Smoother 426 power delivery

10 replies to this topic
  • mikemac61

Posted June 09, 2003 - 04:01 AM


Any suggestions for smoothing out the power delivery for riding tight muddy trails? I don't necessarily want less power, just more control of it. I'm just starting on this bike but I find that with all the rain here I spend more time spinning the rear tire. I'm sure some of it's operator error but I was wondering if there are some changes I could make to tame this beast for slick condidtions. :)

  • jchantzWR400F

Posted June 09, 2003 - 04:25 AM


One quick and easy modification would be to change your stock gearing. You could go up one size on the cs (front) sprocket, or you could go down a few sizes on the rear sprocket. The front sprocket change would be about a $15 investment, and would probably make the most noticeable difference. This would make your gearing a little taller, and would not hit as hard or wind out as quick. The power should still be there.

  • fastmonstr

Posted June 09, 2003 - 04:25 AM


I added a 12oz flywheel weight from Stealy Offroad

  • SFO

Posted June 09, 2003 - 09:12 AM


If you cut your slot deeper into the throttle tube the smaller throttle openings will require more twist hence easier to modulate.
I have cut some 520rfs throttle tubes like this and you can even put some cam on it so it is progressive.
I set it up on a rotary table with a slitting saw but you could probably do it with just a hack saw.
Hope this makes sense...

  • Dean400

Posted June 09, 2003 - 10:19 AM


I have a white brothers tapered head pipe on my WR400, and the low to mid range power is noticably easier to manage. But, it has more power than the stock head pipe. Mine cost about $150.

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  • blue_beast_wins

Posted June 09, 2003 - 10:11 PM


450 cam mod will smooth that baby out, the james now mod and an "e" series needle will also help your low end tourque :)

  • mikemac61

Posted June 10, 2003 - 07:05 AM


Can you explain how a 450 cam would smoothe out a 426? Excuse my ignorance but like I said earlier, I'm new to these machines.

  • blue_beast_wins

Posted June 10, 2003 - 11:38 PM


The 450 cam profile is different to the 426, check out the post on the YZ forum pinned at the top of the page.

  • CraigW

Posted June 11, 2003 - 05:01 AM


As mentioned, add more weight to the flywheel.

The single best improvement comes from fitting the right tyres. If you are running intermediate or hardpack tyres, you will slide all over the place.

Check the tyre catalogs for specialised mud/sand tyres. You will be amazed by the difference in traction.

  • wayneoXCF

Posted June 11, 2003 - 05:25 AM


Stock tires are awful in the mud!
My original 739's had me sliding all over the place. Things got much better when I went to the 756's.

  • fiveoh141

Posted June 11, 2003 - 01:37 PM


Start looking at fly wheel wieght info.


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