jetting help

I put a obeln needle in my 426 and left everything else stock. Runs good except for when I am in first gear and nail it, as the rpms get high it studders like I am hitting a rev limiter, which Im not. I tried putting in a 168 mj then a 170mj to try and get rid of it, also a 162mj, but didn't. From researching old posts I am confused about when putting in a yz needle. Should I put it on clip 4 and drop the main, or keep it on clip three with bigger mains, or is there a difference. I ride in Michigan around 1000 feet I think. Mods are in my signiture. Any help will be greatly apprecaited.


Your mods and setup are not in your signature. List the mods you have done, current jetting, and the pipe you run, also what clip are you on with the ELN?

Thanks for pointing that out. Mods are in signiture now.


I would suggest clip 4, no bigger than 165 on the main, the 162 would be my choice. Also a 45 pilot may help on the bottom. I have the same bike and mods except I run a Baja Designs Vortip. I run 160MJ, EKN3 and 45 pilot. I have played around with jetting and this is so far the best combo I have found. You should jet a little richer because of the open pipe. Good Luck. I just went from 42 to 45 on PJ and it helped the bottom.

Thanks for the info. How does your plug look with your settings. My plug is black and has been black from my stock settings to now when I rejetted. I keep thinking Im to rich. I will try the 4th clip with a smaller main to see what happens.


I never check the plug. Think the best way to do it is run it WOT, pull the clutch, shut it off and then check it. I exclusively single track, lower throttle settings and I don't think the plug will run real clean. I judge jetting by responsiveness, and not having plug problems. My bike starts great, hot or cold and does not foul plugs. With jetting these 0-1/4 throttle is pilot jet and fuel screw, 1/4 to 3/4 is needle and 3/4 to WOT is main. The circuits overlap a little but if you break it into thirds it is easier to pinpoint the fix. Try the settings I mentioned earlier and I think you will be very close.

I just changed my jetting over the weekend and developed the same problem after jetting. I was running stock jetting with airbox baffle removed and BD exhaust insert. I raised the needle one clip to eliminate the hesitation at 1/4-1/3 throttle and stuck in a 170 main. Now WOT is doing what you described in every gear. Does the WR have a rev limiter? That is what it feels like. I haven't played around with the fuel screw yet. I think I have to lean it out a bit because it was on 2-1/8 turns out when I stuck the carb back in. Any suggestions?


I think the miss at WOT is to big of main. If you are on the stock needle clip 4 with a 165 will be real close. If you are out over 2 on the fuel screw go up to a 45 on the PJ and this will improve the lower throttle response. Start with fuel screw 1 turn out.

I changed the clip to #4, and stuck in the 162mj, it sputtered more and did not have same acceleration. I put in a 160mj better but not as fast with on clip 3. Im debating what to do next. From reading older posts the obeln needle is a richer needle, so it makes sense to me that I should be leaning something out. Clip 3 defenently felt more explosive and reved faster.

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