I have a 1982 XJ550 that I've been working on for a little while. When I first got it, it would rev too low and die if i didn't constantly give it some throttle. I opened up the carbs and cleaned them. When I reinstalled, the bike ran well. However, the idle was pretty high at 1500rpm. Now, if I turn it on, it will start out at about 1000 and slowly make its way up until it's at about 5000rpm and won't lower until it cools. I have tried adjusting the idle speed screw to no avail. I'm right in the middle of adjusting the valves, but I wouldn't think that would cause this. The caps on the little metal nipples for synching the carbs are pretty hard, and I've read that can cause vacuum leaks. I also left the carbs together and dipped them when cleaning, which I have read can damage some seals between the carbs. Anyone have advice on how to fix this idle?