Aprilia RS4

Aprilia RS125
2024 Aprilia RS125 GP Replica
ManufacturerAprilia
Also calledAprilia RS125 (2016–present)
Parent companyPiaggio
Productionsince 2011
PredecessorAprilia RS125
ClassSport bike
Engine124.2 cc (8 cu in) Single-Cylinder DOHC four valve four-stroke
Electronic injection
Bore / stroke58.0 by 47.0 millimetres (2.28 in × 1.85 in)
Compression ratio12.5 ± 0.5:1
Transmission6-speed manual, Wet multi-disc cable-actuated clutch, optional Quick Shift (upshifts)
Frame typePerimeter frame, Die-cast Aluminium spars w/ crossed reinforcement ribs
Asymmetric aluminium swingarm
SuspensionFront: Ø40 mm inverted forks
Rear: Progressive monoshock, adjustable preload
BrakesFront: Single Ø300 mm stainless steel disc, radial 4-piston caliper
Rear: Ø218 mm stainless steel disc, single 30 mm piston caliper
ABS: Bosch Dual Channel ABS
TiresFront: 100/80 ZR 17
Rear: 140/70 ZR 17
Wheelbase1353 mm
DimensionsL: 1968 mm
W: 760 mm [w/ mirrors]
H: 1135 mm
Seat height820 mm (32 in)
Weight129 kg (dry)
144 kg (wet)
Fuel capacity14.5 L (3.2 imp gal; 3.8 US gal)
Reserve: 3.5 L (0.77 imp gal; 0.92 US gal)
Fuel consumption2.71 L/100km
RelatedAprilia RS4 50
Aprilia Tuono 125
Derbi GPR125

The Aprilia RS4 125 (sold as the RS125 since 2016) is a 125 cc class sportbike manufactured by Italian motorcycle firm Aprilia. The four-stroke RS4 125 replaces the extremely popular RS125 two-stroke race replica in Aprilia's lineup. The bike is based on the four-stroke version of the Derbi GPR125.