I live at about 4800 ft and ride from 7000 to 2500 ft. I put 142f/145r jets in the prairie along with exhaust mod, snorkle and twin air filter. I have not messed with the air screws yet...they are at the factory setting...2 and 1/2 turns if i am correct...someone correct me if i am wrong. Now I figure based off info i have picked up i should turn these about a 1/4 turn based off my elevation and mods. Should they both be turned the same...anyone with similiar setup and what adjustment to the air screws worked best for you. Understand that I may have to ride and tweak but could use some solid info on a starting position. One other thing to confirm...the one closer to the front is the front air screw and the one closest to the back is the rear right...i know that sounds stupid but i remember when i changed my jetting I just put the 145 where the 142 was and the 143 where the 135/138 was...so if someone could just confirm it would make me feel better...and if you where wondering -- no i do not make my living as a mechanic

 

Personally I think for your elevation even with the mods you done 142/145 main's are too rich, but try them for awhile anyway, as far as your air screws, don't bother to count the turn's, listen to your motor instead, after it has warmed up enough to kick the fan on let it idle in neutral and start with either carb and turn counterclockwise until the motor idles down (rough) stop there and turn back clockwise JUST until it idle's back up, then simply go about 1/4-1/2 more turn CLOCKWISE and your done. do the other carb the same way and your finished 5 minute job top's. that way you know you are rich enough for your elevation and bike without being too rich.........

 

Thanks STAKK

The jets sizes are a recommendation from one of the other guys in the area that had similiar mods...I have to say that once the snorkel went on she definitely seemed to be running lean. Do you have any recommendations for jetting at this level...any insight would be appreciated...the more information the better.

Even if the jets are running rich shouldnt the adjustment of the air screws off set that??? I am learning this stuff so be patient with the questions if they seem somewhat stupid...thanks again for your input

 

The air screw's only affect the idle mixture, and about 1/16th to 1/8th throttle, but they do need to be set right, the directions I gave will get your air screw's as close to perfect as can be without an exhaust gas analyzer.... The main jets affect 3/4 to wide open throttle... the air screw's will have no affect on them, If other's at your elevation are getting good result's with the 142/145 main's, then try them for awhile and see how it does, if you lose top speed, chances are you are rich, if it feel's "flat" on top you are to lean, I don't think you will have to worry about being too lean, I am going to pull my Dyno-jet kit and try the Keihin jets also and I have the 142/145 mains BUT I live and ride at 1200-3000 ft. so I may have to go richer if these jets work for 4000 ft and up..... do the air screw's and just ride it for a few ride's and see how it run's, trial and error is the only way to get jetting right, I went into my 650 4 times before I had it dialed in.............