The Harley-Davidson Topper was the only motor scooter that the Harley-Davidson Motor Company ever produced. Wikipedia
Bore / stroke: 2.375 in × 2.281 in (60.3 mm × 57.9 mm)
Brakes: Front and rear: 5 in internal expanding drum
Compression ratio: : A: 6.6:1; AH: 8.0:1;
Engine: 10 cu in (164 cc) 2-stroke single-cylinder engine with reed valve
Top speed: 46 mph (74 km/h)
Transmission: continuously variable transmission, between 18:1 and 6:1