Hello all. Have put about 400 miles on my "new" 1982 Yamaha Maxim 750 and she is a strong runner. My bike starts fine with choke when needed idling up to 3k. It also starts fine when it is warm without choke. It goes from idle to redline without a hitch. Problem is, as the bike gets warm the idle goes up to about 3k (should be about 1k). If I let the clutch out a bit it drops, but when I have the clutch in all the way it is 2k too high. So I have run some seafoam through 2 tanks...The second bit I ran through today.....here's what happened: I was riding down a 2-lane hwy after work this morning (after putting in more seafoam), pulled over to the shoulder after realizing that I had a loose mirror. No problems, bike is running like always, idle high, no other issues. I remembered reading on a forum that someone recommended to one of the posters who also had the high idle on warmup problem to disconnect the vaccum line from the petcock. So I did this while I was stopped. The sound of the bike immediately changed and after several (30 or so) seconds the rpms dropped down to 1k! I was ecstatic since this problem has plagued me for a while (and I reeeaaaaly don't want to tear down the carbs if I can help it). So here it is, idling perfect, I revved it up to 5-6k and then cut throttle to see if it would come back down....took a second or 2 but it dropped down fine. I pull a U-turn to head back home feeling like king **** and then my bike starts surging on me.....after about 10 seconds of this the bike gets awfully quiet (died). I am positive I ran out of fuel on the primary, read below. Switched to reserve and cranked it right up. Not wanting to be stranded I made a beeline for home figuring I could monkey with it there. I rode around the neighborhood and unplugged the vent line again and it started to backfire (which it didn't do before) so I reconnected it and it stopped. Man I am stumped! I am not very mechanically savvy. I don't know if the initial smooth idling I got earlier was from the seafoam cleaning out the idle jets, or from the vent line being disconnected. I am pretty sure the engine was surging and died due to low fuel, I totally forgot that when I filled up last night I didn't fill it up totally full, so even though the trip meter indicated I should be ok, I didn't take into account the less than full tank, lol. Long story short, do you guys think disconnecting the vent hose made it idle good or is the seafoam more likely.....I think it was the vent hose, but I don't know.