GP Piston and Ring Development

Project details

Whilst working with port configurations on ‘GP type’ 250cc 2 stroke engines, we came up against limitations¬†in exhaust port blowdown area. We solved this by developing a novel piston, with the piston ring retained to a maximum excursion by the ring and ring groove design. This enabled the port to be designed with no bridge.

There were a number of difficult technical challenges to overcome in the piston, ring and port itself with this design. It was important to control the excursion carefully both for operational longevity and manufacturability. Shown here are photos of the initial prototype, based on a modified standard 54mm piston.

This project culminated in a patent.