Yz400f VS Yz450f

3 replies to this topic
  • Backwoodsbuilt

Posted August 27, 2009 - 08:15 PM


Ive got a 1999 yz400f and i was wondering how i can get more balls oout of it. What is the difference between a 400 and the 450 can i just bolt the jug and head on from the 450 on my 400 and call it good or are they different??? Or where can i get a big bore kit for it besides max powers whole 1 kit they make for the 400.What is the cheapest easy way to give it more nuts???Please explain in detail!!! Thankyou

  • yamaha racing 230

Posted August 27, 2009 - 09:36 PM


no , you cant put a 450 jug on a 400

however u can buy a 444 bore kit that uses a 97mm piston , and hotcams that would be a nice upgrade u can use a 12.5.1 piston ore a 13.5.1 piston

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  • 02WR426Cali

Posted August 27, 2009 - 09:47 PM


On his bike he would also need a 426 crank for the 444 kit due to the piston only fitting the larger wrist pin of the 426 rod. You can convert it to a 426 or a 444, check out lukesracing.com for more info. Or you can just mod the 400 with parts such as a high comp piston and hotcams and porting in the head. Do some searching and see what others have done.

  • Backwoodsbuilt

Posted August 29, 2009 - 02:28 PM


thanks for the help

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