I finally worked up the courage to do the white spacer carb modification. No problems other than a slightly stripped top carburetor screw. I also drilled out the brass plug on the idle mixture screw. It was set to about 1 turn. I played around a bit and found very little difference from 1 to 3 turns out and then it started to sound a bit weak. I left it at about 2 turns out but to be honest there was very little difference. I then backed off the idle speed slightly.

Wow, what a difference, much better running in first and second gear accelerations and when the engine is cold. However, my question is if others have noted very little difference when adjusting that idle mixture screw??  Any comments appreciated.

Larry Gagnon

Basically what You should do is so called "idle drop test",
Years ago Honda was recommending this way to adj. the idle screw.
What You do, You start with the basic setting ~1.5 turns out. You screw the pilot screw in until the RPMs start going down. After that You start going back. The RPMs will go up and then they will start to drop. You count the turns that You went out, devide in 2 and set the screw right in the middle.
All the adjustments are done with the engine - operating hot.
Like a rule if You blip the trottle and the RPMs go up and they drop below the normal idle RPMs before they return where they are supposed to be or if the bike dies- this is rich condition, so You just give it a 1/4 turn in and try again