So, what happens when a KDX overheats?

[cbova]

As the subject states... Picked up a non running 97 220. No coolant in the rad or tank. There was coolant behind the flywheel cover. The engine was apart shortly before I acquired it. The guy I bought it from only had it for few months before it popped. He said it died while riding. Oil was milky. I haven't pulled it apart yet but I'm guessing it drank the coolant and overheated. What typically happens if that's the case? Should I plan on a re-plate? trying to decide if if it's financially viable for me to rebuild it. The rest of the bike it's mostly complete; she's definitely been run hard, put away wet, as they say.

[kdxdazz]

I cooked my 220 engine when the impeller spun on the shaft, nothing bad happened to the nikasil but piston and rings were badly worn, it also seized a power valve and broke it, but I think there are also different levels of overheating, mine was still running

[KDXGarage]

I would have a machinist to check the base of the cylinder, the head of the cylinder and the cylinder head for flatness. Warping might be an issue.

Also, crankshaft, ever bearing, etc. is suspect.

Are you sure it was coolant by the flywheel?

[cbova]

Thanks, 100% sure it was coolant behind the flywheel cover, it was ethylene glycol green. Rad and tank were bone dry. There is also an issue with the kick starter. It slips for part of the stroke so I didn't do a compression test but it felt pretty low. I'm planning on at least a piston/rings and full gasket/seal set. If the inner crank bearings are bad it's probably not worth it for me.

[bufftester]

The only way I could see coolant behind the flywheel would possibly be a bad head gasket that pulled coolant in to the bottom end of the crank and out the crank seal, not really likely IMO, more likely to have come in through the cover. The milky oil however is definitely coolant and likely a bad water pump mechanical seal, or blown head gasket. The kickstarter is a known issue and is easily (though not cheaply) fixed by replacing the pawl gear and spring. For not much more I'd just crack the case and replace the bearings for peace of mind.