12 replies to this topic
  • wvbob

Posted August 21, 2004 - 06:38 PM


99 wr400 jetting help
i bought a 99 wr400 have changed throttle stop,opened up airbox,put on a stock yz pipe.all jetting is stock.i ride 500-1500 ft, 60-80 temp.need jetting suggestions.

  • wvbob

Posted August 23, 2004 - 02:57 AM


this is first bike in 25 years, very first 4 stroke. could really use some jetting help.

  • ovrrdrive

Posted August 23, 2004 - 03:27 AM


Well, to start with, how is it running now after your mods?

Does it pop and backfire when you decelerate?

Does it bog down when you accelerate?

Have you pulled the plug and inspected the color of it?

Adjusted the fuel screw?

A little more info and we can probably come up with some suggestions. :thumbsup:

  • wvbob

Posted August 23, 2004 - 04:52 PM


no backfiring or popping on acceration, no bog,have noticed slight popping on deceleration.sometimes have to use choke even when hot.fuel screw adjustment does not seem to change anything.plug looks ok.45 pilot jet, fuel screw 2 turns out,stock needle 4th slot,172 main jet.seems to run good with mods, but being new to this bike i am not sure how it should run,thanks.

  • wvbob

Posted August 28, 2004 - 06:41 PM


hey guys, anyone have jetting info for this bike and mods?

  • MN_Kevin

Posted August 28, 2004 - 06:57 PM


my BEST advice is to buy yourself the JD Jetting kit. Many of us have, and are COMPLETELY happy. I spent mucho $$$ and YEARS working on my jetting. I have a buttload of needles and main jets to prove it!!

FACT: Thumpertalk was conceived on the lack of knowledge of the carb on the 98/99 WR400 >> this IS absolutely true!!

JD (James Dean) was one of OUR carb guru engineers working out the jetting issues of his 99 WR.

After MUCH R&D, he has designed his own custom cut needles. His kit somes w/ two needles and several main jets AND instructions to jet properly.

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • ovrrdrive

Posted August 29, 2004 - 03:00 AM


From your descriptions, it sounds like you have it dialed in pretty well. If it runs just like you say, I wouldn't change a thing.

It is fast right?

Oh and if you feel like investing the money for it, they say the JD kit is night and day over the stock stuff...

For my needs I think the cheaper stuff will work fine. I don't race it.

  • wvbob

Posted August 31, 2004 - 02:41 AM


found out why fuel screw makes no differance.the tip of the screw is broke off blocking the passage shut. anyone know how to get this out? it is stuck solid. thanks.

  • Hamish

Posted August 31, 2004 - 12:31 PM


you could try compressed air from the other side of the passage.

  • wvbob

Posted August 31, 2004 - 06:04 PM


i tried compressed air, also tried a wire, that did not work either. may need a new carb?

  • tcmII

Posted August 31, 2004 - 06:18 PM


You should give the folks over at Zip Ty Racing a call. I remember a post from someone that broke their ZipTy screw and they were able to get out the broken piece. Maybe they can help you.

  • wvbob

Posted September 01, 2004 - 01:35 PM


thanks,i"ll try them. it is a zip-ty screw.

  • wvbob

Posted October 09, 2004 - 05:36 PM


zip ty racing did remove the broken fuel screw and replaced it with a new one -no charge!


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