Help with a Yamaha

OK. Here are the final results. I pretty much took everyones suggestions. I did not remove the carbs, although I do have access to a syncronizer. Anyone who knows me, knows I will always start at the very basics. It pays off about 99 per cent of the time. So, I checked coils, OK, checked timing, OK, checked battery, OK, new plugs, dumped fuel tank, and filled with about a gallon of fuel and one whole can of seafoam. One part of the fuel line was a little questionable so I replaced all the fuel and vacuum lines. I took off the air cleaners and sprayed all the carbs clean and any of the orrifices I could see, and backsprayed the two vent tubes (?). I took the fuel pump out and cleaned it with carb cleaner. I shot carb cleaner back into the tank at the valve, through the vacuum and fuel openings. Then I checked the opperation of the throttle and choke. When I got it all together I started it. It ran a little ratty for a few seconds, and then it commenced to doing all the same things again. Well, needless to say I was somewhat taken aback. If it wasn't my first attempt at a jap bike I'd a burned it to the ground. So I went over to the shelf and got a can of ether. I slowly started opening the throttle so it wouldn't die and just sprayed the ether right at the air cleaners. It died. Not to be outdone I started it and began bringing it up to speed and sprayed just a little ether at it. It gained a litle rpm's without dying. Then, get this, it instantly reved to about 12 grand. I thought it was gonna explode. So whatever. It goes down the road good. Just a tad sluggish, and I am hoping that will improve once it gets a blast down the interstate. So thanks to all for great suggestions, and I'm off to get my town and country cooling fans spinning again.