Using parts from old used pieces found at a junkyard and some parts from a home improvement store almost anyone with a little mechanical ability could build this go-kart. And after you're done you will have a grown up toy that will supply hours of thrilling fun.
Find the parts to use so you can make the go-kart. The most important part is an engine of some kind. Ask neighbours or family members to see if they have an old lawnmower you can have, if you don't have one yourself. If you still can’t find one check your local classified ads and you will be able to find one for a very affordable price. You also need a frame or a chassis, like an old shopping trolley or an old bike frame for extra parts and support. Plus you will need the spindle and chain from the bike frame and even the brakes. You also will need some kind of a steering wheel, which you can find at any junkyard or an auto parts store. You could even just use small bike handles. Last, but not least, you will need wheels, like big wheel barrel wheels.
Remove your motor from the lawnmower and remove the blade from the motor driveshaft. There should only be a few very large bolts connecting the motor to the motor mounts. There is a bolt at the bottom of most lawnmower motors that keeps the blade on, though some models are different, either way it is not difficult to remove the blade.
Mount the motor. Take the shopping basket and cut the basket at the base where the bars start to go up towards the basket, leaving you with just the very bottom part of the frame where the wheels are attached. Then attach a piece of plywood the size of the frame or a 2 by 4 in the front and another on the back of the frame attaching them with screws. The wood will provide a surface to sit on and to mount the parts to. Now remove the shopping trolley wheels from the frame and you should now have a base upon which you can build the rest of the petrol go-kart.
When attaching your wheels you need to make sure you mount the rear axle tube level and even and the front axle swivel clamp centred both just one inch from the edge of the wood, so that your cart goes straight. Then slide the rear axle into the tube after you lube it with some motor oil. The rear axle should be the same width as the hole on the tire, while the front axle should be just slightly smaller than the hole on the tire so the rear axle is fixed and the front wheels spin independently. Attach the front wheels by using two screws on each end of the axle on both sides of the tires allowing it to spin without moving off the axle.
Attach the big bicycle sprocket on the rear axle by sliding it on and securing it with a screw or weld before you attach the wheels to the axle. Make sure that the sprocket lines up with the driveshaft of the motor so the chain will be straight. Attach the small bicycle sprocket to the end of the motor shaft using either a screw or a weld.
Attach the motor to the frame. Simply line up the motor on top of the rear axle and make sure that the sprocket on the motor lines up with the sprocket on the axle then attach the motor to the plywood or 2 by 4 using bolts.
Take the bicycle chain and tighten it around the two sprockets making it very snug so that there is not much give and then tighten the chain back up. Your petrol go-kart should start and drive at this time, but you still won’t be able to steer.
Figure out where you will sit. Somewhere in between your legs you will need a place in the wood near your ankles for a hole that will allow your steering shaft to go through so you can attach it to the plywood using a loose pipe clamp. Then you must attach a wire or very strong string from the bottom of the steering shaft using a bolt. Attach the other ends of the wire to either end of the front steering axle, giving you the ability to turn your go-kart.
Add a brake, the easiest being a simple friction brake. Take a piece of wood like a 1 by 2 and cut it to be around three feet long. You then put only 1 screw in the piece of wood and attach it to the side of your go-kart into the plywood loosely, somewhere near your side and in a position that it is comfortable for you to pull on. Make sure you leave enough of the stick under the frame so that when you pull the stick back it rubs against the ground and then creates friction and makes you stop. Attach a seat or a pillow and you are ready to go.
Take your time and measure everything to make sure it fits correctly. Don't be afraid to use the hammer to manipulate things into doing what you want them to do.
Ride your petrol go-kart at your own risk. And always wear a helmet.