Well i am having a hard time finding the exact one that I use to use, but it looked just like this one. They have cheaper one on the web site that is around $25 that doesn't show a pictures, but the one I used looked pretty much just like this one.
http://www.jbugs.com/store/merchant....Category_Code=
Here is a more expensive one from JC whitney that would work well on Bikes. I keep saying I am going to order one of these, but i never have. The air tubing things seemed to work well, though much slower than probably having one of these gauges. Might not be quite as accurite as these guages either.
http://www.jcwhitney.com/CARBURETOR-...4252_10111.jcw
Static.