Built around Kawasaki's naked motorcycle platform, the 1990 Kawasaki ZR 550B Zephyr utilizes a 553 cc (33.7 cu in) oil & air-cooled in-line four, four-stroke layout. In factory specification, peak output is rated at 50 HP (36.5 kW) at 10,000 rpm while maximum torque reaches 40 Nm (29.5 lb-ft) at 6,000 rpm, transferring power to the rear wheel through a 6-speed gearbox and chain final drive. With a specific output of 90.4 HP per liter and a 4,000 rpm working window between peak torque (6,000 rpm) and peak power (10,000 rpm), the engine character is indicating a tractable, stress-free state of tune focused on everyday usability and broad torque delivery.
On the scales, the ZR 550B Zephyr measures 206 kg (454 lbs) wet (curb), translating to a power-to-weight ratio of 0.24 HP/kg (4.12 kg per horsepower). The 14.98-liter (4 US gal) fuel tank paired with a rated consumption of 4.12 L/100 km provides an estimated theoretical range of roughly 364 km (226 miles) between fill-ups, while factory top speed is listed at 221 km/h (137 mph).
Specific Output
90.4 HP/L
Power-to-Weight
0.24 HP/kg (4.12 kg/HP)
Power Band Window
6,000–10,000 rpm
Theoretical Range
~364 km (226 mi)
Engine
Displacement553.0 ccm (33.74 cubic inches)
Engine TypeIn-line four, four-stroke
Engine DetailsIn-line four, four-stroke
Power50.0 HP (36.5 kW)) @ 10000 RPM
Torque40.0 Nm (4.1 kgf-m or 29.5 ft.lbs) @ 6000 RPM
Compression9.5:1
Bore x Stroke58.0 x 52.4 mm (2.3 x 2.1 inches)
Valves/Cylinder2
Fuel SystemCarburettor
Fuel ControlDouble Overhead Cams/Twin Cam (DOHC)
IgnitionStarting
LubricationWet Sump
CoolingOil & air
Max RPM10200
Transmission
Gearbox6-speed
Final DriveChain (final drive)
ClutchWet Plate
Performance
Top Speed220.5 km/h (137.0 mph)
0-400m13.79 seconds
Fuel Consumption4.12 litres/100 km (24.3 km/l or 57.09 mpg)
Greenhouse Gases95.6 CO2 g/km. (CO2 - Carbon dioxide emission)
ExhaustSingle Stainless Steel pipe
Chassis
Front Suspension39mm Telescopic forks
Rear SuspensionDual Kayaba shocks with preload and rebound adjustments
Wheels & Brakes
Front Tyre110/80-17
Rear Tyre140/70-18
Front BrakesDouble disc. Two-piston calipers.
Front Brake Ø300 mm (11.8 inches)
Rear BrakesSingle disc. Single-piston caliper.
Rear Brake Ø245 mm (9.6 inches)
Dimensions & Weight
Dry Weight179.0 kg (394.6 pounds)
Weight incl.206.0 kg (454.2 pounds)
Power/Weight0.2793 HP/kg
Fuel Capacity14.98 litres (3.96 US gallons)
Other
StarterElectric
Notes
Area code US,CAL. Frame range JKAZRFB1_LA 000001 - JKAZRFB1_LA 004000. Engine range KZ550DE 060001 - KZ550DE 999999.
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.
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.
Suspension
Suspension details can matter for comfort, road feel and long-distance riding.
Transmission
Transmission and final drive affect maintenance, smoothness and everyday usability.
