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MotoLibrary Score
32/100Commuter
Power/Weight
0.05 hp/kg
Torque
4 Nm
Engine
49 ccm
Technical Overview
2002 Yamaha YB-1 Four Technical Analysis & Specification Breakdown
Engineered by Yamaha for the classic motorcycle segment, the 2002 Yamaha YB-1 Four relies on a 49 cc (3 cu in) air-cooled single cylinder, four-stroke powerplant. In factory specification, peak output is rated at 4.1 HP (3 kW) at 7,500 rpm while maximum torque reaches 4 Nm (3 lb-ft) at 6,000 rpm, transferring power to the rear wheel through a 4-speed gearbox and chain final drive. Internal engine geometry specifies a bore and stroke of 36.0 x 48.6 mm (1.4 x 1.9 inches) with a 9.5:1 compression ratio.
On the scales, the YB-1 Four measures 83 kg (183 lbs) dry. Rider ergonomics and chassis geometry center around a 745 mm (29.3 in) seat height — giving shorter riders and urban commuters confident flat-foot reach at traffic stops, combined with a 1,190 mm (46.9 in) wheelbase engineered for quick, flickable steering geometry. The 7.2-liter (1.9 US gal) fuel tank supports practical everyday commuting and weekend road stints.
Power Band Window
6,000–7,500 rpm
Standover Height
745 mm (29.3 in)
Engine
Displacement49.0 ccm (2.99 cubic inches)
Engine TypeSingle cylinder, four-stroke
Engine DetailsSingle cylinder, four-stroke
Power4.1 HP (3.0 kW)) @ 7500 RPM
Torque4.0 Nm (0.4 kgf-m or 3.0 ft.lbs) @ 6000 RPM
Compression9.5:1
Bore x Stroke36.0 x 48.6 mm (1.4 x 1.9 inches)
Valves/Cylinder2
Fuel SystemCarburettor
Fuel ControlSingle Overhead Cams (SOHC)
CoolingAir
Transmission
Gearbox4-speed
Final DriveChain (final drive)
Chassis
Wheelbase1190 mm (46.9 inches)
Ground Clearance130 mm (5.1 inches)
Wheels & Brakes
Front BrakesExpanding brake
Rear BrakesExpanding brake
Dimensions & Weight
Dry Weight83.0 kg (183.0 pounds)
Power/Weight0.0494 HP/kg
Seat Height745 mm (29.3 inches) If adjustable, lowest setting.
Use this page to compare this motorcycle by its real specifications, not only by model name. Focus on the details that affect fit, comfort, handling, range and ownership.
Power
Compare engine output with similar motorcycles if acceleration, highway use or two-up riding matters.
Torque
Torque is useful for judging real-world pull, especially for touring, commuting and loaded riding.
Seat Height
Check the seat height against your inseam and riding posture before choosing a motorcycle.
Weight
Compare weight carefully because it affects low-speed handling, parking and confidence.
Fuel Capacity
Fuel capacity helps estimate touring range and how often you may need to stop.
Brakes
Brake setup is worth comparing if you ride in traffic, mountains or with a passenger.
Transmission
Transmission and final drive affect maintenance, smoothness and everyday usability.
