Pic of rear cylinder. Any ideas?

T

thehurlatron

Location
West Michigan
650sx ran good for about 2hrs on Sunday. (As usual). Then seemed to have lost power. Would start and run in the water m, but maybe 1/4 speed and realy boggy.

Popped off the head and see this. Rear cylinder has creamy goo on head and piston and into exhaust port. Is that water that is mixed in there? Ideas?
 

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Kohldanielzimmer

Kohldanielzimmer

Sierra Nevada Runoff Rider
Site Supporter
Location
Ahwahnee, CA
Yeah, that is water intrusion. I can think of two potential culprits: a) bad head gasket; or, b) crack in your cylinders water jacket. Since the ski's symptoms occurred after warming up the ski (riding for an extended period) you should thoroughly investigate the cylinder for any hairline cracks.
 
T

thehurlatron

Location
West Michigan
Looking at the head before I took it off, all around looked good. Once off, the only part of the head that was milky was the rear cylinder dome. The rest of the head was dry. So should I assume that the head gasket was fine since there were no signs of water seepage from the top?
 
T

thehurlatron

Location
West Michigan
This is the first time the head has been off in 25 years.

Bone stock original.

Should I just rebuild the whole top end while I'm wrenching? Have the cyl honed, new Pistons/rings ect?


There wouldn't be anything in the bottom end that would cause this at all?

Before this issue, comp was 150 in both. Now 150 front 90 rear. Put some oil in, then was close to 150 again.
 
rollin5150

rollin5150

Location
Idaho
do a leak down test on the cooling circuit to see if it is sealed. My buddy did that then filled it up with oil and pressurized the circuit. Found a small bead of oil on his cylinder wall where there was a hairline crack.
 
T

thehurlatron

Location
West Michigan
speedysprocket said:
Is it just me, or does the rear cylinder look rusty? The front looks milky from your picture, and the rear is muddy looking (rusty water).
Click to expand...

The rear one is milky/brown, but once wiped off, really clean. The front one still has 150psi but is very charred looking. Not rusty, just charred on the piston head. Could be my cell pic in the sunshine not helping.
 
Dartman

Dartman

Location
usa
dont buy a reman from sbt
just get a crank from them
buy oem kawasaki seals and gaskets
use prox piston kits
get wiseco pin bearings
have a good machine shop resurface head and bore/hone cylinders
 
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