calling jetting gurus, your guidance please?

Hey everyone.

I am replacing the sealed restrictive stock muffler on my australian 2000 wr 400 with a lovely new bills pipe.

I need a bit of guidance with what my jetting requirements might change to, going to an open muffler. I followed taffy's advice when I was jetting it for the stock pipe and he was pretty much spot on. I am running a-

42 pilot

75 paj

160 main


obeln pos 2 or 3

wr timing, airbox lid off and bk modded. Always starts 1-2 kicks, never a hint of backfiring, plug fouling or any type of misbehaviour.

In my opinion I will probably need go up to a 45 pilot and a 165/168 main when I fit the pipe(tomorrow).

Can one of you jetting gurus confirm this?

Will I need to richen up even more than this?

Should I go back to the stock obdrq needle?(doubt it)

Should I just see how it goes with the current jetting first?

I would like to be "in the ballpark" pretty much from the start if possible and would really appreciate any feedback I could get from you jetting gurus out there.

I've read the jetting Q,s post and this is what leads me to believe I will need to richen up a bit with my new pipe.

thanks in advance for any feedback.

You are heading in the right direction. That should surfice with your altitude.

Bonzai :)

thanks yamakaze, by the way dude, nice pics of the triple clamp and damper setup, looks trick to the max!


oy trundley what's all this dude stuff?

strewth bruce?

your MJ is just about right at 168MJ. but your PJ is already rich and isn't effected by the pipe.

by going up 8 on the MJ you can try dropping the needle one clip. that 75PAJ should have a 40PJ let alone a 42 or 45.

so howzat? fair dinkum?!?!


beauty mate!


Bonzai :)

Fair go, this is gettn too ozzy for me bloke.

I run with an open pipe, 38pj 65paj emm#5 168mj 200maj. I have tryed every combo of jets & this is the best for me.

yz timed aswell.

The 38/65 and 42/75 have been great combinations at idle and off-idle with the same carb on my 400EXC.

EMM#5(ELN#4.5) and #165 main with 200 MAJ also have worked well. You're already running the clip higher(#2-3), keeping the needle lower and leaner. I would just increase the main and give it a test run. Adjust the fuel screw to see where it's at from there.

hey guys,

I just pulled the carb off and set up the jetting as a starting point with,

42pj, 75paj


obeln clip pos#2,

mixture screw about 1.5 - 2 turns

will see how it goes like that for starters and let ya's know.

thanks for the feedback, very much appreciated.


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