I am wrong about the engine. It has 270cc displacement. Surprising! I used the displacement calculator on Spicer webpage to verify it (
https://spicerparts.com/calculators/...ent-calculator).
Here are specs on the engine (more than 18hp, stock!):
Bore & Stroke (mm): 70.2x70
Compression Ratio: 9.2:1
Cylinders: 1
Displacement (ml): 270.8
Engine Type: oil-cooled 4-stroke
Max power (kw/(r/min)): 13.5Kw/8000r/min
Max Torque (N.m/(r/min)): 19.5N.m/5500±500r/min