02 wr426 mis at mid rpm


7 replies to this topic
  • byggd

Posted December 18, 2005 - 02:56 PM

#1

Greetings all! My bike has developed a mis at mid RPM. I'm not sure if it's always been there to some degree but I did notice it after installing the JD jetting kit. If I hold a steady throttle it will cut out a little but if I pin the throttle from there it accelerates with no miss. It's been a bit cooler lately (for us anyway, around 65-70), could that be it? Any ideas? Here is my bikes set up:

Model (400 - 426 - 450): 02 WR426
Timing (WR-YZ): YZ with 03 exhaust cam
Main jet: 170
Pilot Jet: 42
Fuel screw (turns out): 1 1/2
Needle model/Clip position: JD blue needle postion #3
Airbox lid (on or off): Lid Off
Pipe: White brothers e-series w/six discs and quiet core insert
Altitude where you ride: So Cal 0-4000 ft
Temperature where you ride: 75-110
Degree of satisfaction: Runs awesome quick response/no bog

  • byggd

Posted December 19, 2005 - 04:50 AM

#2

I've read a few more threads and I still can't find any with my bikes set up but it sounds like I may need to lower the clip on the needle one notch for more fuel. Can anyone confirm my thinking?

  • Matty05

Posted December 19, 2005 - 04:03 PM

#3

sounds like rich to me.
lean off the needle, maybe red #4?
Im at red #4 now, constant 90 - 95's, high humidity, around sea level.

  • Matty05

Posted December 19, 2005 - 04:04 PM

#4

Ive got a 450 though! not a 426.
still might work?

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  • byggd

Posted December 20, 2005 - 12:52 PM

#5

sounds like rich to me.
lean off the needle, maybe red #4?
Im at red #4 now, constant 90 - 95's, high humidity, around sea level.

I seem to have a case of CRS :applause: On the needle #1 it at the bottom correct? So I need move it "up" from #3 to #4 which will lower the needle to make it leaner?

  • byggd

Posted December 21, 2005 - 08:04 AM

#6

I seem to have a case of CRS :bonk: On the needle #1 it at the bottom correct? So I need move it "up" from #3 to #4 which will lower the needle to make it leaner?

As luck would have it I was rememnbering this completely backwords. My manual shows the groves as 1 through 7, top to botton (pointed end down).

sounds like rich to me. lean off the needle, maybe red #4?



Matty, why would you recommend moving the clip from #3 to #4 as that would make it richer. Is it because the red needle is thicker and would be leaner on #4 than the blue is on #3 :applause:

  • Matty05

Posted December 21, 2005 - 05:37 PM

#7

As luck would have it I was rememnbering this completely backwords. My manual shows the groves as 1 through 7, top to bottom (pointed end down).

Yep! Just like your manual (if you have one!)

Matty, why would you recommend moving the clip from #3 to #4 as that would make it richer. Is it because the red needle is thicker and would be leaner on #4 than the blue is on #3 :applause:

I have found through trial and error that my blue #3 is about the same as my red #5. It seemed a bit too rich on blue #3 (sputtered) but perfect on red #5.

Just try a few different positions when you are out riding next. I usually take it for a strap around the street then down a long straight road. It doesn't take long to make a judgement.

I just use 2 allen keys, phillips head screwdriver, and small pliers to get the clip on and off. Just undo the airbox off the carb and Pull the boot off the back of the motor and leave it on the carb. This gives you enough room to rotate the carb to get to the needle. Be careful if it is all dusty, you might want to wipe with a rag first.

  • byggd

Posted December 22, 2005 - 05:01 AM

#8

Yep! Just like your manual (if you have one!)



You mean one of those $80 paper things with all the words and pictures? Yup, I got me one of them




Here is what JD had to say about the miss.

The steady speed miss is ignition related. Try disconnecting the TPS plug to see the effect. This is a common symptom of Yamaha WR's that get ridden on pavement.






 
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