High altitude jetting for 99 WR400

I searched the site and did not see anything specific for this altitude.

My 400 was re-jetted for sea level couple of years ago (don’t remember what the specs were).

I moved the bike to my summer home (altitude is around 7000ft). It back fires on deceleration, also there is a little bit gurgling from ¾ to full throttle.

I dropped the main jet from 175 to 165 – no change. Also dropped the needle clip to the 2nd groove from the top.

PS: I have the stock can with the Baja insert, air box lid removed, and uni filter, gray wire is cut.

What are your recommendations?


3800ft. to 8000ft. I found that a 162 main jet and stock needle on #4 clip all else is stock. At 8000ft. the bike is a little rich but still very rideable, you may want to use a 160 main then tweek the needle for your own liking. :thumbsup:

You might want to try a smaller pilot jet as well, I'm running a 165 MJ, 42PJ, clip in 2nd postion from the top on the needle.

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