I'm new to this so please forgive me if this has already been discussed somewhere. I have a 1991 Heritage softail that is essentially stock, but has an Andrews cam (Can't remember which one), The bike has about 14,000 miles as it sat for many years. I started riding again about 6 months ago and it ran good, but I had a Intake manifold leak and a base gasket in the rear cylinder leak. I got a wild hair up my *** one day and took both heads, cylinders off and replaced all the gaskets. i didn't do a compression test beforehand. After all is said and done, I put everything back together and started it today. I ran pretty darn good. As it warmed tho, I started noticing white smoke come from the engine and out the tail pipes, The rear cylinder has more smoke then the front. I didn't replace the piston rings or take the valves out of the head while it was apart. The white smoke concerns me as it never did that before. After reading several threads, I did a compression test and the front cylinder was 155 PSI, then with some oil about 160 PSI. The rear was about 150 PSI, then 160 PSI with oil. How do I read these results? Does the white smoke tell me to replace the rings, valves, or is it normal to have white smoke for a while after a top end rebuild?

 

technically you did not rebuild it.
how heavy is the smoke? it could be normal depending upon ambient.
could be a head gasket leak. white is usually unburned fuel or fuel that did not combust properly, normal combustion does produce water vapor also.
run it awhile and see if the rings seat back in, did you deglaze the cyl?
does it go away after it warms up? even mine if i run it hard will huff some white smoke if i do not go through a cool down.
since it is not water cooled, no issues there.
what about the umbrella valves in the heads? replaced? functioning?

 

I don't believe my year came with umbrella valves. I looked them up and I don't have anything like that in the heads. The smoke on the rear cylinder is fairly prominent coming from the tail pipe. The smoke from the front cylinder is less from the tailpipe but there is some from the cylinder head area itself. I can't tell exactly where its coming from. I did not deglaze my pistons. Basically, I went in there and cleaned everything up , put a light coat of oil on the cylinder walls then put it back together with new gaskets. I followed the manual to a T. A few minutes after I started the bike, I noticed that my front exhaust pushrod was leaking oil and it was dripping on my front exhaust pipe. This caused a lot of white smoke. I fixed that. There isn't any smoke when it first starts. Once it gets warm (Or probably HOT), the smoke starts. Thanks for tying to help me. I really appreciate it. I love to work on the bike, but I am definitely a beginner.

 

Ride it for a tank too see if your rings reseat. You should of run a hone in the holes to help the rings reseat after separating the rings and the bores.

 

After running again today, I believe it is more of a blue smoke coming out of the tailpipes. This would mean I was leaking some oil, right? I have let it idle for about 45 minutes today. At first there was no sign at all of smoke (for about the first 15 to 20 minutes). Then it began to smoke a little, then more. It is clearly noticeable now. as long as I am not doing any permanent damage, I'm gonna try to ride it for a while to seat those rings. But, could it be the valves also? Thanks again

 

Letting an air cooled motor idle for 45 minutes is not good, you will over heat it; which you may have done. Blue smoke indicated burning oil. Check oil level and see how it runs after cooling off.

 

Broken/distorted ring, upon re-install?
Valve seal harmed?
Scott

 

put it back together with the old rings?ill guarantee that's your problem

 

 

The 45 min idle time, could have also removed the ring tension, via overheating, and/or smeared a piston skirt.
Scott