1990 kTM 250 EXC Parts Needed and Engine Repair Questions


Jun 4, 2007
I have a 1990 KTM 250 EXC and the engine overheated due to a corrosion perforation in the water channel near the impeller in the clutch cover (the clutch cover bolts to the RHS engine half and houses the water impeller). This caused water to be depleted from the radiator/coolant system and ran dry for several minutes during high speed race. I did minor damage to the cylinder wall (KTM mechanic said it is not that bad) but one of the two piston rings is seized to the ring channel, where the heat was generated mostly on the one side of the piston.

Question: #1. Has anybody encountered this problem and rectified it by prying ring out and subsequently filed the ring channel using the old ring or a small file?

#2 How hard and involved is the splitting of the engine and replacing a crank for an experienced back yard mechanic with no experience/specific tool for breaking down a KTM bike motor? It is hard to tell the condition or if there is any damage from the water entering the bottom end of the motor.

Parts needed:

1) Clutch cover water impeller housing, KTM P/N 546.30..001.000

2) Piston w/ 2 rings for KTM 250 EXC Standard Bore @ 67.5


3) Top end of engine. ie. Piston + Cylinder set (if available for KTM 250 EXC) for somebody parting out a 1990 KTM and can sell both.

Thanks for any and all replies to my dilemma. I am hesitant to spend a whole lot of money on this bike as I bought it for $500, but love riding it for its power.

Dave in VA
Jul 18, 2008
1990 KTM 250exc

alright, I just bought a 1990KTM250exc. It has been many years since I have been an off roader. What advice can yo give me on this perticular bike? Thank you much Bruce

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