The usual smoking question

[Nuggets]

Not to bore yall with another one of these questions but Im at a dilemma. Bike was burning oil pretty bad awhile back. So replaced the piston rings and valve seals. Smoking has decreased greatly but it still seems to do it after about 15 mins of riding and when Im at a redlight for a few seconds. It isnt alot and when I get back up to speed it stops again. No idea what else to do. Ive been rebuilding car engines all my life so Im wondering if there is something Im missing in this engine. 82 GS850g. Pods, jets 2 sizes up (if it matters).

[Guest]

How long ago did you do the rebuild? you state it starts smoking after about 15 minutes of riding , and when you get back to speed it stops.How much oil was it burning before the rebuild and for how long did you run it like that? It sounds to me like your exhaust has oil built up in it and when it gets hot after running about 15 minutes , or gets hotter sitting at a light , then cools as you are riding down the road. Take it out for a good 4-5 hour ride and burn the pipes out good and see if that helps. I have a bike here that has that problem.

[rustybronco]

Like a car, your bike uses valve stem seals also.

[Guest]

Like a car, your bike uses valve stem seals also.

He stated he already did rings and valve seals

[rustybronco]

Sorry didn't catch that he had done the stem seals.

He could have damaged them upon installation.

To the OP...
Did you measure the valve stems and the stem to guide clearance? Piston diameter, cylinder diameter and taper?

[Nessism]

Trust you honed the cylinders before installing new rings?

[tkent02]

Could be a stem seal fell off, just riding loose on the stem now.

[Nuggets]

re

I forgot to mention that its only cylinder #1. Its always only been just that cylinder that smokes. (however I did replace everything for every cylinder). And it is burning oil cause I can see it on the plug. I did do a very light honing before hand. And the rebuild was quite recently.

[Guest]

What did you find wrong the first time? broken ring? bad valve seal? worn rings? , cracked piston? there was something causing it the first time, and if you did not find the problem than that is probably the same problem. When you reringed you staggered all the ends of the rings right? if you lined them up that will cause blow by. Have you done a compression check ?, make sure you do it hot.

[Nuggets]

re

I bought it from the previous owner smoking. . . .

[Guest]

Is it the stock bore or a bigger bore piston did you check the cylinder for being out of round. Any chance you installed a ring upside down? What grit hone did you use to hone it?

[Nuggets]

re

Stock bore, dont remember the size of the hone, but it was very light because the cross thatching was still very very clear. I originally thought it was the valve seals because there was oil on top of the intake valve. I replaced them and still the same thing. Im thinking Ill just take it for a few hours ride and see if the rings will form right. Because since replacing the rings and seals Ive never been on it for more than 30 mins. And yes the rings were installed the right way up. I took great measure to make sure I found the marks on them. (yes and made sure they dont line up with each other)

[Nessism]

"Very light hone" job doesn't get it done. Not sure if this applies, but new rings need an even and uniform hone job with a 240-320 grit dingo-ball hone. Flat bar hones are good for new cylinders, not used. During break in, you need to use the throttle liberally to push the rings into the cylinder wall and seat them. Without surface roughness the rings won't seat.

[Nuggets]

re

Ok well lets by hypothetical for a second. Lets say that each piston got the exact same hone job, same ring job, and same valve seal job. So why is it that cylinder #1 is still the only one that smokes at all?

[tkent02]

Because it was the one smoking before, and you didn't fix the problem.