As you wants to Built a Goa Kart let me tell you that First thing you you need to do is to gather all the parts, the Parts that May used to Built the Go Kart is as follow

Materials you will need:

25 or 30mm Square Steel
Aluminum Sheet 1.6mm thick
19mm and 25mm Steel Tubing
25mm solid
30mm bright solid (If you want to make your rear axle)
13mm tube or pipe.
lots of 6mm and 8mm nuts and bolts
Axel
30mm hubs
Sprocket or disc carrier
sprockets chain and clutch
Mechanical Brake Caliper With Brake Pads & Cable
Go Kart Brake Disc
Self Align Pillow Block Bearing 30mm
4 Wheels
4 Tires Steering Wheel
Seat
Engine


Parts you will need:

Tools we used.

Drill press
Metal Lathe
Tap and die
Hack saw
Grinder
MIG welder
Cordless drill
Roller


Procedure to Built the GO Kart