higher altitude jetting

[mike989]

I have searched the posts, and checked the base line jetting for a 2t. I don't find an answer, or a match to my set up.
My question, what jetting is recomened for my bike at 7-9000 ft, at 65-85 degrees. This is for 2 days only.
I have an 04 300, RB head and carb mod, jetting is spot on, feel and plug color wise, 91 octane, Motol 800, 50-1.
Jets in use are CEK-3 middle pos. 42 p, 180 m, 1.75 turns out, trail riding in hot, dry weather, 2200ft.

The trail's I'll be riding in a month are speed controled and at the 7-9000 ft.
Do I really need to change anything? I'm not running at warp speed, just don't want to loose major power or smoke anybody out.

I can't really test, it's not that type of outting, everybody jumps on their FI couches and off they go. I'm the only outlaw with a motorcycle and a 2t to boot.
Gotta say after the RB mods the mixture screw made a big difference in performance.
I've never ridden a 2t in altitude, so I don't know what to expect.

 

[stainlesscycle]

look for a 2t altitude jetting chart. you will definitely need to go leaner or you will have terrible performance. i'm betting around 170m/38pj or so.. look for a correction factor - i think it's around .94 * mj size at 0ft.

you should not need to change needle clip or airscrew.

 

[dank]

i think there is an altitude chart in the manual. that should help you out. theres a link in the general discussion forum for manuals.

 

[jefgil123]

Mike, I live in Lake Tahoe 6000 ft. and have the RB head mod on my 300.
For some reason the CEK is too lean for mine., I'm running the CCK
in middle notch, otherwise the same jetting. Maybe mine needs richer because
I run the Motul @ 32:1 Works good at 6000 ft.
except the main, you may want to go down to a 178 for starters.

Your's with the CEK may be just fine for starters. Truth is, you won't
know 'till you get there. Fiddling with the needle clip doesn't take long...

Jeff

 

[Nick]

You dont always go smaller on the PJ when going up in altitude. If it was me i would drop the main to a 168, drop the needle a notch or two and go riding.

 

[mike989]

Thanks guys.
Nick your right, I'm over thinking the jetting. It's 2 days and I'll be riding at a slow pace off the power.
I did switched to a 170 main, kept the CEK needle, clip 2nd from the top, and went to a 40 piolt, settled on 1 turn out on the air screw. Took it riding last Saturday at our 2200 ft elevation. Very crisp throttle response.
Did a bunch of plug readings at different throttle settings just before the hit. Putting around just off idle in 2nd, steady throttle in 3rd and 4th, to lugging in 6th at 35mph. Old plug went from dry mocha brown, to a very light tan.
Should work well at 8400 ft.
Saturday was a test, I won't be riding it again at the 2200 ft with this jetting.