#4 Smokin! not a good smokin either!

I sure could use some experienced help or ideas here. I have just finished rebuilding my 900, rode it for a short while (about 6 hours total ,no speedo, just a tach). Motor got a Valve job with new seals, guides were fine. It has stock 70mm/1015 pistons in it from a while back. New rings and honing, rings were end gap checked (all ok). I did screw up one of the oil scraper ring sets when installing the pistons the first time, so I installed the best of the old ones I had on that piston, #1.Started it up last Sunday, rode 15 minutes and it started some serious smoking after it was warmed up. I'm talking big clouds here. So, it looks like #4 is the problem, plug is wet and oil fouled. Other plugs look perfect.

Took it all apart this weekend, I figured on a blown head gasket or valve seal, but when I got it apart, everything looked good. There was a substantial amount of oil in the cylinder, and there was a lot of gummy build up in the exhaust port for #4, so I dis-assembled that valve, cleaned it all out, lapped the valve and re-installed. Seal was in new condition, worked fine. Guide also nice and tight, no wobble. I did not check the intake valve, probably should have, but it looked really clean in the port.
As I was installing the head, I realized that the locating pin next to #4 was not installed the first time. Found it and installed it, with a new one piece head gasket, silicone in the center section, etc.. I expected that that must be the problem. Made sense...
I re-honed the cylinders just a bit, and put it all back together. Started on the first push of the starter button.
But, once it was warm, it still smokes, a lot. Essentaily, no change to the situation. Compression across 1-4 is 120/100/110/130 (#4 might be high/normal due to the oil, so I know that there is a bigger problem somewhere.
One thing that happened from the first assembly is that I went a few hours before re-torquing the head, which by then was pretty loose, say in the 10# range. I am torquing the head to 29#, as in the KZ1000 specs.
My plans are to do a leak-down test, then take it down again, and check the head for warp, pull out the intake valve and check that too.
Man, I am getting tired of buying gaskets!
Any thoughts or ideas?
Thanks guys!
K

Are you sure it was the #1, and not the #4 oil scrapper ring that you used and old one of?

That would be my suggestion for checking first, and would make perfect sense if the exhaust valve became that gummed up.
Of course you just might have warped the head near the #4 cylinder due to running it so long before re-torquing the head bolts, but not likely.

yeah, I specifically remember it being #1 cause i wanted to be sure i checked compression there..still, putting in the rings the first time was a little wanky.
k

BTW, there was smoke coming from both the exhaust (most of it) and from the breather...breather was very oily, and is a remote (just behind the Left side cover) K&N type that uses the low profile APE breather
And, though I will check again, valve clearances were all right on, since it has a new valve job, the valve stems were decked to the correct height, re-shimmed, etc.
I am also going to check for fuel intrusion in the oil..
(you can tell I've been reading the older posts...)
K

Post edited by: auggiedog, at: 2007/08/27 14:40

No chance you might have broken a ring when putting it together at some point?
If you're careful you can reuse head gaskets. I haven't tried on a larger Z but on my 750 I could happily reuse head gaskets by cleaning them up good the giving them a coat of metallic paint just prior to fitting them. Only really works on MLS types.

I don't think so, I just had it apart to try and find this problem, so i was able to take the rings off and check them over. I even noticed on Jeff's Z1 ent. website (where i got the rings) to be careful about overlapping the corrugated oil scraper, which was in there ok.
It seems like oil is getting in from the top, not sure why I think this.
The burning/smoke is heaviest under load...
you know though, the middle ring was clearly marked with the "N" for up, easy anyhow bc of the chamfer, but the top ring had no marking, and no matter how close i looked it seemed the same either way. I did my best guess to get a chamfer down on the top rings.
Might be able to re-use this new head gasket, thought I might givie it a try since I am getting so good at taking this #*%@ thing apart! :S

I had the same problem. Mine was a broken oil ring. could it be you missed fitting one of the valve stem seals or didn't snug it down?

The fact that its smoking under load normally indicates a ring, piston or cylinder problem.

Also try removing any filters or whatnot from the breather. Just run it to open air for an experiment. My bike is incredibly sensitive to any restriction in the crankcase breather, Smokes badly. I currently have it venting to open air via a 30" hose exiting near the tail light, which lets any oil run back down into the crankcase should it get that far up.

It doesn't sound like a valve seal. Bad ones normally cause trouble on the overrun or when the throttle is closed. The vacuum in the inlet causes oil to be drawn down past the valve into the cylinder.

sounds like ring problems to me, did you install them dry?.
also you can pull the schrader valve out of the compression gauge and put air to it, you will see where the problem is real quick

it's possible that the intake seal is not on right, i did not check that one. I remember reading about your broken ring...
I actually had it apart and check the rings off the bike, they all looked really good.
I think I should just take it apart and go over every thing again..

this breather thing might be it...one of the things different is the new APE low profile breather cover. I installed it by removing the two rubber "vents" inside of the original, taller cover, as well as the plate that held them in place. New APE Cover then fit correctly.
I added about a 16" vent hose to just behind the side cover, and then terminated it with a crankcase filter, looks a lot like my pods on the carbs.
There has been a lot of oil on the filter itself..
I'll try removing the filter first and see what I get.
Another thing is that the cylinders are newly honed, so the rings might not be seated fully yet, hence the lower psi readings..might be a combination of factors....
Thanks!

if I am reading this right and you are getting a fair amount of oil in your crankcase breather filter then I would have to say that it is more then likely a ring...blow-by is caused by compression slipping by the rings and into the case causing too much pressure in there hence the blow by