This is the Werks Racing non-pull start Team Line .21 Off-Road 3-Port Racing Engine with SG (pilot) Crankshaft.

SPECS:
Weight: 8.1oz (230g)
Displacement: .21 cu in (3.4cc)
Horsepower: 2.40hp @ 34,500RPM
Cylinder Bore: 0.65" (16.48mm)
Stroke: 0.64" (16.3mm)
Carb Bore: 0.31" (8mm)
Crankshaft Bore: 0.39" (10mm)
Crankshaft Diameter: 0.56" (14.2mm)