I see that folks are having problems adjusting the idle circuit on the GP 42 carburetor.On the GP 42 the carb has a bleed port that is activated when the barrel is shut. To adjust the idle circuit to make the motor richer you screw the idle mixture screw clockwise which turns it in. This closes down the bleed port allowingless air in and makes the mixture more rich. So to lean it out turn the sidle mixture screw out which allows more air into the mixture making it more lean.

My next post will cover what can be done to a stock motor and still be called stock.