Re: Clueless about two strokes!
- From: "Alex" <weissmans@xxxxxxxxxxx>
- Date: Sun, 8 Jul 2007 16:23:06 -0400
Get the cylinder honed with a ball hone and check the piston after you have
it out. 125's are usually run very hard and a new piston is good insurance
against catastophic failure. Also check the rod big end and main bearings
while you have the cylinder off.
HardWorkingDog" <harvey@xxxxxxxx> wrote in message
news:harvey-8DBDE8.17592807072007@xxxxxxxxxxxxxxxxx
In article <15180-469025F2-607@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
AWR7MMSTW@xxxxxxxxx (Mike Corey) wrote:
As the subject says, I'm clueless about modern two stroke motorcycle
engines. By modern, I mean anything liquid cooled. I have vintage two
and four strokes, and repair them myself, but the newer bikes I've never
worked on, until now. The bike is a 1999 RM125 Suzuki. Got real hot.
Very little compression, so it will not run. I replaced the o-rings on
the head because they were discolored, still low compression, still will
not start. Must be the rings, right? Cylinder bore looks good. Can I
just replace rings? Or piston and rings? Is the bore plated? So the
piston and rings will be a standard size? No over sized pistons with
plated cylinders, right? Thank you.
It's too bad Eric Gore took his stuff off-line, here's his book that
will give you some pretty good info if you're the book type.
http://books.google.com/books?id=4MealMAQSeIC&pg=PA9&lpg=PA9&dq=eric+go
re+2+stroke+tips&source=web&ots=14B8mPPwlA&sig=cgxunq-nrGOa_x8xz7MFXti_
UEU#PPP1,M1
The above link shows some basic stuff you probably already know, the
juicy parts about rebuilding the top-end on a water cooled bike isn't
displayed.
First, get the Suzuki Owner's/Service manual. It'll tell you most of
what you need.
Second, the piston on these bikes is considered a wear item, and
should probably be replaced at roughly 10-15 hours of hard use. If
you're going to the trouble to replace the ring (probably just one)
I've always figured may as well do the piston too, as well as little
end rod bearing and all the o-rings and gaskets. Take a look at the
power valve while you're in there (if it has one.)
The bore is plated, so the only way to repair it is to have it
re-plated (normally the replater will send you a replacement cylinder
and refund the core charge when you send in the old one) or replaced
with new.
The tolerances are pretty tight, so they normally size the cylinders
from the factory in four steps, each a few thousandths of a mm apart,
with corresponding pistons to fit, based on how each cylinder comes
from the manufacturing process. If your cylinder is in good shape,
you'll need to figure out which cylinder you have to order the correct
piston.
I could be off with some of the details as I've never opened up a '99
RM125, but good luck!
--
Charles
'99 YZ250
.
- References:
- Clueless about two strokes!
- From: Mike Corey
- Re: Clueless about two strokes!
- From: HardWorkingDog
- Clueless about two strokes!
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