1982 Suzuki GS650G blows white smoke and unsteady idle?

Hi readers,

I found a motorcycle for sale that I am interested in buying. I'm not too worried about owning one, but it seems to be a really good deal. Tell me what you think.

1982 Suzuki GS650G <-- 650cc, 10k redline 4-cylinder bike. It's not a cruiser, more of a standard. 73hp. Could have more power, but definitely ride-able!

Remember: AIR-COOLED, please do not tell me that the white smoke is coolant burning in the cylinders

The seller has the price listed at $650. This is a pretty low price for my area. But it is winter, so motorcycles drop in price.

I called the seller on the phone and talked to him for a little bit about it. The bike only has 17k miles, and the pictures are beautiful. The tank is in great condition and all the plastics seem to be present.

Here's what I'm nervous about: in the ad he said 1) "throttle occasionally unresponsive might be a float issue with one carburetor", then on the phone he said 2) "it blows white smoke for about 3 minutes when it starts up. Never bothered me"

I'm pretty good with mechanics and engines, but I would like the opinions of some fellow Yahoo Answers people, since you guys are pretty good.

What I'm thinking is that the float in one of the carburetors has gotten weak, and it's flooding, causing a rich mixture. This rich mixture is causing the white smoke on start-up. The other possibility I can think of is that moisture is getting in the oil and it's burning off?

This is an AIR-COOLED bike, so it doesn't have coolant. It still does have a head-gasket though.