Hi All,  
I did the kn filter/ sportser muffler mods and am working out the jetting.  I'm at 2500ft in hot dry tucson az and the standard jetting mods (152main/half spacer)aren't working for me  (smoking, stumbling, fouling!).  I'm back to stock jetting/spacing now and I think it is better but not right.  
The really odd thing is the idle mix screw.  I get a better idle the more I turn it in!  Full closed is the highest and smoothest, should kill the engine shouldn't it?  With stock jetting I get best idle between 3/4 out and full closed, past 1 1/4 out it will barely run.
 I've cleaned and blown out all passages and jets, slide is smooth and diaphram is good.  choke is working and the small decel valve and diaphram are good too.
 Should a fully closed idle mix screw kill the engine?  I can't figure what I have wrong.  Anyone else had a similar problem? Any ideas?
Thanks
Bob

Check the float level, & make sure you put the washer under the main jet when you changed it.
                                  Gramps

Just to be sure, you are talking about the idle mixture (pilot) adjustment on the right side of the carb... not the idle speed on the left side of the bike.  Is that correct?

I have the stock carb w/ stock jetting (145main-52.5pilot).  Checked for main jet washer and float level is about 3/8" from top of bowl.  Yes, I'm referring to the idle mixture screw on the right (muffler) side of the bike.
There is also a slight hitch when running at a steady speed under about 50mph.  Is that that the pilot jet?

Serowbot wrote on 12/31/69 at 16:00:05:

Pilot Jet & Slow Mixture Screw- 0 -> 1/8 throttle

Needle & Needle Jet -  1/8 -> 3/4 throttle

Main Jet -  3/4 -> full throttle