wrist pin buttons

How do the wrist pin buttons work instead of the clips?

They just slot in the piston either side of the pin and stop the pin from sliding sideways and gouging the liner.
They are usually teflon although some early ones (russ collins etc) were aluminium.
Really meant for drag strip/race use for ease and speed of dissasembly and re-use.
If used for prolonged running hours when say used in a road bike, they will leave a polished vertical strip on the liner wall.

MTC Piston kits come with wrist pin buttons. I think they are the way to go.

Think about this..
If they were such a great advance,
Why don't all new fast NEW bikes come stock with them?

For RACE engines ONLY.

PS how long did your last new Teflon frying pan last?

When we set up a button, pin assembly, we run it .020" less than the bore, so that the buttons do not constantly ride the bore. They will last a very long time and are at home in street motors as race motors.

On some applications where the piston is a slipper design, or severely side milled, we make aluminum buttons that have a diameter that press fits into the pin, thereby creating aluminum tipped pins. These just slip in the piston and the cylinder goes on.

During tear downs service, they just slide out.

APE Jay wrote: When we set up a button, pin assembly, we run it .020" less than the bore, so that the buttons do not constantly ride the bore. They will last a very long time and are at home in street motors as race motors.

On some applications where the piston is a slipper design, or severely side milled, we make aluminum buttons that have a diameter that press fits into the pin, thereby creating aluminum tipped pins. These just slip in the piston and the cylinder goes on.

During tear downs service, they just slide out.

Thanks Jay,
I learn something new everyday.