Here is a picture of my vapor fuel tank carburetor. Compared to a carburetor, this thing is dead simple, starts darn near every time on the first pull, and is very easy to adjust, both speed and fuel mixture. I would highly recommend you start with this to get your engines running, then try building a carburetor later. You can also mix wd40 with your fuel (coleman fuel in my case) and it will lubricate your top engine parts.
I used a glass pimento jar because it's about the right size, you can see the fuel level and see if the engine is drawing fuel by the turbulence in the jar. It's also cheap and readily available, at least in the U.S. for about $1.60, including pimentos! The jar is about 1.5" tall and 2.5" diameter. Dimensions aren't critical and most any container will work.
The 6-32 socket head cap screw is the throttle. Nothing special done to it, it threads down to just past the nipple leading to the fuel line to the engine. It's not real apparent in the picture, but there is a spring under the screw head to keep it from turning due to vibration when the engine is running. The split brass sleeve at the bottom rotates to cover/uncover a hole which controls the air/fuel mixture.
I used 7/32 solid brass rod for both pieces because that's what I had on hand. Quarter inch would probably be better. Both rods were drilled through @ 1/8" and shouldered and threaded @ 10-32 to fasten them to the lid with 10-24 nuts. The nipple which accepts the fuel line is 3/16" and is soft soldered to the vertical piece. It also has a 1/8" hole through the center.
Be careful tightening the nuts when you fasten them to the lid. The tube wall is pretty thin and will break easily.
Here's a video of the fuel tank in action.
[ame=http://www.youtube.com/watch?v=GLzOjL4NIVc]http://www.youtube.com/watch?v=GLzOjL4NIVc[/ame]
Chuck
