smoke from crankcase vents

[roselenore]

Have put about 50 to 75 miles on a fresh top end of a '79. Did not replace rings and never took the pistons out of the sleeves. Bike had 17,000 miles but sleeves looked very good. I'm running pod filters with Mike's XS filters on the ends of the crankcase vent tubes.

Problem is I'm getting a fair amount of smoke out of the crankcase vents. Does this mean rings, or could it be something else?

 

[Valkyrie]

yes sounds like blow bye

 

[scabber]

A leak down test should tell you if you need rings. Did you check the compression before the top end. Put some more miles on it check oil it might clear up. If it is just smoke and not blowing out oil it might be ok.

 

[roselenore]

Did not check the compression (dumbass) guess I should have. As I said, the cylinder walls were slick as glass, but in hindsight I should have done the rings while I had it apart. Thanks

 

[Paulrxs650]

If it was OK before you took it apart, there's something not gone back as it was - Did you ensure the ring gaps were all correctly offset?
What else did you do to the top end?

 

[Tomterrific]

"the cylinder walls were slick as glass"

They should have a cross hatch pattern. From a distance, it appears the walls and rings are worn out. Also make sure the carbs are not leaking and washing the walls.

The very cheap pods from mikesxs will not work with stock CV carbs but this is just an old heads up, not a reason.

Tom

 

[jayel]

how cold is it where you are? could you be seeing condensation burn off? any smoke from the exhaust?

 

[dirtymike]

Toms correct, the walls need to have a cross hatch pattern to hold a small bit of oil for lubrication and cooling. The bore is probably not round anymore. Once this starts it will just progress, not at a fast rate but enough to let blow by through the rings. Ive seem them last a long time though. Usually starts to burn oil and builds up carbon on the valves. When the piston skirts start to rub the sides of the bottom of the bore you will get piston slap. This is a sigh the end is near. I've seen these engines run in very bad condition. They seem to keep running though. Just something ive notice working these 360 plants. Dirty

 

[5twins]

How much oil is in it? It's recommended to run the oil level halfway between the low and high mark on the dip stick. Filling it all the way to the high mark may be too much and that excess can blow out the breather.

 

[roselenore]

Did not remove the pistons from the cylinders so I never looked at the ring gaps. Mainly just cleaned the heads, lapped the valve seats, and new gaskets, o-rings, and sleeves.

 

[roselenore]

I did say "slick as glass", mainly I meant there were no ridges in the sleeves.

I am running the cheap (Mikes) pods with re-jetted stock CV carbs. What's that doing to me?

 

[roselenore]

The temp was in the 60's and the engine was good and hot when I saw this. No noticeable amt. of smoke from the exhaust.

 

[roselenore]

Wonder if all the cleaning I did is allowing oil to get by.

 

[roselenore]

I wondered about the oil level. I filled it slam full before I started breaking it in. I'll let some out.