Mark took a head from a Hercules Bristol bomber aircraft (3 liter, sleeve valve) and designed his own bottom end and gearbox to power his chopper (thanks Kim!)

2800cc sleeve valve cylinder from a radial aircraft engine, fitted into bespoke homemade crank case, and cradled in a frame and forks made by a Raw Steel Choppers Ltd.

Video of the engine running for the 1st time: https://www.facebook.com/reel/1157997425453559

https://rawsteelchoppers.co.uk/projects-%26-news/f/project-hercules

https://www.youtube.com/@StoneEng/videos