Today, curiosity pursuaded me to pull the choke out 1 click to see how it would run after fully warm. Amazing difference! I expected stalling & sputtering but it totally eliminated all backfiring, ran smoother, quit surging & had a little more power. I've had my gas tank off LOTS off times messing with the jetting & no combination ever worked this well. Currently I've got the pilot screw out 1 1/2 turns, the white spacer is 1/2 width & a 147.5 main jet.  My question is, if I don't end up fouling plugs, would it hurt to just leave the choke out 1 click always? Also, is it a choke or an enrichner? Thanks for any answers.  

The choke is an enrichener, or has an enrichening effect, so I'm not sure what differentiation you are trying to make unless you are looking for something that doesn't restrict air flow & just dumps extra fuel.  It restricts air & also helps vacuum pull more fuel.  It may be fine, depending on your driving style, but it will ultimately restrict performance the farther you open up the throttle because you'll never get the max air flow the carburetor is capable of as long as the choke is partially closed.


Found this which may help:

When the engine is first started, a very rich air/fuel mixture is required because cold fuel vaporizes slowly. The "choke" at the top of the carburetor provides the richer mixture by closing and "choking off" the carburetor's air supply. The choking effect also creates an area of low pressure inside the throat of the carburetor that helps to pull additional fuel through the main metering circuit. At idle there isn't enough air flowing through the venturi to pull fuel through the venturi discharge nozzle. By temporarily choking off the air supply, however, manifold vacuum rather than venturi vacuum helps to draw the extra fuel through the main metering circuit.

You may also just need to bump up on one of the jets. if it preforms poorly on the low end then bump up on the pilot, if it's mid-range you could adjust the needle, and if it's top end bump up the main jet.

I ran mine with the chole out 1 notch for a week. Gas mileage suffered, but man did the bike behave better. Fouled the plug out pretty quick (in combination with the 2 stroke oil).
-WD

Thanks for the input. I tried turning out the pilot screw more but I stripped the groove so I'll order a #55 pilot jet monday. The choke seems to make the biggest difference under 1/2 throttle & by 2/3 throttle it's running well with the choke on or off, so I'm thinking the pilot circuit's a little lean.