How to replace a piston

[Pappy]

One circlip is installed in the piston to act as a stop for the wrist pin

[Pappy]

The cylinder should be wiped down prior to reinstalling the piston. The instruction manual for the ATV or from the piston manufacture should tell you what oil to use. Eric prefers using 2 stroke oil as it burns away clean will provide the needed lubrication during assembly.

[Pappy]

Carefully the new piston and rings are slid into the cylinder, taking care to make sure that each ring goes easily into the bore. Take your time here, no sense in rushing and not being careful.

[Pappy]

A helper helps hold the cylinder and then the timing chain as its fed through the cylinder.

[Pappy]

The piston is guided onto the rod and the wrist pin is installed. Ive seen this done both ways, with the piston installed then the cylinder installed. You have to go with what work for you especially if its an in frame project as room can be at a premium when you have the frame in your way.

[Pappy]

Now the second circlip is installed to lock in the wrist pin

[Pappy]

Making sure that everying is in place, a gentle tap around the cylinder with a rubber mallet will help seat it

[Pappy]

The new piston is now installed and the top end is ready for the final stages of assembly

[Pappy]

In every step of this process, parts should be cleaned and inspected for wear and damage.

[Pappy]

The timing chain guide is reinstalled by inserting it into the slots inside the machined recesses.