Uneven compression

HI,

Done a compresion test on my GPZ1100 yesterday.

#1: 110
#2: 90
#3: 105
#4: 125

Wasn't suprise of these result since it was actualy burning a little oil (little blue smoke from exhaust)

I've add some oil in the cylinder and PSI increase of 20 at each cylinder. Look like a ring job.

My question is. Since the bike seem to run well, is it dangerous for the engine to run like this for this summer or I should avoid running with it.

Tks,
Joce

If you did the compression test properly (wide open throttle) then a 20 psi increase after adding oil would indicate that a valve adjustment is needed, not rings.

50 psi or greater increase would indicate a ring sealing problem.

I recently did a compression check on the KZ750E I bought, compression read 85 - 100 psi across four cylinders, a single shot of oil from a squirt can increased the psi by 100 or more in all cylinders. That's bad rings

Thansk for the infos. In the claymer book it say significant increase. I tought 20% was significant.

Glad to hear it gonna be the valve.

Same question, can I run the summer in this condition.

The blue smoke send the bug away when I'm doing a barbecue ;o)

Worn valve seals can cause exhaust smoking especially when first cranking a cold engine (after the oil in cam area has seeped down through the seals). Often see far less smoke after running for a few minutes.

Has someone already recommended checking valve clearances and adjusting as needed? This to hopefully help resolve any compression issues.

Thanks for your advise. I will check the valve clearance and seat valve.

But I would like this to be my next winter project.

Can I run with the bike without damaging the motor?

It was said that valve stem oil seals can cause smokiing. Also, worn valve guides will also cause smoking. The valve clearance checks are part of basic routine maintenance. Most folks wouldn't consider it a "winter project". Can you put it off? You can put off anything; checking the air in your tires, making sure there is engine oil... that can be put off but I doubt I would recommend that bit of routine maintenance either.

This will be my week-end project then...

Thanks,
Joce

See the Valve Clearances article under "wg's Tech Stuff Index" on our website. Might be useful. The GPz's valve clearance check and shim replacement is pretty similar to that of the earlier 903/1015cc engine series, I think.

is'nt it bad for the shim to be riding against the cam lobe all the time, like it induces more wear.

i hope for your sake its shim on top buckets, (81-82) i think if its (83-84) its shim on bottom and you have to remove the cams to shim it.

..........

I'm check the valve on both of my bike:

- 1982 GPz1100 B2
- 1984 Z1100R

Does the shim are in top of the bucket for these two model?

Tks,
Joce

You really need to do a "Percentage Leak Test" and find a friend with a SNAP ON compresion guage.

The PLT will tell yo exactly whats going on, it is a better wear indicator than a compression guage.

Thanks for the advice.

For person like me who didn't know what is a leak test, check the following link:

www.motorcycleproject.com/motorcycle/text/leakdown.html