You basically start them out at 3/4 turn and continue the idle adjustment after setting the base idle at 1200 RPMs. Warm the engine and turn the screw for #1 inwards until the engine starts to slow which will lean the mixture. Then turn it back out 3/8 of a turn. Reset the base idle to 1200 and repeat on # 2. Best of luck.

How do I reset the base idle?

1200 seems low. I thought if it was an aluminum block that the rpm's was supposed to be set at 1650. I've tried 3/4 of a turn and I can't get the mower to run at half throttle. Stupid question when I start the mower cold to adjust the carburetor do I start it at full throttle and then go to half throttle or start it at half throttle. I've been starting at full throttle then going to half for warm up.

The base idle is set with the screw that affects the position of the throttle shaft. The procedure that I gave is out of the service manual and assumes that the carburetor (and engine) is working as it should. If you wish, you may set the base idle higher in then end. If you set it in a fashion that works better for your engine due to other circumstances- I won't tell. The thing to remember is that your idle mix circuits do have an affect as the carb transitions to the load or power circuits. I'd say do the best as you can as it is described above and go from there.