Jetting for 5,000 10,000 feet?

6 replies to this topic
  • freestyle250

Posted May 22, 2005 - 01:56 PM


What would everybody recommend I do for my upcoming rejetting project? I ride at 5-10 thous feet. I replaced throttle screw, removed baffle from pipe, and cut the gray wire. And now Im just getting sick of all the backfiring, and I can tell it needs to be rejetted.

  • clark4131

Posted May 22, 2005 - 03:03 PM


I have found that once you get up in the higher elevations about 6000', the jetting can get very tempermental on you. If you can figure out what your average altitude compared with the time spent there is going to be, then that's what I'd jet for. I'm primarily running around 5000' or so and jetted accordingly. When I get up higher, there's a noticeable difference in performance. The biggest sign is where my idle is. I have a SenDec tach and it will register a wide variation in idle speed throughout the ride...SC

  • Indy_WR450

Posted May 22, 2005 - 06:08 PM


Start with a 45 pilot, JD Red #4 and 160 main jet & 40 leak jet for hot summer at high altitude desert. :)

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  • farkawi

Posted May 23, 2005 - 06:14 AM


Here's my current setup on my '05 WR 450. 160 main, 50 pilot, .020" shim washer under the needle clip. (or you can buy the YZ or '04 WR needles that are adjustable) I also removed the AIS with the Lowedog plugs. The bike starts right up now and no popping, backfiring or hiccuping. We start at 5280' here and so far I've only been up to about 7500' where the snow starts. I've no doubt that the JD kit is good albeit pricey stuff, and so many TT riders use it with positive results...but I'm only $10 into my jetting setup right now and won't change unless it is really bad at 10-12000'

  • Indy_WR450

Posted May 23, 2005 - 06:30 AM


Your 50 pilot is a little too rich. 48 would be better at 5000 feet and 45 above 8,000 feet and if you want easier starting try a larger starter jet. :)

  • farkawi

Posted May 25, 2005 - 05:57 AM


Thanks Indy! I had considered the 48 pilot but my local shop didn't have one in stock. Nor does he stock starter jets. I'm gonna spend some time in his Sudco book and order up some more jets next time I'm down at the shop. I did check out your blurb in the jetting d-base and recommend it to all who ask.

  • wardirt1

Posted May 25, 2005 - 10:50 AM


I ride primarily between 4500 and 9000 ft. I have an '04 wr450 with the JD red on #4 clip position, 165 main, 45 pilot, 50 leak jet. This works great for me.


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