Valve clearance

Hi

I checked valve clearance today did not quite make specs. 3 of the valves are .07mm clearance and not in spec range of .08mm to .18mm. I have had low compression problems and this was one things I have not checked.

Should I go ahead and change the shims? Is it possible to move some shims around so to make all valves in line with specs?

Thanks
Ray:woohoo:

if those 3 valves are only .01mm tight that should not have much effect on your compression numberrs.what are you getting for numbers by the way and are you checking them with the throttle open or closed.

Wide open on compression test. I have started to see a increase in cylinders 3 and 4 but both are low. Cylinders 1 and 2 have always been higher but have started to go down. I have re-torqued cams and heads. I have also stripped out the spark plug threads in cylinder 3 ;so that has me concerned.

I have tried everything that I can to fix short of complete tear down. I need to try another compression test but if I have low compression I might just pull top end and take a look.The numbers below is what I remember.

cyl 1 120psi
cyl 2 115psi
cyl 3 45psi
cyl 4 90psi

Thanks
Ray

45 psi would indicate a major issue - probably a bent valve or a major issue with pistons/rings.

Usually with a bent valve, you have valve clearance extremely wide (as the valve is not returning fully.

I've never had that low a compression with worn rings, so you may want to go back through and verify the numbers. If you have a leakdown tester, they help tremendously in isolating the issue.

i agree 100 percent with what jeff said it sounds to me like you could have a collapsed ring land or the rings have siezed in the ring grooves somehow usally by being overheated or lack of lubrication

... all been said...

Re-Build the top end

You will re-LOVE your bike! :laugh:

Good luck!

".08mm to .18mm"....

Which bike is this for?

Spec on KZ900 for sure, 1000 I think is .05-.10mm....

1980 KZ750E 4 cylinder.

Old Man Rock wrote:

".08mm to .18mm"....

Which bike is this for?

Spec on KZ900 for sure, 1000 I think is .05-.10mm....

My 1000 is .05 - .15mm

Latest compression test. I get cyl#1 115psi,cyl#2 100psi,cyl#3 90psi,cyl#4 92psi. I think its time to open it up and take a look.


Thanks
Ray

Stripped spark plug threads will adversely effect your compression readings. I happen to have a repair kit on my shelf just for that problem.

IMHO, add some oil to each cylinder and re-test. If it’s about the same then it probably valve related. If it shoots way up, then it is probably ring/piston/cylinder related.

Best of success.
Bill