Cr 85 overheats

[Austin W]

I’m pulling my hair out over here with a cr85 it was overheating not long after I got it home so I rebuilt the top end the oil was milky and used half the coolant in ten minutes of riding. After the rebuild it did the same thing again head and base gasket were blown and cylinder full of coolant after 10 minutes. I just pull the clutch side case off and the water pump looks fine. Not sure what’s causing this. I had the cylinder and head at s machine shop and they said there was no worping

 

[Okiewan]

overheating.looking for advice

 

[The Redrider]

Are you torqueing down the bolts to specs? I have rebuilt quite a few 2 strokes and never had issues. Check your manual for specs, be sure you have all parts sealed up correctly, everything adjusted properly, and engine rebuilt correctly.

 

[_JOE_]

Milky oil makes me think the water pump seal is leaking. That's really the only path for coolant to get into the transmission. Also check to see that the copper washers are present under the head nuts, if there was coolant on top of the piston the head gasket was leaking.

 

[jaguar]

"looks fine" don't mean shit. Replace the water pump seal and make sure the shaft going through it isn't grooved.

 

[The Redrider]

I had an 88 kx-125 that had a nifty site window, all bikes should have one, and I notice the tranny fluid wa milky. Good grief I thought, what next?, so I drained all of the rad fluid, and the tranny fluid, and pulled apart the friggen water pump. Viola! the seal was toast! After ordering the new seal, I was back in bidness!