99 WR400F YZ Timed =Jetting Issues?

2 replies to this topic
  • Tripwire

Posted December 23, 2004 - 10:05 PM


Last night I YZ timed my WR400F and started it today (well barely). I also raised the jet needle one clip putting it to the center position (it seemed to be a bit lean on quick throttle application during my last ride). At any rate when I started the WR today the jetting seemed way too rich. It smoked black smoke when revving quickly and didn't want to idle very well. Overall it just appeared to be running too rich.

I currently am running:

The stock pilot (45) with two turns out.
175 main jet (168) stock
Stock needle in Center position
White Brothers E Series pipe with spark arrestor insert and 5 plates
White Brothers header (but dented a bit by previous owner)
Air box snorkel removed but top lid still on

Temp today when running around 45 degrees at about 450 ft above sea level, foggy with high humidity.

I took the time to put the bike back to WR timing (just to make sure I didn't mess anything up) and it ran fine a bit richer from the needle setting but nothing at all like it was with the YZ timing. It idled perfectly fine!

So my question is whether the YZ timing effects jetting?

Also, while I'm at it do you loose any bottom end by going to the YZ timing?

Thanks in advance!

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  • stumpyten

Posted December 24, 2004 - 12:20 PM


Hi i have a 99 wr that i ran yz cam timed until the granite lanes here in cornwall uk, just got to slippery for the savage power delivery the yz timed machine produces. so its wr timed now for the winter,Anyways i left my wr on standard jetting with the airbox top removed and an oshiro enduro pipe would try leaving the float needle as was for wr and go from there.Whilst on yz cam time you will loose bottom end chugability, but gain mid range and top end the bike will also become really snappy right of the bottom not unlike a two stroke you might have to increase the tickover as the idle is slightly erratic

  • Tripwire

Posted December 24, 2004 - 06:44 PM


Thanks for the feedback.

It felt like it wanted to be leaned out and that would help substantially. I have been riding two strokes and would really appreciate the snappy two stroke like bottom end but where I live there is a ton of slippery clay on worn out rutted trails so will probably leave the timing alone until spring or the next valve adjustment. Somehow that chugability in the snotty sections is too much to resist and I can always take my WR250 two stroke out when I'm looking for some snap!

Thanks again and Merry Christmas!


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