400 vs. 426

4 replies to this topic
  • Guest_Guest_*

Posted December 07, 2000 - 05:01 PM


I was curiose how much of a power differnce is there between the 400 vs. the 426. and what it would take to get the 400 up to the 426's level. without getting the 420bigbore kit.

  • motoman393

Posted December 12, 2000 - 05:21 PM


the 426's major difference is acceleration it quickly pulls 1-3 bike length's on the 400! It would be real hard to get the 400 to the 426's level (my friend had a 420 kit and ported head and bigger valves and it still wasn't as fast but it made the same horsepower...)this is due to the gear ratio differences between 1st and 2nd gear! You wont be disappointed with either bike you choose! Just my 2 cents!


I get my kicks on a 2001' YZ426!
Friendswood, TX

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  • ETS

Posted December 13, 2000 - 07:30 AM


Don't forget the 426 tranny and clutch problems, that makes the 1-3 bike lenght jump hardly noteworthy.

  • Hick

Posted December 13, 2000 - 01:10 PM


Originally posted by ETS:
Don't forget the 426 tranny and clutch problems, that makes the 1-3 bike length jump hardly noteworthy.

How do you figure? I’ve ridden both and the power difference is definitely noteworthy despite the grabby clutch. Are you saying a ’99 would grenade too if it made 426-like power? I guess the clutch may not last as long…


The 400 makes gobs of power in its own right which means that there is no easy way to coax more out of it. About the only thing I can think of that doesn’t involve an increase in displacement is bigger valves, a porting job (and maybe a cam change) and/or a higher compression ratio (this may mandate race gas however).

Call White Brothers 714-692-3404

If you spent enough money you could probably make your 400 a 426 beater. Of course you could always just buy a 426 barrel, piston kit, and crank assembly :)

  • BBRguy

Posted December 15, 2000 - 11:45 PM


im motoman393's friend, the one with the 400. well it wa a 420, then the engine crapped out.and now it has a new cylinder and everything else is new too. i have a works white bros exhaust pipe,and a works white bros.ultra short muffler and BBR ported and polished head. not bigger valves though. and a white bros filter.also a high compression "b" pistn. its almost as fast as the 01 426...in fact unless the rider is motoman 393 (a fast guy) itll beat it. but i have alot of stuff on it. ok thats all. you cn go to BBR Motorsports web site, and get awesome stuff. www.BBRmotorsports.com

If you aint thumpin, you aint ridin.

[This message has been edited by BBRguy (edited 12-16-2000).]

[This message has been edited by BBRguy (edited 12-16-2000).]

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