Things You'll Need
Power equipment engine (lawnmower, etc.)
Wheels and tires adequate for speed
Chain and sprockets
Using a shopping cart to fabricate into a go-cart takes ingenuity and skill. The parts are easy to come by, and when crafted together can make a shopping cart attain quick speeds in seconds. The average backyard mechanic will spend about a week on this project.
Replace the standard shopping cart wheels with the heavy-duty rubber ones, and assemble brakes. This will involve removing the stock wheels and welding in hubs, or using an axle that has wheels attached and spins freely. A riding lawnmower is an excellent vehicle to harvest parts from, as the steering assembly can be hard to fabricate from scratch. The stock mount points can be used for the rear wheel axle mount, if bicycle parts are used such as wheels, brakes, and frame sections. Most complete axles manufactured for riding power equipment will have a braking system attached or available. Imagination is key when deciding how to attach the wheels and guide the steering, as these can be arranged in numerous ways that will affect handling and braking. Extreme wheelies can be possible, and the speed and power should be taken into consideration.
Attach the power and drive system. Rear wheel power is simple and effective, and is the easiest to connect. A small engine, over one horsepower but less than ten, will drive a side-mounted chain to the rear axle or drive wheel sprocket, depending on the design. Having twin sprocket-driven rear wheels without an axle will enable the use of two motors, one on each wheel, linked to the same accelerator cable. Weld the engine chassis to a thick portion of the shopping cart frame, if possible. A bolted frame section can be grafted onto the chassis of the engine, and then welded. As long as the engine can withstand the forces of driving the axle sprocket and stay in place, then it will function well. Most lawnmower engines will include a length of cable that can be positioned within reach of the cart operator, and some of those will have a "dead-man" switch for stopping the motor.
Connect accessories, like battery powered lighting, or add paint. Some more powerful carts will have the possibility of driving a strong alternator, which could power any number of entertaining devices for as long as there is fuel.
Wear safety equipment when welding.
Use caution when operating the shopping cart go-cart, as it's center of balance is high and can tip over.