Same RS badge, very different eras
Set a 1998 Aprilia RS 250 beside today's RS 660 and the badge is one of the first things you notice. Both are fully faired road-going Aprilias with a sporting purpose. Both make a strong case for looking beyond engine capacity when discussing what a sports motorcycle is built to do.
But the more interesting comparison is what changed between them.
The RS 250 belongs to an era when a 250 cc two-stroke twin could sit at the sharp end of the road-sport conversation. The RS 660 approaches that territory with a 659 cc four-stroke parallel twin, a substantial electronic control package and a chassis designed around modern road use as well as sporting performance. They represent very different answers to the question of how Aprilia should make a relatively compact, fully faired performance motorcycle.
The years matter. The historic reference here is the European road RS 250 in Aprilia's Model 1998 specification, not an earlier machine or a Grand Prix racer. The modern reference is the current standard UK/EU RS 660, not the Factory version, a restricted machine or a track conversion.
There is also a distinction worth making before the specifications begin: sharing the RS name does not establish that the RS 660 directly replaced the RS 250. This is a comparison of two road-sport eras, not a claim that Aprilia built one as the designated successor to the other.
The 1998 RS 250: a road two-stroke from another period
By 1998 the RS 250 was already an established part of Aprilia's road range, having arrived in the mid-1990s. Its engine was a liquid-cooled, 249.25 cc, 90-degree two-stroke V-twin. It was closely related to the Suzuki RGV250 road engine, with Aprilia's own development and installation choices around the package. It was not an Aprilia Grand Prix 250 engine placed inside a road motorcycle.
That distinction does not diminish the RS 250. The road bike's appeal came from bringing a compact two-stroke engine together with an aluminium twin-beam chassis, serious suspension, powerful disc brakes and a committed sports riding position. The bodywork carried a clear racing association, but the machines racing in the 250 cc Grands Prix were separate motorcycles.
The official 1998 handbook describes a motorcycle with a six-speed gearbox, a 19.5-litre fuel tank and an 810 mm seat. It records 167 kg ready for starting. That last phrase is important: it is the handbook's own measurement description, not an invitation to compare the number directly with a modern EU wet-mass figure.
There was electronic control in the RS 250's engine systems, and the period instrumentation was not simply a collection of mechanical dials. But the rider did not have the modern package of lean-angle-sensitive traction control, selectable riding modes, cornering ABS and cruise control that now forms part of the RS 660's standard equipment.
Even in its own decade, the RS 250's specification could vary by market and production phase. A 1998 reference should not borrow an earlier power claim, a race-only specification or a magazine's measured rear-wheel output and present it as one universal official figure. For this comparison, the engine type and design are more useful than forcing a disputed peak-power number into the story.
The current RS 660: a different modern sports-bike proposition
Aprilia's current standard RS 660 changes almost every part of that mechanical equation. It uses a liquid-cooled, four-stroke parallel twin of 659 cc with ride-by-wire throttle control. Aprilia gives the present standard motorcycle 105 hp at 10,400 rpm and 70 Nm at 8,400 rpm.
These figures belong to the updated standard road machine. They should not be confused with the earlier 100 hp phase, the 35 kW restricted motorcycle or the distinct RS 660 Factory equipment package.
Its aluminium twin-spar frame makes the two machines interesting to compare. Aprilia did not abandon aluminium chassis construction, but the modern motorcycle uses a very different engine and packaging arrangement. The present RS 660 has a Kayaba 41 mm upside-down fork, a Kayaba rear monoshock and twin 320 mm front discs with Brembo radial callipers. Those are actual standard-bike specifications, rather than equipment borrowed from the Factory model.
The details around the rider also show how much the brief has expanded. There is a five-inch TFT display, modern lighting, ride-by-wire throttle, cruise control and electronic aids that interact with the motorcycle's six-axis inertial platform. Aprilia's 2025 update introduced fresh aerodynamic winglets, revised instrumentation and launch control alongside the power increase.
None of this makes the RS 660 a touring bike, or an uncomplicated beginner's machine. It remains a sporting road motorcycle. What changes is the number of jobs its systems are designed to manage: engine response, traction, braking, wheelie control and the rider's ability to choose different settings for different conditions.
The current technical sheet lists an 820 mm seat, a 15-litre tank and 183 kg wet, measured under the stated EU basis with standard equipment, fluids and at least 90 per cent of usable fuel. Those figures are useful for understanding the current model on its own terms; they are not a clean weight ranking against the 1998 RS 250.
Two-stroke V-twin versus four-stroke parallel twin
The most fundamental difference is not the extra 409.75 cc. It is the way the engines work.
The RS 250's two-stroke twin completes its working cycle in one revolution of the crankshaft. Its exhaust-port control, separate lubrication and intake arrangement are part of a design that asks for a different approach to combustion and power delivery from a modern four-stroke. The 1998 handbook's technical section records the two-cylinder, 90-degree configuration, liquid cooling and automatic variable oil-mixing system.
The RS 660's four-stroke twin completes its working cycle across two crankshaft revolutions, with cam-operated valves and a modern electronic management system. It delivers its quoted output through an engine with much more capacity and a different architecture; calling it a larger RS 250 engine would miss the point entirely.
Capacity itself can be misleading across those two technologies. A two-stroke 250 and a four-stroke 659 are not the same sort of engine scaled to different sizes. Comparing them simply as 250 against 660 would say remarkably little about the motorcycles' actual character or design requirements.
The Suzuki connection on the older road bike is equally easy to misread. Aprilia adapted an RGV-derived production engine for the RS 250. Its racing image came from the bodywork, the company's competition identity and the kind of compact high-performance motorcycle the market understood at the time. That is not the same as using the engine from an Aprilia factory Grand Prix machine.
The modern RS 660 is built around an entirely separate engine concept. The RS 660's four-stroke twin is not a development of the RS 250's production two-stroke V-twin.
Chassis, brakes and suspension across the gap
It would be too neat to describe the older motorcycle as technically simple and the newer one as sophisticated. The RS 250 had serious chassis engineering for its day. Aprilia's 1998 workshop literature treats the aluminium frame, suspension and brakes as developed road-sport hardware, with model-year changes that deserve their own reference treatment.
The RS 660 carries that emphasis on a capable sporting chassis, but does it with different dimensions, wheel and suspension specifications, and a completely different engine installation. Its standard 41 mm Kayaba front fork offers rebound and preload adjustment; the rear Kayaba unit also has adjustability. The front brake system uses twin 320 mm discs and radial Brembo callipers. The current technical sheet gives the precise specification; the older RS 250 should not be reduced to a generic 'small-bike' chassis by comparison.
The greater change is the integration of all the systems around that hardware. Suspension and brakes were critical on the RS 250, but their operation was not overseen by the kind of inertial, electronically assisted rider-control platform available on the RS 660.
Even the apparently straightforward size and mass comparison has limits. The 1998 RS 250 handbook reports 167 kg ready for starting; the modern RS 660's 183 kg is defined under a specific wet-mass regulation. Without a common measurement basis, subtracting the numbers to claim an exact advantage would be false precision.
The same applies to a power-to-weight ranking. One side does not have a clean, configuration-matched official road-power figure in the accepted 1998 evidence, and the mass bases differ. The two motorcycles can be compared meaningfully without inventing an exact ratio.
From period electronics to APRC
The difference between these machines becomes particularly clear at the handlebars.
A 1998 RS 250 rider managed the engine with a conventional cable throttle, a clutch lever, the gearbox and the controls of a high-performance road two-stroke. The engine included electronically managed functions, and the motorcycle's instruments supplied useful information, so describing it as having 'no electronics' would be misleading.
But today's RS 660 adds systems that actively respond to what the motorcycle is doing. Its standard APRC package works with a six-axis inertial platform and includes traction and wheelie control, engine-map and engine-brake management, cornering ABS and five riding modes. Aprilia Quick Shift, cruise control and launch control are also part of the current standard specification.
These are not just features to list on a brochure. They change what the rider can ask the motorcycle to manage. The RS 250's controls put a greater share of throttle, clutch, braking and traction judgement directly in the rider's hands. The RS 660 still demands judgement, but offers electronic systems that can intervene or adjust behaviour within their designed limits.
There is no need to call one approach purer. They belong to different engineering and regulatory periods, with different expectations of a road-registered sports motorcycle.
What regulation changed — and what it does not prove
The regulatory contrast is real. The 1998 RS 250 documentation distinguishes versions and includes instructions relevant to catalytic silencers. The current RS 660 belongs to the Euro 5+ era, with a manufacturer technical sheet specifying a current four-stroke road configuration.
That is a very different environment for making and selling a fully faired sports motorcycle. Exhaust emissions, noise requirements, type approval and customer expectations all shape modern road-bike development. It is reasonable to discuss those changes together; it is not reasonable to declare, without a documented causal chain, that one specific emissions rule killed the RS 250 and directly created the RS 660.
Nor does the RS 250's GP-inspired appearance make its road engine a Grand Prix engine. Racing imagery and engineering identity are different things. Aprilia's original road motorcycle and its Grand Prix race bikes should be discussed with their own equipment and histories intact.
The RS 660 illustrates the modern design response: a road-legal four-stroke twin, electronically managed controls, current emissions compliance and performance-oriented chassis hardware in one standard production motorcycle. It tells us plenty about today's expectations without requiring a fabricated replacement story.
Is the RS 660 really the RS 250's successor?
Not on the evidence of a shared name alone.
The RS 250 was a mid-1990s two-stroke road sports motorcycle, with this article anchored to its 1998 European form. The RS 660 is a current four-stroke middleweight with a substantially larger engine and a different performance and rider-aid brief. Aprilia has used RS branding across different motorcycles and periods, but that does not automatically create a direct model-to-model succession.
It is more accurate to treat them as two points in Aprilia's road-sport history. They show how the manufacturer has worked with different engine technologies, customer expectations and regulatory contexts under a broadly sporting name.
That distinction is more useful than saying the RS 660 is an RS 250 'reborn'. Such a label would suggest a product-development relationship that the technical details alone cannot demonstrate.
What this comparison tells us
The RS 250 and RS 660 show two different ways to make a compelling road-registered sports motorcycle.
In the 1998 RS 250, the centre of the package was a small-capacity two-stroke V-twin combined with aluminium-framed sporting hardware. Engine behaviour, rider input and period chassis design were defining parts of the experience the motorcycle was built to offer. Its race association was visible, but its road engine and road specification had their own identity.
The standard RS 660 offers a different balance. Its 659 cc four-stroke twin, current-generation electronics, adjustable Kayaba suspension and Brembo brakes form a coherent modern road-sport proposition. Aprilia has not simply increased capacity and added a display. The systems available to the rider, the engine's working cycle and the regulatory assumptions behind the motorcycle have all changed.
You do not need a winner, or a claim of direct descent, to see the connection. These are two eras of Aprilia using a compact, fully faired sporting motorcycle to answer the expectations of its time.
The RS badge is the invitation to compare them. The engineering explains why they are different.
Read next on Superbike Vault
For exact historical specifications, version boundaries and the remaining figure qualifications, explore the Aprilia RS 250 Model page. The Aprilia RS 660 Model page holds the current standard road specification and separates it from Factory and restricted configurations.
The Aprilia Brand page gives broader manufacturer context. For a different thread of Aprilia engineering history, Aprilia RSV Mille to RSV4 follows the marque's big-bore superbike development, not the RS 250-to-RS 660 comparison here.
