new 3W 106 is here
The 106 motor is not a bored out version of the 100.
Both motors use the same 44 mm piston diameter.
The stroke of the 100 (actually 97cc), is 32 mm.
The stroke of the 106 motor is 35 mm.
The 106 uses a different crankshaft.
This info is not from either the Cactus Aviation or Aircraft International website. It's based on the engine dimensions from 3w modellmotoren - from the 212cc 4-cylinder.