Hot start used for jetting clue

Just installed the JD kit for my wr450 yeasterday. Bike runs ok, but at about 1/8 to 1/4 it kinda cuts out and sputters at a steady speed. But whin I pull the hot start lever it almost goes away. I have a 48 pilot jet, blue needle on 4th groove, 170 main,600 above sealevel, 89deg f,and humid any clues. :):D :D

Try a 45 pilot. If you can screw the mixture screw within a 1/2 turn of being closed and it still idles fine, your pilot jet is to big.

I have the exact same problem. With all the same things(altitude,mods, etc.) I asked JD about it and he said to lean out the needle clip a notch or 2....let me know if you solve the problem. Thanks, Denis :)

Chris I have turned in my zip-ty and out but no diff.

When the weather heated up around here my fuel screw also no longer seemed to make a difference where I turned it until it would get within 1/2 turn of being all the way in, idle would finally start to slow and stumble. I dropped my pilot from a 42 to a 40 and my throttle responce and fuel screw adjustibility came back. You can adjust needle position after you get your ability to adjust idle mixture again. If you go to lean on the pilot jet the idle will hunt (high and then slow, high and then slow).

Ronnie Mac,

I think the 89 degrees and high humidity is whats getting you. Jetting needs to be leaner in those conditions. Try clip 3 and you should be good to go. Cooler and drier conditions clip 4 may be it.


Do you have any plug fouling issues with your jetting set up? I installed JD Blue needle clip #4, 170mj rest stock. I went out for a quick spin and ran ok. Then loaded up trailer and went to some trails and right off the bat fouled plug. I'm not sure if the plug was on the brink from my previous jetting or the jd set up did it. I did not have another plug, so I cleaned the fouled one up and took bike out again this time with 165mj and 160maj like in your signiture. Ran good down low then through the mid a little breaking up, and top felt ok, maybe just a little flat. My plug probably wasn't cleaned up to good so I will wait until I put a new plug in to judge.

When I put the new plug in I was wondering if you still use the 160maj with the 165mj because Im debating on wether to go with the 170mj,200maj or 165mj with 160maj. I run pipe uncorked with lid off air box so I can't figure out why my plug keeps fouling. My last set up was eln #3 with various combos of smaller pj/paj and close to stk Mj's. With Jd's jetting 170mj and blue #4 should I even be close to fouling a plug riding aroung 1000ft in Michigan?

Try the red needle on the 4th clip and a 165/160 main. You are way to rich for your conditions :)


I am running stock jetting with the JD blue 4. I forgot to change the MAJ in my sig. (sorry) but its 200MAJ. I rode this weekend, high 80,s and 100% humidity. Had some stalling off the bottom so I went in 1/2 on the fuel screw and it was fine. I have a little over 100 miles on this setup, no plug problems. The jetting is better at 75 degrees and dry air but was not bad when hot and humid. I think the 160 MAJ is to small for the 165 or larger MJ. If is stays hot you may do better with the red needle as Indy said. Also JD replied earlier to a 426 post and recommended to try Red 4 or 5 in the hot humid conditions. I think if you do 165MJ and 200 MAJ, Blue 4 and in a little on the fuel screw when its hot you should not foul plugs, and when the temp. drops to the 70,s hang on. Good luck.

Hey you guys are allright. :) Moved the clip up 2 groves and it helped alot.(thanks Caper).But I did notice that almost with the pilot in or out the idle change hardle any. I hope this weekend to change to a smaller pilot (thanks Desert chris). Since Indy lives so close to me, kinda, I may try the red needle(almost can rejet in my sleep thanks to my new wr450)But sure do thank-U-all for your time :D :D :D

Well I thought I had it licked but was wrong. Indy was on. Moving the clip on the blue needle I thought did the trick but starting sputtering. Indy sugested going to a red needle, and since I couldnt find my pilot jet 42 I changed to the red needle and changed the main jet to 160. Runs great no more sputering but whin I gun it, it hesitates just for a split second never did that before can you help me with that Indy :D:)

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