1991 kx 250 engine interchangable?

im new to dirt bikes and 2 stroke engine and pick up a 1991 kx 250 2 stroke as a project to go out and ride with a few friends.


when i bought it i was under the impression it was a 94 and turns out its a 91, seems that internal engine parts are harder to find for this year. the engine has a seixed crankshaft and bent rod


my question is am i able to put a newer engine say 92-01? with few modifications or the newer bottom end with my 91 top end

ive rebuilt and built plenty of race cars and engines and generally know my way, but dirt bike are a whole new ballpark for me!


thanks for any help!

You could buy a and install a later model engine relitvely easy I am sure...but I would not franken a later model bottom end to a 91 top end...It might work but you are asking for troubles in the long run.

I would just keep watching ebay for the parts to rebuild your 91 and keep it as close to oem 91 as possible.

As for the crank..You could just have a shop put a new rod on your crank halves I am sure.

Thanks for the reply!, I picked up a running 1988 kx125 last night that's in rough shape but it runs great, is it possible to fit that engine on my 250 chassis? Reason I ask that is the 125 frame needs some welding in a few places

I would just split the 91 kx engine and then have a shop like oconnor racing or a quaified person rebuild your crank. I have a guy by me that will rebuild cranks for about $80 plus parts.

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