Motorcycle Repair: piston rings, piston rings, oil rings

Question
hi wayne, i tore my engine apart and i noticed the oil ring on all 4 pistons is flush with the piston and not sticking out at all, is it suppose to ? its the one at the bottom of the piston that is different than the othr 2 on top of it, also the other 2 are still sticking out but i can compress them without much effort. Should all these be replaced then?

Answer
Hi Reid,

The oil rings will not stick out very much from the piston.
When new they may have a little tension but not like the
other compression rings.

If the tension is low they should all be replaced and the
cylinders cross-honed to make a break in surface.

The top and second rings should not be too loose
in the piston grooves either. About .004"
maximum side clearance in the piston grooves.

Put the marks on the ring ends facing up unless they
come with other directions.

When you put the wavy oil ring on let the ends
butt together, do not overlap them.
Once you get the other side oil rings on
it will all straighten out and have more
tension than your old oil rings.

Try to stagger the ring gaps so they do not leak easily.
Have all the ring gaps at different places around the pistons.

Be careful with the new rings as you can not bend them
too far without breaking them.

You can slide the new compression rings
into the cylinder to make sure they will fit.
There should be a gap of no more than .020"
or about a half millimeter on the top and second rings.
The oil rings can have about 1 mm max gap or .040"

Rings should move easily around the piston grooves.
There can be carbon build up in the piston grooves.
A piece of an old broken ring works good to scrape the
carbon out carefully.

Check that your valves don't leak or clean them up
and replace any seals on the valve stems.

Good luck!
Wayne S.
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