Kx 250 how long to run in

Hi there I've just re-built my 1990

Kx 250 and during the re-build replaced literally every single bearing in the engine so technically brand new, how long should I run it in for any answers welcome thanks for looking

Your service manual should give you insight on proper break in. I do several heat cycles to break in the top end. Do an oil change than good to go. But that is me. Everyone does things different.

I'll give you my opinion and my way.


I do 1 or 2 heat cycles on the stand while checking for leaks, etc. The take it out back for a few easy laps continuing checking things. If all looks good....Run it like your're racing it. If it's gonna blow, it'll do it then and there's nothing you can do to deter it. It was gonna happen eventually.


But that's me. Most will have their own ways but mine has always worked for 30+ years and never had an issue.

Thanks for the replies just thought I'd check so's I don't blow it lol, that'd be just my luck lol

Break em in hard they run hard.

Cylinder pressure seats rings. PERIOD.



I agreee with Sappers and break in every motor i build that way.. (Including the turbo 4 banger and turbo v8 shit)



2- 3 heat cycles on stand... WITHOUT prolonged idling - just up to temp. Check for leaks etc.


GO for a ride with varying throttle (And braking on the motor) if all is good....then RAPE the &%$#@! out of IT.  

Seat the rings or it will run like shit. 

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