Rich or to tell?

3 replies to this topic
  • ddialogue

Posted August 30, 2002 - 02:43 AM


Are there obvious signs of rich or lean conditions (other than pulling the plug) that can help in jetting a WR? I know that popping on deceleration is one symptom of a lean condition. I used to ride a KX500 and jetting it was easy because you could 'feel' when it was rich or lean and jet it accordingly. However, this WR runs so good all the time that I'm not really sure. I know it's on the rich side just by looking at the plug and I'm changing the plug every month (one fouled, two almost fouled.) I'm just finishing up with the BK mod and was going to richen the main jet circuit to compensate but may just leave it where it's at.

[ August 30, 2002, 05:45 AM: Message edited by: ddialogue ]

  • Taffy

Posted August 30, 2002 - 07:40 AM


in my three years on TT i don't think i've seen anyone get so much wrong in one post, well i have but this equalls it.

you don't compensate your MJ just coz your APJ has been done.

it'll pop on decel as long as it's not flooded, sometimes more, sometimes less but don't go by that.

you can't tell anything by looking at the plug except that the bike still runs.

rich is soft, woolly, dead noise, accelerates well.

lean is a misfiring, overheating, pinking, knocking, open the throttle and nothing but a vibrating misfiring blue beast.

if you phrase the question right, such as "how do i correct the jetting which at present is fouling plugs galore" we will tell you that you make one change at a time and feel the difference. words can't easily describe something you haven't tried.

however if you've had even a little go we can fill your knowledge bank to the hilt.


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  • ddialogue

Posted August 31, 2002 - 03:33 AM


Fair enough. Let me restate my question. My 02 WR426 has fouled several plugs in the past few months and has a MAJOR bog off idle when the throttle is flicked; so bad that the motor will stall if you hold it wide open. Several posts I have read here on TT gave me the impression that the BK Mod would resolve that issue, but after having completed the mod (with only .50 squirt on APJ) the bog off idle is still there. Spark plug tips look like they've been painted black (I supposedly can't tell rich or lean by looking at the plugs.) Here is the information I have currently: 165mj, ? (stock) maj, 65 starter jet, ? needle (stock) at second clip from top, 42 pj, ? (stock) paj. I will find out what the stock maj, paj and needle is.

[ August 31, 2002, 06:34 AM: Message edited by: ddialogue ]

  • Taffy

Posted August 31, 2002 - 09:32 PM


in my experience the M needle is the one you want. if you ride at altitude get the N and higher they say the P needle is better. you want an E series needle and an M or an N ok?

so ELN or EMM. the rest is out there in the archives for you to see. the needles and MJ's are nearly agreed by all but the low speed Pilot Circuit (PC) stuff is debated.

jetting Qs is accepted as a good good. i originally started with one called "more oommpphh" and bar some amatuer dramatics and me scribbling when i'm pissed it's still valid for your bike as well. read up first and then come back to us if needs be.



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