Thanks for the reply Pe I appretiate it.

From your website

"The engine is based on the 116cc crankcase, and the short stroke 80cc cylinder/piston design, with even further reduced stroke for most compact packaging.

A further devellopment of the very powerful 116cc along the shorter stroke philosophy, this engine is targeted at about 13 hp open exhaust sustained power, not useless peak peek readings which may exceed sustained power by 20%."

That would indicate a common crank case, but possible a different crank shaft? When you say that they have a common "prop central bolt" are you refering to the crank shaft? If that is common as well then I think what we're looking at is a 116 with bigger pistons. Information on evolutionengines.com indicates a common carb/reed system (makes sense with a common crank case).

Also the dimensional drawings show that the plug hole to plug hole distance is the same for the 116 and 152 so that is good evidence although not proof that the crank is the same......... I'm very curious about this.