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KTM 250 XCF-W 2010 - Strange Motor Issues

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Just reaching out to the group for some ideas on getting my machine running again. After 100 hours a top end job was completed using KTM piston, rings, etc and after the cylinder was serviced by Power Seal with a Nikaseal plating. The usual heat cycle break in and things seemed fine.


On a second ride on hilly, technical trails the bike simply lost power and would not climb hills and died. After a short rest it restarted and we were back to riding. Eventually the bike refused to start and went back to the shop that did the top end job.


They found the bike short on coolant although it never puked any and there were no smells to suggest any coolant was lost - engine ice. A pressure test caused the water pump cover to leak at the top of the seal against the case.


The bottom end of the motor built up pressure causing both the gear shaft seal and the counter sprocket seal to leak oil in a major way. The sight glass was also cracked. Yes the bike got hot from lack of coolant, but does that explain the pressure in the bottom end?


Finally the water pump cover shows scratches where the impeller fins came into contact with it. The oil in the motor does not smell burned and the clutch plates look fine.


Lots of problems, but few answers for the pressure in the bottom end of the motor. Educated guesses welcome.


Ps: We are splitting the cases to dive deeper to try and get to the heart of the problem.




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No takers I see. I'm back with the answer in the hope of helping others.

The motor got hot, very hot. It seems that the the coolant level was low; although, the bike never steamed or puked. There were no outward signs the bike was overheating until it lost power and stopped.

It's a whole new rebuild of the motor, right down to splitting the cases to replace bearings and anything discolored from overheating.

If its something weirded, it's usually something stupid - coolant.

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