The goal of building a go-kart is to build it as light as possible, but still build it strong enough to take abuse. This can be hard to do, and some engineering background could be helpful. All of my go-kart frame is built from Carbon Mild steel. This steal is lighter and stronger then plain steal. I used 1 1 /2” .096 tick for most of my frame, and .065 for A-arms. Now when I think about it 1 1 /2” .096 is over kill, and probably a bit heavy. But at the time I was buying steel I was thinking since I am placing a larger engine I might need 1 1/ 2”, now looking back I think it is a bit much. You should look in your local yellow pages for steel and metal suppliers, call around, they all have different prices, and some only sell to companies. Majority of steel is sold in 20 fool long peaces, so plan accordingly (transport). You could do some research and find what type would work for you. I decided to go with mild steel because of its price, and durability. Other possibility is Cron-Molly, but it is not cheap, and it needs a special technique to weld it.

You need to decide what type of steal you are planning to use, round or square.

Pipe (round): I used a pipe since I like the way pipe looks on a go-kart. But round steel is too hard to work with. It’s a pain to join peaces [picture] (might need a tool “moncher” about $80), and you will need a bender to bend it as well. Benders are not cheap over $150. If you can get your hands on one then go with pipe style steel, if not think hard if it’s really worth it to use round steel.

Square: It can be cheaper, and it is much easer to work with. But some people don’t like the way it looks. You decide.
If you still want round steel you should consider making it easy on you, and build a main frame with square and then rest, more visible parts, with round steel. If I was to do this all over again this is the way I would do it.

Most important: make sure you weld frame well. Few times welds have given way from abuse, and hard rides. So make sure you take your time and make the frame strong, and supported on several points. After first few rides carefully look over your welds and make sure that they are all ok.