Elevation Change Backfire

4 replies to this topic
  • WReckless

Posted October 24, 2005 - 09:59 AM


Ijust purchased a 2000 wr 400 a few months ago,prev. owner road mostly
in the woods at higher elevation.
Iwent to a race in the desert at lower elevation this weekend and the bike was backfireing at most hard shifts under acell.
I know i need to change the jetting,however i don't know how to tell what
size is in the bike now. If I take the jet out will the counterman at the local
dealer be able to teel me what size it is? If so what direction do i need to go?
I will be riding in higher elevations later this season,but i don't want to damage the carb or engine by running the wrong jet size when i ride desert.
Some of our rides will start on desert floor and ride to the tree line
is there a size that could work for both? :banghead:
I'm sure this subject has been posted before but any help would be great

  • clark4131

Posted October 24, 2005 - 10:25 AM


The size is stamped on the jet...SC

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  • dbailey223

Posted October 24, 2005 - 11:40 AM


At higher elevations or warmer temps than the atmospheric conditions for which the bike is properly jetted, you should need to lean it out.

FYI--you mentioned "jet" and not jets--there are a few in the carb plus the needle. So, you may have the swap out more than 1 jet and/or adjust the needle clip position.

  • StreetbikePimp

Posted October 24, 2005 - 11:58 AM


Read through the Jetting Database at the top of the forum.

Elevation does effect jetting. Depending on how "high" you climb depends on whether or not you jetting should change.

  • WReckless

Posted October 24, 2005 - 02:33 PM




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