Replace jet or adjust clip?

9 replies to this topic
  • redmanrandyed

Posted August 12, 2003 - 08:54 AM


My BRP is bogging down when I ride around 7000' in elevation. :)
I live around 4500' and the bike does well at this elevation. I ride around 4500' to 9000' plus.
I currently have the 172 main jet installed, needle clip in third position. I beleive it is running too rich and that is why it is bogging down in higher elevations? It runs well at 1/4 throttle at high elevations but if you rev it up to shift into second it bogs down terribly.
Should I move the clip or go with a 170 or 168 main jet? Is there something else I could try?

Thanks in advance,


  • stonewall

Posted August 12, 2003 - 09:50 AM


I would say you are definitely too rich on the main. I live around 4000' and the 172 runs rich here. At 7000'to 9000' you probably need to go even smaller than 168.

  • Moredesert

Posted August 12, 2003 - 01:30 PM


I'm running a 165 main with the up grade neddle on the 3rd clip. I ride sea level to 6000' and I have no problem. I say drop the main to 162-165

  • smashinz2002

Posted August 12, 2003 - 06:01 PM


Simple solution: Drop the main to a 160 for over 8k, use a 165 at 4k. Set the clip in the middle.
Make sure the bike is uncorked properly; 40mm intake boot, airbox baffle plate and snorkel removed, and use either the 40mm exhaust tip, or modify the stock tip to 34 or 36mm.
I ride my bike from 8k to 12k regularly during the summer, using those settings. It never bogs or sputters. For the bike to run rich enough at the lowest elev. of 8k without getting too hot, the bike should be jetted for such. Slightly over-rich running above 10k feet is ok and desirable to prevent overheating when the going get's slow on the steep rocky switch backs. Also, the thinner the air, the less cooling you get from it.
Going overly rich, such as a 175 jet at 9k, is bad not only because it runs horribly, but also the extra fuel can wash the thin film of oil off the cylinder, causing excessive engine wear.

  • qadsan

Posted August 12, 2003 - 06:27 PM


I also agree with everyone above. Go leaner on the main and your bike will run better.

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  • Rusty_2

Posted August 12, 2003 - 07:59 PM


the extra fuel can wash the thin film of oil off the cylinder, causing excessive engine wear.

Excellent point! That's something that I've argued about and tried repeatedly to get across to buddies of mine who run their bikes pig rich thinking they're doing it a favor. :)

  • smashinz2002

Posted August 13, 2003 - 06:03 PM


No kidding Rusty_2? Funny thing, I've had the same trouble trying to explain that idea to friends of mine also!

  • billoyd

Posted August 13, 2003 - 07:52 PM


All this bickering? I am leaving sea level with a perfect running big gun race core, uncorcked @175 jet, going to Colorado (Black Bear, Engineer, Cinnamon, Imogene then Pearl pass, Italian Creek. Off to Colorado cycle fest for 2 more days of dual sport. I just finished doing the Quiet core full repack and a 155 jet, hopefully I nailed it? But I will carry a 165 just in case? Any one? Any one? :)

  • Moredesert

Posted August 13, 2003 - 08:04 PM



I guess with the bung hole pluged up like that you should be able to get away with a 155-160 main. Wazn't stock a 152? :)

  • billoyd

Posted August 13, 2003 - 08:17 PM


Need to get another tail section to handle the top speeds and hot sauce in Baja! But 3 or 4 times a year, have to put a muzzle/butt plug for the Feds!!!! Tough to keep everyone happy?

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