Aprilia introduced the RS125 in 1992 as a road-legal homage to its Grand Prix racing machinery, drawing directly on the company's deep involvement in the 125 cc World Championship. The engine was supplied by the Austrian firm Rotax — the same manufacturer that powered Aprilia's factory racers — and featured a Nikasil-coated aluminium cylinder block with liquid cooling. The original model was sold in red and black livery and carried the RS 125 R designation on the tank, with buyers choosing between electric or kick-start variants.
The first generation RS125 featured angular bodywork, a square-cut headlight, three-spoke rims, and analogue gauges. Air scoops positioned on the upper front fairing were a distinctive styling element. The Extrema designation identified this founding variant, and production reached its peak in 1994.
A revised second generation dropped the Extrema name while retaining the core silhouette. Styling changes included a rounded headlight unit with a pronounced upper lip, integrated front air intakes within the upper fairing section, and a digital gauge replacing the temperature gauge. The most significant mechanical update for the Italian domestic market was the introduction of the Rotax 122 engine, an improved successor to the outgoing Rotax 123. Most European markets continued using the Rotax 123 through 1997 and in some cases into 1998.
A third restyling in 1999 gave the RS125 more rounded and bulbous fairings, five-spoke rims, and a single air duct positioned on the rider's right-hand side. The headlight lip was enlarged further. This generation broadened the bike's appeal to a younger rider demographic looking for an accessible performance motorcycle with genuine racing lineage.
The most comprehensive redesign of the two-stroke era arrived in 2006, with angular new bodywork modelled closely on the RSV 1000R superbike. Twin headlight bulbs, a digital instrument cluster, and multi-spoke Marchesini-styled rims modernised the appearance. Radial four-piston brake calipers and braided brake lines improved stopping performance. In 2008 the electronics package was updated from Nippon-Denso components to an EFI Technology ECU, and a new Dell'Orto 28 mm VHST CD carburettor was fitted to meet tightening Euro 3 emissions requirements. The two-stroke RS125 line ended in 2012 when Aprilia replaced it with the RS4 125, a bike using a single-cylinder four-stroke fuel-injected engine — marking the end of an era for two-stroke road machinery in mainstream European markets.
For 2019, with the shift to Euro 4 emissions standards, Aprilia renamed the RS4 125 back to RS 125. The four-stroke single-cylinder engine carried over from its predecessor, but the new emissions tune brought reduced power and torque compared to the old two-stroke. Subsequent updates arrived in 2021 and 2025, targeting Euro 5 and Euro 5+ compliance respectively, along with design revisions, electronics improvements, and a wider rear tyre.
Aprilia briefly offered a semi-naked derivative called the RS125 Tuono from 2003 to 2004. The Tuono removed the lower and middle fairing sections and fitted conventional handlebars to the top yoke in place of clip-ons, creating a more upright riding position. It was discontinued after two production years.
The RS125 occupies a significant place in European motorcycling culture as one of the definitive learner-legal performance bikes of the 1990s and 2000s. Its direct mechanical kinship with Aprilia's championship-winning Grand Prix machinery gave it credibility that few rivals could match, and it introduced generations of young riders to the performance potential of small-displacement two-stroke engines. The model's name survived the transition to four-stroke power, testament to the strength of the RS125 brand identity.
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