Hey guys- this is one is on a Mojave with cycleworks .380 cams and an open airbox. At 7,200 feet elevation I have the jet needle clip at #1, a #45 Pilot/ Slow jet and a 146 main. Jest about everything is great, robust top end, 2nd gear holeshots are tops but where it stumbles is when I wick the throttle open as in a fashion to loft the front end over a rut. That stumble has been helped a little with turning in the fuel/ air screw at the bottom of the carb. I can only think either going to a #48 Polit and/ or adding a shim to the jet needle.....................
Thanks

 

If it was helped by turning the screw in, your leaning it out. At that altitude IMO a #45 is too rich. I would suggest going to a #42 pilot and see where that takes you.

 

THanks spray- thing is that I came from a #42, and had to turn the srew in even more. I'm starting to go in circles more and more it seems. Also found out that a good but restrictive air filter can really sway things, not that that matters at this point as I'm kinda working my way back to where I was. As to the air screw, which I understand is actually a fuel screw on a 4- stroke richens the mix turning in. Argh, gotta review the facts. Thanks- I'll let ya know what cooks up..............

Edit;
OK- makin' some sense outta all this here; fuel mixture screw meters gas after it has been mixed with air. Turning it out lets more fuel into the engine and richens the mixture (just the opposite of the air screw). Screwing the fuel mixture screw in leans the jetting.
A little counter- intuitve thinking here. I know the #42 Pilot is the hallowed jet size, and I'll go back to that and try clip #2 on the jet needle instead...............

 

You're heading in the right direction. Most people don't realize that the fuel screw is the opposite of a 2 stroke air screw. Turing an air screw in richens it, but a fuel screw going in leans it. Your biggest obstacle is the altitude. If the #42 doesn't work, try a #40 instead. A #42 worked perfect for me at 900 ft, but with you being 6,300 ft above I think a better pilot is the #40.

 

Makes sense, I think I have a #38 in the jet box. Thing is- I'm gonna try and sell the quad to my boss, or his son really, and they live in Stanley which is 6,200 feet. I wouldn't think that 1,000ft in altitude change would amke a perceptible difference, depending on your experience. But if the facts are otherwise please say so.

 

I don't think it would make a noticeable difference at 6200 ft and where you are. As long as you get it as close as you can, it'll be fine at their altitude.