There are a number of tricks out
there to restore a worn pston and
sleeve and alot of people willing to
give them a try.Too many times Ive
seen guys shelve a perfect car or
plane or whatever because of a worn
engine cause they simply didnt have
the cash for a new one.Below Im
going to list four ways to get quite
abit more life out your engine
starting from the easy to the
damned hard.I have tried all four
and have had good results with
three of them.
1.Add castor...Older cast iron piston
and sleeve engines used castor oil to
achive compression instead of a
taper.The same holds true for a worn
ABC engine.Infact I have engines
with gouges on the piston and
sleeve that operate because of extra
castor oil I put in the fuel.
2.Sleeve pinch...I failed with this
one.The idea is to pinch or compress
the the sleeve to improve
compression.One way is to use a
hose clamp and very lightly tighten
it around the sleeve and heat it up
on a stove.Then you chuck it in
water to cool it and the sleeve will
keep its pinch from the heat
treatment.I dont care who says what
but this is the worst way to treat
your engine and you will destroy it
because you wont get it perfectly
round.The better way is to send it to
be done by guys who have
destroyed alotta engines perfecting
the art.They seem to have great
success and alot of peaple are happy
with them.My problem with it is that
while its true that the sleeve does
wear,the piston is what wears the
most and causes compression loss.
3.The ball bearing trick...Right,take
your piston and remove the con rod
and pin.Now get a perfectly smooth
flat surface.Now find a ball bearing
that will fit perfectly inside the
piston.The fit should be loose.Now
place the piston upside down on the
flat surface with the bearing
inside.Now the idea is to tap on the
bearing to expand the piston
abit.Tap,fit tap,fit tap,fit.You get the
idea.What you use to tap the bearing
with is up to you.I used a shaft with
a light hammer.
4.Cut a oil groove...Although this one
is the hardest,I like it best.If your
nitro rc piston to liner fit becomes
less that perfect, it is EASY to refit the
piston to the liner. Buy yourself a
VERY GOOD tubing cutter from Sears (
http://www.sears.com/shc/s/
p_10153_1...0P?vName=Tools) about
$32.00. It will be a once in a lifetime
purchase that you will use over and
over. Don't ever ever ever ever use
this cutter for anything else. The
wheel that comes with the cutter will
last almost indefinitely, but you
should pick up a pack of spares.
Keeping the cutter razor sharp is
critical.
OK, now I will tell you how to use
this tool.
Almost all nitro rc pistons have an oil
groove at the top of the piston. It is
usually VERY NEAR the top of the
piston. If the piston does not have an
oil groove, it is easy to make one
with the tube cutter. The cutter will
EXTRUDE the aluminum in the oil
groove making the piston tighter in
the liner. It is CRITICAL to be very
careful here not to get the piston too
tight. You want to push the piston
up into the liner and when it stops,
look into the exhaust port and see
the wrist pin in the MIDDLE of the
exhaust port window. This is exactly
how tight you want the piston to fit.
This re-fit of the nirto rc piston can
be done over and over. The fit will
go away quicker than if the piston
was perfect to start with, but this
method will recover a loose fitting
piston/liner.
I didnt type out the last one,just
some pirate copy/paste.I didnt come
up with any of the methods myself
but I can tell you that if done right
each method will work and give
your engine that extra life.Enjoy
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