The one-cylinder Go Kart engine is simple to work on, only requiring simple hand tools. But the repair work must be precise due to the tight tolerances the 65 to 250cc engines must operate within. These types of engines are designed to run at high rpm for prolonged sessions, forcing many parts like the piston, head gasket, spark plug, cam and even the walls of the cylinder to wear quickly. Troubleshooting the repair will require a sound understanding of engine dynamics -- the cause and symptoms of engine issues.
Evaluate what symptoms your engine is displaying. Is it backfiring? Is it running rough? Overheating? Do you hear any metal on metal clunking? Do you feel a reduction in power or top end speed? Identify the symptoms before you tear into the motor.
Pull the spark plug cap off with your hand and unbolt the spark plug from the head with a deep socket wrench. (most socket sets come with a special socket, including a rubber bushing, specifically for spark plug removal). Inspect the spark plug for black charring that would indicate it has been fouled. Replace this part first if backfiring is your issue.
Remove the drain plug off the bottom of the crank case and allow the oil to drain. Use an allen wrench or socket set to remove covers like the crank case cover, head gasket and water pump assembly. Once inside these areas, you can inspect these areas for any broken or failing parts and repair as necessary. Do this if you hear metal on metal, the engine overheats, or the engine has seized.
Cover parts like the cam shaft, piston or transmission gears in oil before inserting them into their place within the motor. This is an important part of any repair, as new parts will need immediate lubrication.
Use gasket sealant when re-assembling any parts that will meet "metal to metal" and will be subject to leaking such as the gear case cover, engine block or head gasket. Squeeze a bead of sealant along the rim of connection point and press the connection together.
Tighten all engine bolts with a thread locking liquid. This will prevent any vibrations from backing out vital screws and bolts.
Use wire cutters to work with the ignition wires, and use plastic zip ties at tight intervals to secure the wiring and hoses to the frame -- away from heated or moving parts. Working with the ignition may be necessary if the engine runs rough.
Use pliers to peel off hose clamps. This will allow you to access things like the carburetor ports, fuel filter and water pump. This will be important if the water pump or fuel filter need to be replaced.
