bit and you go to start it.

[GS650E_81]

Old betty has sort of the same problem. On start up it will throw white smoke out the exhaust for about 30 seconds or so. I am not sure if the seals are bad or just condensation. Don't think condensation is the problem as it sits in the garage year around.

I have never personally seen any smoke come out when I rev at idle. I have seen a few puffs of smoke roll out the right exhaust after starting it up for a minute then shutting it off.

[koolaid_kid]

Old betty has sort of the same problem. On start up it will throw white smoke out the exhaust for about 30 seconds or so. I am not sure if the seals are bad or just condensation. Don't think condensation is the problem as it sits in the garage year around.

I have never personally seen any smoke come out when I rev at idle. I have seen a few puffs of smoke roll out the right exhaust after starting it up for a minute then shutting it off.

While not a show stopper, it does sound like replacing the seals is in your future. Research it thoroughly, it makes for a good winter project if you do it correctly.
How is the bike running, otherwise?

[duaneage]

When I had the head off I could see the first starts of oil deposits building up on the exhaust valves. That's the first sign of leakage.