Subject: Re: Bad Piston?
Author: Matt Moore
Date: Apr 7, 2005, 7:39 AM
Post ID: 1718664034
Oger,
is there any kind of ridge at the topof the cylinder, where the rings
stopped scraping. Run your fingernail across it. If it catches your
fingernail, then there is enough there to damage a new set of rings. If this
were a regular iron bore (like a car/tractor engine) you would have to use a
ridge reamer to remove the ridge. since these are chrome lined alloy, if
there is a ridge, it might be best (not cheapest tho as others have said) to
put on a new set.
Mine had a big pile of junk in the bottom of the sump, and when I
disassembled the motor, lots of chrome flakes were embedded in the bearing
material of the big ends and main bearings.
Have you taken the rods off the crank to see if those bearings are OK? Might
be an idea to check that while you're there, with plasti-gage if they look
in good shape (no scoring, grooves...)
Another way to tell if chrome has flaked off is to look at the rocker
spindles and see if there are little bits in there, and scoring of the
copper bushings. Mine also had this damage.
What I was surprised about was that with the bores as loose as they were
(.005" OVER the max service spec at the top of the bore) and as messed up as
the bearings were, it still ran fairly well.
Now that I have rebuilt it with new pistons and Nikasil cylinders, WOW what
a difference.
Not saying that you could not re-ring and have a great running bike, just
thoughts.
YMMV
Good luck
Matt in MI
1973 Eldo