Positioned in Derbi's scooter motorcycle lineup, the 2011 Derbi Sonar 125 4T relies on a 124 cc (7.6 cu in) air-cooled single cylinder, four-stroke powerplant. In factory specification, peak output is rated at 10.6 HP (7.7 kW) at 8,000 rpm while maximum torque reaches 9.6 Nm (7.1 lb-ft) at 7,250 rpm, transferring power to the rear wheel through a automatic gearbox and belt final drive. With a specific output of 85.5 HP per liter and a 750 rpm working window between peak torque (7,250 rpm) and peak power (8,000 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 Sonar 125 4T measures 99 kg (218 lbs) dry, translating to a power-to-weight ratio of 0.11 HP/kg (9.34 kg per horsepower). Rider ergonomics and chassis geometry center around a 805 mm (31.7 in) seat height — offering a neutral standover height that accommodates most average-inseam riders without sacrificing cornering clearance, combined with a 1,325 mm (52.2 in) wheelbase engineered for quick, flickable steering geometry. The 6-liter (1.6 US gal) fuel tank supports practical everyday commuting and weekend road stints.
Within MotoLibrary's Derbi archive, this model family spans 3 indexed model years from 2010 to 2012, allowing buyers to track year-over-year changes in emissions tuning, weight and equipment.
Specific Output
85.5 HP/L
Power-to-Weight
0.11 HP/kg (9.34 kg/HP)
Power Band Window
7,250–8,000 rpm
Standover Height
805 mm (31.7 in)
Engine
Displacement124.0 ccm (7.57 cubic inches)
Engine TypeSingle cylinder, four-stroke
Engine DetailsSingle cylinder, four-stroke
Power10.6 HP (7.7 kW)) @ 8000 RPM
Torque9.6 Nm (1.0 kgf-m or 7.1 ft.lbs) @ 7250 RPM
Compression10.6:1
Bore x Stroke57.0 x 48.6 mm (2.2 x 1.9 inches)
Fuel SystemCarburettor
LubricationMechanical oil pump
CoolingAir
Transmission
GearboxAutomatic
Final DriveBelt (final drive)
ClutchAutomatic centrifugal
Performance
Emission DetailsCompartment underthe seat to hold a jet helmet.
Chassis
Front Suspension32 mm fork.
Front Travel76 mm (3.0 inches)
Rear SuspensionMonoshock
Rear Travel64 mm (2.5 inches)
Wheelbase1325 mm (52.2 inches)
Wheels & Brakes
Front Tyre90/80-16
Rear Tyre110/80-14
Front BrakesSingle disc
Front Brake Ø220 mm (8.7 inches)
Rear BrakesExpanding brake (drum brake)
Rear Brake Ø140 mm (5.5 inches)
Dimensions & Weight
Dry Weight99.0 kg (218.3 pounds)
Power/Weight0.1071 HP/kg
Seat Height805 mm (31.7 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.
