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250 break in after rebuild

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I am having to do a complete top and bottom end rebuild on my 01 YZ250. I've searched for a while on break in methods and it's like most everything else I've found about dirtbikes, everybody has their favorite way and everybody else has a horror story about the next guy's way and thinks theirs is the best. I ran 40:1 previously because that is what the last owner ran, although I was just getting ready to richen up my mix when the bottom end blew. I've read it all from run leaner to run 2x as rich to run the exact same ratio while breaking in. Hard break in or go easy? 

 

I'd prefer if you don't give me hearsay. If you broke it in a certain way and your bike blew up (not as a result of incorrect assembly) please tell me. If you have a success story share that too. I've only had this bike for 3 months or so and I'm still brand new to 2 strokes motorcycles. It has been neat learning about it while tearing it down though. Probably going to order a hotrods crank and wiseco piston on Monday. Shouldn't be hard to talk me out of either... horror stories abound. I'd just like to get it back running at this point. 

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warm it up, ride a few gentle laps keeping the motor under a load, let it cool.. or dont. and just ride. 

 

32:1 is what i would use, more oil means

  • better ring seal
  • more power
  • cooler running
  • longer piston life
  • longer piston ring life
  • longer crank bearing life

etc

 

Ive broken in well over 20 motors in every way possible and honestly i dont notice a difference.  Just warm it up and ride, The whole point of a break in is the seat the piston rings to the cylinder. This won't happen at idle. Putting the engine under a load is what does it, So i break stuff in like i mentioned at the top of the post. I dont feel right going balls to the walls on a new motor but I know many who just rebuild, warm it up and ride like they always do and its never a problem.

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here is the manual for that bike, copy this link, paste it in your browser and hit enter it will prompt a download for a pdf digital copy of your manual

 

ymenvom.crestec.nl/new/manuals/M5MW-30.PDF

 

 

read it cover to cover, it will help you alot

Edited by adam8781

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