How to Rebuild a 2-Stroke Motor Motorcycle
Two-stroke motors do not have as many moving parts as four-stroke motors. They also don't have a complex valve train. In fact, a two-stroke motor is essentially just a duct. Whenever they are fast revving they tend to damage their top-ends more frequently.
Things That You Will Need
- A motorcycle lift
- A shop manual
- Mechanic's tools
- A gasket kit
- Find a clean, well-lit workspace that has a motorcycle lift.
- Remove the seat, fuel line and fuel tank.
- Remove the spark plug wire.
- Loosen the intake manifold clamp.
- Remove the carburetor.
- Secure the throttle cable so that it will not get in your way.
- Remove the air box.
- Unscrew the head bolts.
- Remove the bolts that are located at the base of the cylinder.
- Remove the cylinder.
- Remove the piston and the wrist pin.
- Inspect the cylinder wall, head, piston, rings and wrist-clips.
- Decide what you need to replace and what you need to repair.
- Determine whether your cylinder is plated with Nikasil. If so, you will need to have a mechanic do the cylinder clean up work for you. Otherwise, you can hone the cylinder yourself.
- Take the head to a machinist to have any damage repaired.
- Purchase a new piston, rings and wrist-pins.
- Install the new piston, wrist-pin and circlips.
- Coat the piston with motor oil.
- Install the rings with a ring compression tool.
- Install a new gasket onto a clean base surface.
- Coat the piston with oil.
- Slide the fresh cylinder over the piston and rings.
- Release the ring compression tool.
- Remove the remnants of the old head gasket.
- Replace the head gasket.
- Reattach the fresh head to the cylinder.
- Use a torque wrench to bolt the head bolts to factory specs.
- Reassemble the carburetor, coolant hoses and air box.
- Replace the fuel tank and seat.
- Refill the coolant.
- Replace the spark plug cable and any other parts that you removed.
- Start the bike and pay attention to how it runs and sounds.