Step 1.

Inspect the bore. Only severely damaged bores require honing, most will be fine with a new piston and rings. Sometimes the exhaust port has carbon build-up that should be removed before a new piston is installed.

Step 2

Inspect your piston for damage and asses whether a new piston is required; or if just rings will do the job.

Step 3

Remove clips holding in gudgeon pin, then gently hammer out gudgeon pin.

Step 4

Install new gudgeon pin with new piston on the small end of the con-rod.

Step 5

Then place clips in position as shown; also gently place the new piston and rings in position. The oil expander is no longer supplied, as it is no longer necessary in new or old models. If your kit has the oil expander, place it around the groove for the bottom ring.

Step 6

Give the bore and piston a good clean, making sure no metal flakes or dirt are in the bore. Any dirt and grime will damage the piston quickly, making your work a waste of time.

Step 7 

Flip the mower so the cylinder is vertical, as this helps you get the piston in easily. Now use your piston ring compressor, or screwdriver as shown in the video, being careful to make sure the rings line up with the locking clips.

Step 8

Once the piston is in the bore you may place the mower in the normal horizontal position and reinstall the crank pin. You will need to stuff the bore with a rag to stop the piston moving.

Step 9 

Next you need to prepare the cylinder and head; so that they are clean, flat and smooth, ready for a new head gasket. This is demonstrated in another video specifically concentrating on head gaskets.

Step 10

Once the surfaces are prepared you may install the head gasket and tighten the head down. The head bolts need to be tightened quite well, but not too much. The specification if you have a torque wrench is 13.5-16 Nm or 10-12 f/lbs.

Step 11

Next you can tighten down the starter, making sure the seal is intact. The torque settings are the same for these bolts.

Step 12

Then replace the top cover and connect the fuel line.