I've never done that, but wouldn't adjusting the idle speed to 2300rpm take the carbs off the mixture circuit and the mixture screws wouldn't have any effect? My Solex books speak much the same as to a Weber tuning. If you have to turn the mix screws out more than "x" turns, then one needs to change the pilot (idle) jetting.
The PHHs on my 2000CS behaved similar to Larry's here... one size pilot jetting would idle very nicely and within spec to the number of turns out on the mix screws, but they would lean pop at part throttle. I put in the next size pilot jets and turned the mix screws in and made it happy.
I also believe today's fuels don't allow us to jet our carbs like manuals written 40 years ago might suggest... My guess is if Larry installs the next size up pilot jet, he may solve his problem.
One last question I have for Larry... the engine is completely warmed up and it still spits? All jetting and tuning should be performed on an engine at operating temperature.