PIONEER 550:
YEAR INTRODUCED: 1964
YEAR DISCONTINUED: 1968
ENGINE DISPLACEMENT: 5.45 cu. in. (89cc)
NUMBER OF CYLINDERS: 1
CYLINDER BORE: 2.25 in. (57mm)
PISTON STROKE: 1.375 in. (35mm)
CYLINDER TYPE: Aluminum with cast iron sleeve
INTAKE METHOD: Piston ported
had 8 tooth sprocket as standard, rubber grip on front handle, improved porting for 11% more power over 450, non slip grip on rear handle.