'Bought this bike a few weeks back. Fine bike but I noticed that the choke knob rotates and "clicks". So I look in the manual and lo-and-behold it's something the manual briefly describes. Apparently you can adjust it . . . huh? The manual states that the "bypass (starter) system affects air/fuel mixture ratio in the throttle opening range of full close to 3/8 open position. The mixture will become leaner as the dial is turned out counterclockwise to open the system . . . " I just looked at the throttle valve opening chart, you know, the one where it shows what tuning part (jets, etc) does what over the throttle range, and there it is . . . affects things much like the "Slow jet and air screw" does. For those with this carb - do you use this? How is this different than the airscrew? Thanks!