Low compression, oil out the breather. kz900/1000

Ok, here's where I'm at.
Intake valve clearance in mm.
Cyl1. .07
Cyl2. .03*
Cyl3. .10*
Cyl4. .08
Exhaust
Cyl1. .14*
Cyl2. .09
Cyl3. .07
Cyl4. .07

*on the edge or out of spec.

I took my compression tester and removed the Schrader valve which allowed me to pump air into the cylinders. I set the regulator on my air compressor to about 5 pounds and opened up the oil fill cap.
With the valves closed cyl 3 was passing air into the crankcase as I could hear it escaping out the oil fill hole.

There was no noticeable smoke from the exhaust when I rode the bike.
I'll have the head off tomorrow, expecting to see a hole in the piston or broken, worn or misinstalled comp rings.

I better LOVE riding this thing when I'm done, lol.

You will.
Steve

Well I stayed up way too late, the head is off.
No major scoring, no obvious answers yet.
Bedtime for me!

Did you do dry compression test?
Wet test would increase compression of bad rings.
Turn head upside down and fill combustion chambers with ATF. You'll see valve leaks after 20 min.
Same test can be done in cylinders if you didn't remove cyl. block yet.
2-5 table spoons of ATF for each cylinder

Fill the intake ports with diesel fuel to check leakage then the exhaust ports. Those are high compression pistons. I suspect 12/1. Can you measure the bores? Pics of the head and bores? May have kissed the valves because the clearance wasn't checked.
Steve

.

Car car was talking about letting atf sit in the chamber of the heads off the bike while it's apart.

I'll post more pictures tonight when I get the cyl block off and get a chance to measure the pistons and look at the rings.

with the head upside down on the bench with the cams removed I filled the chambers with atf before I left for work, I'll have my wife send me a picture in a bit to see if any or all has leaked out past the valves.

Only one of the damn valve shims still had any size marked on it, so I'll need to measure them and do some math.

Got plenty of things to do after work.

Looks like a big bore kit has been installed. I wonder what other goodies are in it?
Steve

I know it has at least 1000 pistons in it because of the kz1000 cylinder block, outside of that I have no idea.
That's one helluva dome on those pistons! (keep in mind this is first kz engine I've ever had apart).

The cams looked like it was in decent shape and didn't look to me to be any crazy hop up parts but I've not measured anything yet.

Also i read you could identify the head year by looking at the cam guide chan holder so I'll attach a pic of it as well.

These are the cast 10.25/1 pistons.


The 1015 billet piston is in the center. Stock is on the right.


Steve

Well here's the problem (or one of them)