Ring Seating

I have a 79 kz 1000 ltd, just went through motor, valves adjusted, new rings, fresh hone, all spec out to manual, anyhow, not getting good compression, around 100 on all four, and when i dump, oil into it, I get 120 across all, well compression go up as rings seat? or is this the best i can expect.

Havent started motor yet, and that 100 is with carbs off.

Just a few things come to mind......

Did you gap pistion rings to the cyclinder.

Did you stagger piston ring gaps thoughout the cyclinder.

Is the cam timing correct...if not compression will leak out valves.

Did you adjust the valve clearance correctly and recheck.

yeah, all the above, staggered rings, checked gap, checked piston in bore via feeler guage, all that checked out, also adjusted valves to within .004 on all cyl, did leakdown not leaking at valves, so must be bottom end.

Put some miles on the motor and recheck.
How did you clean the bores before putting motor together?

wireman wrote: Put some miles on the motor and recheck.

The rings have to bed into the bore, that's where the cross-hatch pattern on the honing comes into play. Give it about 20 miles or so and I'm sure it will improve.
RegardZ

I had to do some ex valve guide repair on my Gpz about a year ago, and I decided it would be smart to re-ring while the head was off. My mechanic commented I will need about a good 1500 miles for the rings to seal. He was right, I burned a lot of oil the first 700 miles or so, and now i'm up around 1200 miles, and the oil burning is definately lessening.

Polar_Bus wrote: I had to do some ex valve guide repair on my Gpz about a year ago, and I decided it would be smart to re-ring while the head was off. My mechanic commented I will need about a good 1500 miles for the rings to seal. He was right, I burned a lot of oil the first 700 miles or so, and now i'm up around 1200 miles, and the oil burning is definately lessening.

:whistle: That's not good.

RE: smokey engine - Had the same problem many years ago when I thought it would be smart to let someone else do the bore and fit new rings, the bike would smoke under power and basically the compression was crap. Took me a while to work out that the oil scrapper rings (the second from the top, not the oil expander rings) were upside down. If you check the second ring it has a small taper and must be the correct way up to work correctly.

If this is your case, re hone and put new rings in, when I found the problem I thought just turning the rings would be ok, it never was, just used oil and the power was down. Hope this helps.

lemo32 wrote: yeah, all the above, staggered rings, checked gap, checked piston in bore via feeler guage, all that checked out, also adjusted valves to within .004 on all cyl, did leakdown not leaking at valves, so must be bottom end.

Did you do a Valve job? Or head work of some kind?
The Leak Down Test you did, was it with gauges? If so what percentage Held out of 100 psi input?
While compression should come up with rings seating, it sounds as though you are low anyway. Did you check it with a second compression gauge, as its possible to have one read low. Are you far above sea level, as this will effect readings?

You add oil to the cylinders and the compression only increases by 20 psi? Then your rings are doing an excellent job of sealing, if they weren't then you would have a large increase in psi after adding oil. I've seen over 100 psi increase on worn out rings.

Valves, cam timing, or something else in the head.