I have owned this 4-stroke for almost 2 years, with same intermittent problem: one or two of the 4 carbs will load up and drop for no apparant reason. Yamaha has been of little or no help, dispite this being under warranty. We have had very competant shops check all the obvious: carb sync, coils, dashpot settings, etc. I am beginning to think this is something off the wall. Any suggestions greatly appreciated. <br />C.W.Oakes