At the heart of the 2011 Aprilia RS4 50 sport motorcycle, Aprilia utilizes a 49.9 cc (3 cu in) liquid-cooled single cylinder, two-stroke layout. Internal engine geometry specifies a bore and stroke of 39.9 x 40.0 mm (1.6 x 1.6 inches) with a 11.5:1 compression ratio.
Rider ergonomics and chassis geometry center around a 820 mm (32.3 in) seat height — resulting in a taller command-style riding posture suited to medium-to-tall inseams, combined with a 1,350 mm (53.1 in) wheelbase engineered for quick, flickable steering geometry. The 14.5-liter (3.8 US gal) fuel tank supports practical everyday commuting and weekend road stints.
Within MotoLibrary's Aprilia archive, this model family spans 7 indexed model years from 2011 to 2018, allowing buyers to track year-over-year changes in emissions tuning, weight and equipment.
Standover Height
820 mm (32.3 in)
Engine
Displacement49.9 ccm (3.04 cubic inches)
Engine TypeSingle cylinder, two-stroke
Engine DetailsSingle cylinder, two-stroke
Compression11.5:1
Bore x Stroke39.9 x 40.0 mm (1.6 x 1.6 inches)
Fuel SystemCarburettor. Dell’Orto PHVA – 17.5
IgnitionElettronica C.D.I.
LubricationAutomatic mixer
CoolingLiquid
Transmission
Gearbox6-speed
Final DriveChain (final drive)
ClutchMulti-plate
DrivelinePrimary drive: Gears. Ratio: 21/78. Final drive: Chain. Ratio: 14/53
Performance
Emission DetailsEuro 2
Chassis
Frame TypeTwin spar aluminium frame
Front Suspension40 mm upside down fork
Front Travel110 mm (4.3 inches)
Rear SuspensionAsymmetric swingarm with monoshock
Rear Travel130 mm (5.1 inches)
Wheelbase1350 mm (53.1 inches)
Wheels & Brakes
Front Tyre110/80-17
Rear Tyre130/70-17
Front BrakesSingle disc
Front Brake Ø300 mm (11.8 inches)
Rear BrakesSingle disc
Rear Brake Ø180 mm (7.1 inches)
Wheelslight alloy with 6 split spokes, with sealing profile for tubeless tyres
Dimensions & Weight
Seat Height820 mm (32.3 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.
Seat Height
Check the seat height against your inseam and riding posture before choosing a motorcycle.
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.
