1980 KZ750 E Cold pipe, no compression, opening valve cover

Long history, now my divorce survivor bike.  Broken air fuel needle found in carbs. Blasted air, rebuilt, cold pipe.

Rebuild down to fresh base gasket, all new seals, valves machined, re-shimmed, new carb o-rings after cigarette test, kwik tuned by oldskooler.   Cold pipe.

Replaced the carb body in the rack.  Same cold pipe.

At shop, re-cleaned and checked carbs, cold pipe.  No compression in that cyl but I swear it had comp on rebuild.  

Opening the valve cover, my manual didn't survive the divorce. I'm hoping some of the oldskool crew are still here. Nessim, so many others, I'm back!

Clint

I assume you have checked with a compression gauge, have you done a leakage test to see where the compression is going ?

No leak test.  Is there a chemical and UV light type of test? 

I just measured the valve clearances. All are in spec EXCEPT the Intake of Valve 2, the cold pipe, measuring 0.43mm with a FSM range of 0.08-0.18mm.  

I'd like to replace the shim and see before taking the valve body off.  All the cylinders and rings were spec, fresh gasket and seal the whole way.

Also, at 1-4 T top TDC at ignition the camshafts seem off by 1 tooth, with Z7EX just angled above the valve body.  I can't move them both 1 tooth as they align with the chain links properly.  Could it be off by 1 link at the bottom?

Thoughts on leak?

That clearance of 0.43mm would seem to indicate that the valve is either bent, or, something is stuck in between the head of the valve and it's seat, preventing it from closing.
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The cylinder head will have to come off I'm afraid...

H.

A leak test would confirm that, the chemical test I think you are referring to is for water cooled motors and detects hydro-carbons in the fumes above the coolant in the header tank (this is a test for head gasket failure rather than compression issues)

ASAP - OEM Kawasaki Shims VS 4140 Cold Rolled Steel
z1parts.net/13mm-valve-shim-kit-4pcs-of-...n-0-05mm-increments/

ISO shims posted, 13mm diameter, 2.6mm-3.1mm

It could just be sloppy work at the machine shop, or something seating better.  I can see how debris down there would cause a little lift and gap, but I would think there would be some mechanical feeling or resistance as I turn the 17mm driveshaft nut. Hmmm...

Cylinder likely never fired. Checking leakdown, then pressing valve out to check it.  Totally makes sense that if it was off by 0.2-0.3mm it would not prevent the valve from opening; would just be a slappy loud valve. wrote: That clearance of 0.43mm would seem to indicate that the valve is either bent, or, something is stuck in between the head of the valve and it's seat, preventing it from closing.
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The cylinder head will have to come off I'm afraid...

H.

Wow, that one cylinder hasn't seen ANY combustion at all. since re-build !!!

 

Opening the valve cover, my manual didn't survive the divorce. 

not sure what that means. but the 750turbo site has a good manual. the one here on kzr is a crummy version but that would be better than nothing.

Today I drained all 4 carbs after prime and got just under 50cc except the rightmost sitting on bike at 55cc, meaning everything is good there or the one is overfilling and fills the cold pipe bowl from the common fuel rail... I think it is good, any need to adjust that last float to make sure and do it again?

Pic 1: kwik carb holder setup w string.
Pic 2: butterfly look really close to same, this was after rebuildi g the carbs with a new body for pipe 2 from left.

I have not done further leakdown using the air method.  Following another thread with the same issue.

This looks like the same thing that happened to me on my '82 KZ750 top end rebuild.

The main culprit was a malfunctioning cam chain tensioner, that big ugly double wedge job. I bent two valves because the cam chain had slop in it when first fired. No compression in one cylinder, one intake valve bent .002" and one exhaust valve bent .004" both straightened on lathe then reground.

Did you replace the cam chain with a new one?
If you don't then the cams will never line up at TDC like the manual shows, always up or down from the gasket surface. I ended up setting my cams up by using a dial indicator on the tappet to tell me when the valves were closed! I have since ditched the giant auto tensioner for a manual unit.

This spring I am going to slot my cam sprockets so I can better set the cams up, this is one way around a slightly elongated chain (the chain was within FSM limits)

*SOLVED* Bent intake valve.  The exhaust valve looked fine, I might pull and check it too. I swear I was meticulous on timing chain, but it looked like it was off by ome tooth with the correct number between cams by memory.  I felt like the chain tensioner engaged properly.  The bike rev'd up high upon starting, which may have bent the valve.  It was stuck in the seat a bit, but pushed out by hand.  Newly machined seats and valves from the rebuild.  The shop.did not re-shim or grind the valve ends, so I made them redo it.  Swear they were all str8 on first disassembly...