Topic: Blowing smoke

[kabuki]

I've got a recently aqcuired 550 motor that sat for about 10 years. It was not seized when I got it, and it had spark and decent compression (~140 psi in all 4). The carbs were full of jello, so I cleaned them all up, and it fired right up. The only problem now is that it blows an unholy amount of white/grey smoke once it's warm. Not noticeable at all at initial startup, just once things are all warmed up.

I'm trying to determine if this might be valve seals or rings (or both) before I tear into everything.

Any ideas?

Thanks,

[TwoTired]

Do the deposits in the exhaust feel oily/slimy or dry?

Have the carbs been vacuum synced?
Are all the head pipes equally hot (about)?

Has it been given the tune up check list?

[scottly]

How long have you run the bike? Have you actually ridden it long enough to really warm it up and burn out any condensed moisture in the pipes? 

[kabuki]

I've been trying to get it tuned, and it is running pretty good now.

One of the carbs was not 100% on the pilot circuit I think, cause it wasn't running on all cylinders at idle. I re-dipped everything and they seem to fire at all RPM now. The carbs are all synched, and now the pipes heat up equally.

The plugs look a bit rich, a lot of soot on the threads and electrode, but tan/white ceramic.

All in all, it's only been run for 10-20 minutes above idle. The smoke is certainly less now, but still a lot more than I'd like. Also smells to me like burnt oil, so that's what I suspect...

[scottly]

Since your compression is good, and the smoke is less the more you run it, I would continue to run the bike. It may get better with time.

[bistromath]

First guess is valve seals, but it's hard to make a really definitive diagnosis. Run the poop out of it on the street for a while and see if it gets better. Could also be a frozen oil scraper ring, maybe. If it doesn't get better, valve seals aren't hard to do on that bike. If the valve guides are good, you can do it without removing the head.

[MCRider]

Since your compression is good, and the smoke is less the more you run it, I would continue to run the bike. It may get better with time.

I agree, nothing lost. My garden tractor smoked like a sun of a gun after winter storage. Put a dose of SeaFoam in it (in the oil) and it stopped within minutes.  Hasn't smoked since.

Stuck ring I think.

[scottly]

Bad valve-stem seals tend to cause smoking when the motor is first started, or when the throttle is opened right after compression braking:the high vacuum generated during braking allows more oil to be sucked in past the seals. I don't think this is the problem here. 

[kabuki]

Thanks,

I'll try the compression braking/throttle check, and then maybe add some seafoam. Failing that, I'll run it for a while and then see where that gets me.

Thanks all.