You can get the glow engines marked in CC's too... The Webra 10 is a .61. (and that is also the conversion formula for cc to ci.

K&B engines used to be labeled in cc. (sometimes... seemed like they couldn't make up thier mind which to use. )

The reason most Gasoline engines are marked in cc's is.... they started out as conversions from weed-eater (and other small gas power yard tool) engines. And practically all of the gasoline power weed eaters and such are marked in cc's.