Jetting for Altitude guide???

[keith220]

I live in COlorado and ride at 8000ft to 9000ft elevation, Stock is 40 pilot, 148 main, I pulled off air box and have FMF gnarly desert pipe and turbine silencer, What Main and Pilot and Needle position do I run for colorado???

Is there a chart or ratio to calculate?

[Slick_Nick]

Those don’t seem like stock jet sizes to me. I ride around 6000’ just west of Calgary here and I’m on a 38 pilot with a DEK needle and 148 main. RB modded carb and engine, FMF pipes and no air box lid with vForce3 reeds.

[SS109]

For what it is worth, I just ran this weekend at 6500-7300ft. RB carb jetted 148 main, 38pj, CEK-3 (3 = 3rd clip from top). Bike ran good but spooged a bit. Should have probably gone to second clip on the needle.

Best way to get your jetting spot on is to follow the jetting guide found here: viewtopic.php?f=105&t=1156. I would probably start with a 145 main, 38 pilot jet, and a CEK or DEK needle in the 3rd clip and tune from there following the jetting guide.