[sanddrag]

I think square tubing is an exellent choice. It should be very easy to work with. Do you have an abrasive blade chop saw? With steel tubing, you will probably be able to go with thin wall to save weight.

Building a gokart is extremely educational. There is little safety risk as long as you know how to operate the tools you are using and wear a helmet when you are riding. Also, don't ride on busy streets (you're probably not supposed to ride on any streets).

Everyone says get a honda engine but I wouldn't rule out a Briggs & Stratton engine like this one http://cgi.ebay.com/ws/eBayISAPI.dll...3585 503&rd=1 They are extremely reliable. Buying on eBay would cost a lot to ship unless it is local but I would try to get a used lawn or construction equipment machine of some sort (I think maybe water pumps use them too) to pull the engine from.