Since you bumped it I assume you didn't get the answer you wanted. The only way I ever successfully got rid of ALL the idle fluctuations was to swap out to the Mikuni carbs. It idled absolutely perfect with them. But with the stock carbs the best method seems to be sure they are sync'd properly and have the crossover hose connecting the two.
Mine has slight variations, but only after a lot of riding, it doesn't flucuate sitting still, it's either right around 1100 rpm or up to about 1200 after it gets really warm. It is inherent in the design in the CVK carbs I attribute it to. As well as the temperature/humidity etc, they all contribute to it.
So, if you really dislike it, or it bothers you that much, Give Bill Gately a shout, for about $1500 you can totally eliminate it. I also hear that the $500 CV carbs correct it as well.
