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RM85 Altitude Changes, Jetting Compromise???

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I'm looking for opinions from those who have experience with what I am asking in this post.

My 11-yr old Grandson just moved up to an RM85 (new). We live and practice at locations from 3000' - 4200'. I changed the pilot, main, and clip setting from stock before we even broke-in the bike. RM is running well across our 1200' changes in practice tracks all but a tiny bit rich overall. 1/4-turn on the air screw is all I need to change between the 3000' track, and the 4200' track.

My concern is with regard to the two organized race tracks we visit.  One track is at 200' elevation and the other track is at 1000'. 

If I stay with the slightly rich jetting we are using now (3000' - 4200'), would you expect, guess, or know-for-sure that I am going to have to physically change overall jetting to run across all the different altitudes I mentioned, or would you think we will be close-enough with just air screw, and idle screw changes?

My Grandson is Junior class average skill level and rides as much 'off-the-pipe' as 'on-the-pipe'.


Our current setup is as follows:

Main - 125 (128 stock).

Needle - stock with clip moved up to second slot from top (third slot stock).

Pilot - 45 (50 stock).

Air Screw - 1.75 - 2.00 out (2.00 stock).

Gearing - 14/49 (14/47 stock).

Mix - 32:1 premium pump gas.


Your opinions are appreciated.

Riley85 02.jpg

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