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How to Rebuild a KT 100 Kart Engine

The KT 100 is a 100 cc, two-cycle engine manufactured by Yamaha primarily used on go-karts for racing. This air-cooled engine runs on an oil-gas fuel mixture and features a Walboro carburetor. When engine parts wear out, the engine needs to be systematically taken apart, inspected and cleaned, and damaged parts are replaced with new ones. It takes approximately three hours to rebuild a KT 100 go-kart motor.

Things You'll Need

Spark-plug wrench
Hex wrench
Phillips screwdriver
Socket set
New piston and rod assembly
New cam shaft (if needed)
Wire brush
Spray engine cleaner

Instructions

- 1
  Remove the spark plug wire from the plug, and then remove the spark plug with a spark-plug wrench.
- 2
  Remove the carburetor from the lower left-hand side of the engine with a hex wrench. Remove the fuel lines from the carburetor, using a Phillips screwdriver.
- 3
  Remove the bolts holding the engine to the go-kart frame with the socket set, and move the engine to a work bench.
- 4
  Remove the engine head with the hex wrench, and then separate the block from the motor crank case with the socket set.
- 5
  Remove the rod assembly and piston bearing with the hex wrench. Once the rod assembly is loose, slip the piston and rod through the top of the head. Inspect the parts for wear, and replace with new ones if damaged or worn.
- 6
  Remove, from the gear box, the bolt that holds the cam shaft, using the hex wrench. Remove the cam shaft and inspect it for wear. Replace it if worn or damaged.
- 7
  Clean the chambers of the engine with a wire brush and liquid engine cleaner.
- 8
  Reattach the cam shaft to the crank case, using the hex wrench.
- 9
  Slip the new piston-and-rod assembly into place. Connect the bearing to the rod with the hex wrench
- 10
  Attach the block to the motor crank case with the socket set. Set the engine head back into place, and secure it with the hex wrench.
- 11
  Lift the engine and mount it back onto the go-kart frame by tightening the engine-mounting bolts with the socket set.
- 12
  Attach the carburetor back onto the engine and reconnect the fuel line.
- 13
  Screw the spark plug back in and tighten it with the spark-plug wrench. Replace the spark-plug wire.

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