Stupid, STUPID me....Ok, I finally realized, after 4 months of riding (and a yr and a half of owning) the 550 and after doing numerous other fixes that didn't help and only led to more problems, WHY my gas tank would create a vacuum lock...Plugged vent hole IN THE GAS CAP. I was always told it was on the tank (the vent hold that is, and this wasn't from anyone here), and due to me not searching, it took me this long to find it when I got another tank and cap from a friend of mine. This one slips on much easier, no fight to make it seal, so I'm pretty damn sure that that was the problem...Son of a...don't you hate it when you do that? Oh well, its led me to buy a new petcock and replace all the float needles in the bike, which were all probably needed, petcock especially (no more rigged up leaky brass valve), so it wasn't all a total loss.
