Right! In that case, that pot is a Kev's fuel mod. The idea is that you adjust that knob in either direction until you get a satisfactory smooth ride. There is no such a thing as a "zero" settings to go back to but if you follow the steps below you can adjust the Kev Mod to the best of its capacity.

However before you adjust the knob, please make sure of the following:

1) correct chain tension - chain is not too slack / taught
2) tickover or idleing speed is kept between 1450 - 1500 rpm to learn how to adjust the tickover please follow these steps:

Switch off Engine Run switch, switch OFF Key switch.

1/ Press both SELECT & RESET buttons and then switch ON Key switch, keep SELECT & RESET buttons pressed for at least 8 seconds. Display then changes to "DIAG". Release SELECT & RESET buttons.

2/ Press the SELECT button once until CO displays, press SELECT & RESET buttons again & hold, CO1 should display.

3/ Once selected CO1, switch on the kill switch & crank the motor. Once started the rev counter should be in the right side of the LCD screen.

Once you have the diag mode on the screen locate a screw which is on the left hand side of your throttle body

Turn this screw clockwise & this will increase the idle speed. I would set your idle once the engine is warm to around the 1500rpm mark

Once you are happy that your tickover sits regularly at 1500rpm, and that your chain has the correct tension, with the engine warm go for a ride and start with the knob all the way off and see how the bike behaves at low rpm's if it judders or stalls then you increase the knob setting a notch or two. Try again, test ride it and see if it improves. Keep turning the knob until the bike has the smoothest ride possible, but remember do not do this test before the tickover and the chain slack are set correctly.