Wow - you totally blew my mind - that is Exactly what it did when it started on fluid, and then very briefly on gasoline...the #4 and 3 pipes got really hot from the exhaust, #2 was hot but not as hot as #4, and #1 was pretty cold.
A little backstory here - I got the bike from an estate sale, it had been stored inside for over two decades. There was an obvious electrical short from the Run switch that melted some of the wires, and I couldn't find a side cover, but other than that it was in great shape. I repaired the wiring, I'm getting 155-165 lbs compression out of each cylinder cold, new coils, wires, plugs etc - but THAT is exactly my problem! Well, that and it won't draw gas through the carbs.
I went through the carbs again yesterday using a pilot fuel-flow chart I found in here, and everything checks out fuel-flow wise; the manifold boots are still soft and without cracks, I have good spark at the points but I had to replace the original screws which stripped out when I tried to make sure the points were adjusted right, and the carbs were absolutely pristine inside when I opened them up for the first time when I got the bike. Seriously, I have Never seen carbs as clean as they were - they were shiny and everything, even the jets, looked new - but I went through them anyway.
The bike has 11 thousand miles on it and appears to have been put in the shop for the electrical short, but then somehow got left behind over 20 years ago in the mechanics shop where I found it, and so now I'm trying to solve my 'won't-run-or-idle' problem.
The tank is off the bike, and is also in almost-new condition inside. I've been adding gas to the carbs through the fuel line with a little squeeze bottle just to see if it will run, and it Did very briefly, but won't stay running; and when it Did run, it did race way up...so when that spring gets replaced, is there a very good chance it will run and idle?
Does the tank need to be on the bike to run? And do all the carbs need to be full before it will run?