Jetting for WR muffler?

2 replies to this topic
  • Jaffa

Posted February 20, 2007 - 12:21 PM


I have a 99 YZ400F that currently has a white bros e2000 pipe on it. Unfortunately it's way too loud, so I'm going back to a stick pipe. However, I also need a spark arrestor so I bought a WR400 muffler for it. I'm confident it will fit okay, and I know there will be some power loss (actually I'd prefer the power delivery to be less "snappy" anyway).

I understand that I'll need to re-jet. I'm about 1000' above sea level, and was wondering what the best (cheapest) way to find the correct jet was.

Right now I'm thinking about taking it to my dealer, but that's going to be expensive.

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  • Ga450owner

Posted February 20, 2007 - 04:23 PM


never take a bike to the dealer for rejetting...As a dirt bike owner,
you need to learn the ins and outs of is relatively easy -
record what it is currently
Check the manual for the stock jetting settings
modify the jets according to your results and altitude
Chances are if it is jetted correctly for the WB - it will be fine for the stocker:thumbsup:

  • Jaffa

Posted February 21, 2007 - 10:54 AM


Thanks for the advice. I'll check the manual and see what's in the carb.

I put the WR pipe on last night, and it seemed to run fine. Sounds quieter, but has a really low tone to it now, sounds really awesome :applause: Still seems a little lean (previous owner said he had it set up lean for more power), but seems a little better too.

Can't wait to go try it out :applause:

I hoping that if the jetting is wrong it will just perform badly rather than breaking anything, is that about right?

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