'81 GPZ550 Oil Seeping at Barrels / Block Joint

Piston rings can and do migrate.
Steve

I can't say if it's true or false, but here's an interesting article. Ed

www.diagnosticengineers.org/journal_%20a...Knowledge%20Gaps.php

Piston rings do rotate on the pistons, at varying rates. After a time they can take a set in one position on the piston. There are differing reasons as to the importance of setting ring gaps on initial start-up, such as maximizing cylinder pressure on that first start and in some cases, just giving the engine builder some peace of mind. Sometimes the importance of setting ring gaps seems to be overstated, since the rings tend to rotate, however it is probably very wise to follow the factory recommended positioning of ring gaps. I re-used the old rings on my 42,000 mile gpz550 following head and base gasket replacement and have not noticed any difference in performance. Obviously, this is a highly debatable topic with no particular right or wrong answer. If in doubt when tearing your engine down, install new rings and hone the cylinder bores, while following the factory stated ring gap position.

DGA wrote: No, a 2 stroke's rings are pinned so they get installed in the right place, how else would you get the gaps exactly in the right place?...

I think it's so they don't end up in the wrong place....the cylinder intake and exhaust ports ...and get snapped off.

As stated before, the bores have to be true. If there is a ridge, chances are the bores are worn beyond service limits and or out of round. It is possable to "size" the bores by using a feeler gauge at the top, middle and bottom. If still within limits, I would use a block hone and new rings. I've heard of oversized rings being used but I haven't done it myself. If the bore is at the limit, the rings will be stressed that much more and can "walk around."


I set my rings as called for by the instructions. One more thing to take pics of while I install my Wiseco 10.25/1's.
Will be interesting to see how far they have moved in the last year and a half.
Steve

I won't comment on the ring thing, but the leaks are the standard Kawasaki oring rubber hardening and leaking. Why the use orings all over is beyond me, but it didn't work. Unfortunately to replace orings, the gaskets need to be replaced as well. Re torque of bolts won't fix a hardened oring

Glad I don't have them in my Z1. The big one is enough for me. Got rid of that puppy. :evil:
Steve

650ed wrote: I can't say if it's true or false, but here's an interesting article. Ed

www.diagnosticengineers.org/journal_%20a...Knowledge%20Gaps.php

Interesting article, but I don't see how a ring can produce a "tangential load" when it exerts force against the cylinder wall. Doen's he mean "radial load"? If the ring is pressing against the wall, the force vector is radial relative to the piston axis.

What causes the rings to rotate I think is the tangential load of the rings against the cross hatch hone pattern, like a bullet spinning out of a rifled barrel. The radial force is the combustion pressure pushing the rings hard against the bores. Some rings don't seem to rotate that much, although they are supposed to...7 rpm is the figure I've seen.

For a less than 1 minute task, setting the ring gaps just seems like good practice, if they rotate then little time wasted, but by staggering the gaps, if the rings are sticky it will minimise pressure loss through the ring gaps...that's the theory anyway. Also those first minutes of running time is critical for break in-which requires a strong radial force on the rings to bed them, gapping the rings evenly will maximise this.