Positioned in Keeway's sport motorcycle lineup, the 2021 Keeway RKS 125 Sport E4 features a 124.1 cc (7.6 cu in) air-cooled single cylinder, four-stroke configuration. In factory specification, peak output is rated at 11.3 HP (8.2 kW) at 8,750 rpm while maximum torque reaches 9.5 Nm (7 lb-ft) at 7,250 rpm, transferring power to the rear wheel through a 5-speed gearbox and chain final drive. With a specific output of 91.1 HP per liter and a 1,500 rpm working window between peak torque (7,250 rpm) and peak power (8,750 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 RKS 125 Sport E4 measures 136 kg (300 lbs) dry, translating to a power-to-weight ratio of 0.08 HP/kg (12.04 kg per horsepower). Rider ergonomics and chassis geometry center around a 760 mm (29.9 in) seat height — giving shorter riders and urban commuters confident flat-foot reach at traffic stops, combined with a 1,350 mm (53.1 in) wheelbase engineered for quick, flickable steering geometry. The 16-liter (4.2 US gal) fuel tank supports practical everyday commuting and weekend road stints.
Within MotoLibrary's Keeway archive, this model family spans 2 indexed model years from 2019 to 2021, allowing buyers to track year-over-year changes in emissions tuning, weight and equipment.
Specific Output
91.1 HP/L
Power-to-Weight
0.08 HP/kg (12.04 kg/HP)
Power Band Window
7,250–8,750 rpm
Standover Height
760 mm (29.9 in)
Engine
Displacement124.1 ccm (7.57 cubic inches)
Engine TypeSingle cylinder, four-stroke
Power11.3 HP (8.2 kW)) @ 8750 RPM
Torque9.5 Nm (1.0 kgf-m or 7.0 ft.lbs) @ 7250 RPM
Compression10.6:1
Bore x Stroke57.0 x 48.8 mm (2.2 x 1.9 inches)
Valves/Cylinder2
Fuel SystemInjection
Fuel ControlSingle Overhead Cams (SOHC)
IgnitionTLI
LubricationPressure splash
CoolingAir
Transmission
Gearbox5-speed
Final DriveChain (final drive)
Chassis
Frame TypeArch bar truck
Front SuspensionTelescopic fork
Front Travel110 mm (4.3 inches)
Rear SuspensionTelescopic coil spring oil damped
Rear Travel30 mm (1.2 inches)
Wheelbase1350 mm (53.1 inches)
Ground Clearance185 mm (7.3 inches)
Wheels & Brakes
Front Tyre90/90-17
Rear Tyre120/80-17
Front BrakesSingle disc
Front Brake Ø260 mm (10.2 inches)
Rear BrakesSingle disc
Rear Brake Ø240 mm (9.4 inches)
Dimensions & Weight
Dry Weight136.0 kg (299.8 pounds)
Power/Weight0.0828 HP/kg
Seat Height760 mm (29.9 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.
Suspension
Suspension details can matter for comfort, road feel and long-distance riding.
Transmission
Transmission and final drive affect maintenance, smoothness and everyday usability.
