Im putting together an air shifter for my 2000 DS so far i have several air/electric solenoids that are 24 volt dozens of shapes and size air cylinder and a bunch of air line i plan on machining an adapter to connect an argon or oxygen regulator to a paintball c02 tank so i can get down to around 120 psi my plan is to have a handle bar mounted upshift button or to make the clutch pull safety swith activate the shifter. any input

 

120psi holy crap thats enough to rip the shifter clean off lol. Unless your planning on having it so the stroke is completely maxed out where the linkage ends.

 

radius of cylinder piston squared X 3.14159 X psi = force
if you are using a tiny cylinder lilke 1/2" in diameter at 120psi that's about 23 pounds force, I think a miniature cylinder around this size would be convenient and trick.
not sure how much force is needed for shifting but I know there's somebody on here with an air shifter that can comment I think? I think maybe THEBOM has some insight

 

Hey thats a cool formula and i do have cylinders ranging from 5/16 to 5/8 and i plan on using a spring to pull the shifter so if something dosnt want to go it wont bend a fork