93 X2 - low compression

B

blue89turbo

Location
ontario
Hey guys,

So i think that I have owned this X2 for about 8 years and she has run pretty good.

But i think it may be time for a rebuild.

I just checked the compression. its at 115 front and 125 rear. Also I had to get it home last summer and it was missing most of the ride home.
I had it running yesterday and it was running rough and back firing and there is a lot of black soot on the hull at the exhaust.

I want to have her running good for next summer so I am thinking of doing the following this winter:

redo top end
new reed valves
new carb kit
new coil wires
new plugs

I am handy but haven't redone pistons or rings before

What is the basic procedure? I take the head off and take it to a machine shop where they hone it if everything looks good and tell me what size rings I need?

Any other tips or suggestions?

Thanks
 
Mike W

Mike W

Infidel
Location
North Florida
Assuming you are at standard (stock) bore, you can take the cylinders and pistons to a machine shop so they can check everything to see if it’s out of spec. If so they can just hone the cylinders and get new rings for whatever size pistons you have. If not then it will need to be bored one over (.50) and purchase the correct size pistons.
 
wmazz

wmazz

Location
Riverside, CA
650 engines have problems with the piston rings rusting when they are
exposed to moisture inside the exhaust port. As a result the ring barely
makes contact with the cylinder wall on that side of the cylinder.

It is common for good quality compression gauges to read 30psi low.
Hopefully part of the problem is your compression gauge. Standard
650 compression is 165psi.

With rust a possibility, and the front cylinder reading low, I recommend
that you remove the flywheel and stator to inspect the front main seal
and the nose of the crank for rust damage that will shorten the lifespan
of new main seals.


Bill M.

The flywheel cover frequently allows water in, but doesn't let it leak
out.

When the front main seal wears out, the engine sucks rust from the
flywheel & stator through the main seal and into the front main bearing.
 
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