02wr426 bogs and stalls out

7 replies to this topic

Posted January 29, 2002 - 11:57 AM


I just bought a 2002 wr 426 , i uncorked the exhaust , removed airbox lid , had throttle limiter cut down and at same time put in #170. Now when i yank the throttle back it bogs down and stalls out.I ride in So Cal. Any ideas ???

  • mcarp

Posted January 29, 2002 - 12:44 PM


First, not to soundlike an a-hole, but you'll want to perform ONE modification at a time on this bike. Otherwise it's too hard to figure out what ONE change made the bike run worse. For example, if you replace the air filter lid, does the problem go away?

But since just about everyone does what you did, we should be able to help, I won't cry anymore it. Without knowing your temp, elevation, and air pressure, we can only guess though ...

My *guess* is you are now running lean as you've just introduced much more air in the mix. First thing to do is find the FUEL SCREW on the bottom on the carb. Turn it counter-clockwise ever so slightly, about 1/8 turn. Now ride it for a minute and see if the condition improves (it may still exist, we're looking for an improvement).

If it does get better, continue to turn the fuel screw out slightly. If you've gone past appx 2 turns, purchase a #45 pilot jet and install it. Warning, it's been found after 2 or so turns the screw could fall out, which is killthe bike's power delivery. Return the screw to the stock postion after installing the #45 jet. This should be helping...butyou may not be done yet.

Is the condition getting better? yes--continue to play with the fuel screw. No- Move clip position on the needle down- from #3 to #4. Is it getting better? If not, put back on the stock main jet and try again. Better? No-try DVR needle OR a 165-168 main. Yes? Cool, continue experiment until you find Nirvana.

Major note--There are plenty of people that adjust the carb ever so slightly, the bike runs better and they stop adjusting it. DO NOT do this! There is SOOO much power/smoothness/rideability to be had with good jetting. You've done the free mods, now spend a little time and a few bucks (probably around $25)
with jets.

Another note--Some WR riders including me NEVER could get the bike well (not just OK, I mean RIPPING well) w/o changing needles.

James Dean has a jetting guide for sale that is probably going to help you immeasureably. If I didn't already go through this game a million other times I would buy in a heartbeat!

If you're really ballzie and want to try totally different settings, go for it, but write down all the changes and your riding observations. After a while it's hard to remember what worked and what didn't.

Many WR timed riders have had luck with:

DVR needle, #4 or 5
48 pilot w/ #100 main air jet
168-172 main jet
stock everything else.

Don't take these settings as gospel, really don't know what elevation/temp/etc you ride in which changes things!

Also, something else. When new, the engines are tight and may not run all that great until you have an hour or two on it. Also, the air filters are dry from the factory which will exacerbate your condition (leaner). Check to ensure there's oil on the filter and that it's sealed well.

If these ideas fail, post your elevation/temp/humidity, riding areas, and other conditions you've noticed.

One other thought--if you are wacking the throttle from zero to WFO, you probably need to learn to roll the throttle on a little more gracefully. It's difficult to jet the bog out of the bike if you wack it hard like a foos-ball game! Roll that puppy!

  • mcarp

Posted January 30, 2002 - 05:28 AM



Please post if you've had any success with the above tips. Can anyone else offer help for Dan?

  • SoCalWR426

Posted January 30, 2002 - 05:43 AM


Dan, I kinda think your running rich. Usualy a lean condition results in back poping. Try a 165mj. my buddy's 02WR 426 is set up like yours, his is still running stock jetting. it's a touch lean here at sea level but he say's it works well in dez. Does'nt make sense to me unless uncorking alone just does not let enough exhaust flow to make that much of a diffrence in jet's.


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  • okieguy

Posted January 30, 2002 - 06:11 AM


My 02 wr426 also had the bog once I uncorked. Got most of it out by turning the fuel screw to 2 1/4 turns. (stock jetting)

I think the pj should go to 45 but have not had time to change it out.

Hope this helps



Posted January 30, 2002 - 04:12 PM


MCARP AND ALL OTHERS WHO OFFERED ADVICE:;Thanks alot for all the tips and advice I rode today in the snow and froze my @ss off but my bike is running much better. Yes it is still a work in progress but my buddy's 02 xr 400 was behind me all day. Thanks again for all your help.


  • SoCalWR426

Posted January 30, 2002 - 04:47 PM


I woulda been riding with you if I knew you were going!! I rode yesterday at Ballinger, It could have been awesome. big flakes of snow coming down,traction was awsome, It was a spectactular day. Had a real newbie (sp) who's alway's talkin sh#t. Showed 1hr late and still needed oil, pre-mix, gas, plugs and lube chain. 1990 RM250 piece o crap no maintaince whatsoever. Got there 4hrs late, took 45min. to get RM to lite. Newbie overstated skills just a wee bit.(go figure) Did a 2nd or 3rd gear face-plant on a flat road after 15min of ride and then wanted to go home :) Yes there was murder in my heart! Anyway where was I. Oh yea, Dan, if you need a riding partner during the week let me know..Disclaimer: I usualy love to have new rider's. I really like to see new people enjoy the sport and get into it, the look in their eye's as they describe their 1st taste of riding gives me that warm fuzzy feeling..But this time, well I guess you just had to be there to understand.


[ January 30, 2002: Message edited by: SoCalWR426 ]

  • mcarp

Posted January 30, 2002 - 08:48 PM


Snow? In SoCal? It was 66 on Sunday in Ohio! What's up with that?????

Dan, great to hear the bikes' running better. Keep dialin' her in!


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