Aprilia RS 125

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Make Model	Aprilia RS 125 R
Year	2008
Engine	Single cylinder, two stroke, reed valves induction
Capacity	124.8 cc / 7.5 cu in
Bore x Stroke	54 x 54.5mm
Compression Ratio	12.5:1
Cooling System	Liquid cooled
Lubrication	Separate mixing, volumetric pump
Induction	Dell'Orto PHBH 28 carburetor
Ignition	CDI electronic ignition
Starting	Electric
Alternator	12V, 180W
Max Power	21 kW / 28 hp  @ 10500 rpm
Max Torque	19 Nm / 1.9 kgf-m / 14.1 lb-ft @ 9000 rpm
Clutch	Wet, multi-disc
Transmission	6 Speed
Final Drive	Chain
Gear Ratios	1st 10:30 / 2nd 14:29 / 3rd 17:27 / 4th 19:25 / 5th 21:24 / 6th 22:23
Primary Drive	63:19
Final Drive	17:40
Frame	Cast aluminium, reinforced box section, sloping twin-spar frame
Front Suspension	Upside-down forks, Ø 40mm
Front Wheel Travel	120 mm / 4.7 in
Rear Suspension	Monoshock, cast aluminium box section swingarm with asymmetric members
Rear Wheel Travel	Single Ø 320 mm floating discs, 4 piston radial caliper
Front Brakes	120 mm / 4.7 in
Rear Brakes	Single Ø 220 mm disc, 2 piston caliper
Wheels	Aluminium alloy
Front Rim	3.00 x 17
Rear Rim	4.00 x 17
Front Tyre	110/70-17
Rear Tyre	150/60-17
Dimensions	Length: 1955 mm / 77.0 in Width: 720 mm / 28.3 in Height: 1100 mm / 43.3 in
Wheelbase	1345 mm / 53.0 in
Seat Height	805 mm / 31.7 in
Dry Weight	115 kg / 254 lbs
Wet Weight	142 kg / 313 lbs
Fuel Capacity	14 L / 3.7 US gal
Top Speed	155 km/h / 96 mph
Review	Motorcycle USA

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Review

Year after year, we squint at the computer screen just to get a glimpse of some of the ultra-cool euro spec-only motorcycles seen at international bike shows the like Cologne and Milan. We slowly digest the words searching for that precious phrase: 'coming to the US.’ A few choice words after are then blurted out as we discover that yet again a cool new bike is being withheld from us.

But for 2009, it seems we’ve finally gotten our wish as one such bike is coming to America for the first time ever. And you can have one—just as long as you don’t plan on riding it on the street. That’s right, despite its road-going good looks, complete with a headlight and taillight, this bike is strictly for closed-course only thanks to EPA emission standards. Meet the 2009 Aprilia RS125.

 Whether moving or at a standstill, the RS125 is a sharp-looking motorcycle and despite its petite size by no means is it a playbike. Everything from its glossy, sponsor emblazed bodywork to the race-replica magnesium painted triple clamp, polished frame and swingarm, multi-spoke wheels, and gold brakes look they’re straight off an Aprilia GP racer. Powering this pint-sized replica racer is a liquid-cooled, 125cc 2-stroke manufactured by renowned Austrian engine builder, Rotax. Engine fueling is achieved via a 28mm Dell’Orto carburetor and a reed valve intake, while a sleek left-hand exhaust does away with spent fuel.

The engine is wedged inside a rigid GP-inspired slim twin-spar polished aluminum frame and is suspended via a 40mm inverted fork and a hydraulic rear shock. Up front, braking duties are handled by a single 320mm disc with a radial-mount, four-piston caliper, while a single 220mm, twin-piston caliper extends on the back of the polished and curvaceous swingarm.

With a claimed dry weight of just 280 pounds, there’s no question that the RS125 is a small bike. However, to our surprise, hopping aboard it isn’t as cramped as we anticipated and is nowhere near as tight as a full-on 125 GP racer. The handlebars include standard road-going fare such as turn signals, headlight switch and horn. Instrumentation consists of a swept analog tachometer that also houses a digital display providing speed, trip information and coolant temperature.

Firing the engine is as easy as pushing down on the handlebar mounted choke lever and thumbing the starter button. There’s no need to mix any special fuel concoction as the engine is oil-injected, so gas and oil are topped off separately. The engine comes alive quickly and greets its rider with the pungent aroma of burnt oil and gas. Once warmed up, it idles evenly around 1000 revs.

Launching from a stop requires some clutch finesse as the little one dinger doesn’t have anywhere near the amount of torque as a 4-stroke engine. As you accelerate the Single seems to gain momentum in protest. But as the rpms progressively increase, the engine begins to spool up quicker. That glorious 2-stroke “braappp” matches engine speed and as soon as the crankshaft spins to that magic 10,000 rpm, the engine springs to life and finally rewards its riders with some decent acceleration. Remember to shift though, because if you keep the throttle pinned for just a few seconds longer, the fun is over just as quick as it started.

Out on Willows Springs International Raceway’s 1.8-mile Streets of Willow course, the six-speed transmission does an admirable job of keeping the little engine zinging for most of the track, although the final drive gearing is defiantly on the tall side considering the engines modest power output. Going up both the front straightaway into Turn 1 or onto the back straightaway, you’ll defiantly be wishing for more juice. Everywhere else you’ll be giggling inside your helmet, for what the RS lacks in the power department, it makes up for in handling.

Changing directions requires almost no muscle movement and is as simple as looking ahead at where you want to go. In fact, the little RS turns-in so sharply, that it takes a few laps for your brain to acclimate to just how immediate this replica-racer responds. Pretty soon, you’ll find yourself tackling every aspect of a corner—from entry to exit— faster than you probably ever have.

Ground Clearance is plentiful as the racetrack-inspired rearsets are high and even with the OE Dunlop street rubber, the little RS is capable of obtaining some astonishing levels of lean. Body position is far more essential as compared to a big 4-stroker and fortunately there is enough room within the cockpit for even a tall rider to maneuver their weight where it needs to be. And when you put it all together through fast sweepers like the Streets 20-degree bowl turn, you’ll be going fast enough to feel the laws of gravity making it a sensory experience like nothing most have ever felt aboard any motorcycle, myself included.

Near maximum lean, the machines rigid frame, swingarm and soft suspension make for an interesting ride. Paired together with its modest power output, quick handling, and absurd levels of lean, you won’t find yourself using the front brakes much, which in effect makes it so the bike’s fork never needs to use all of its travel.

Suspension adjustability is limited to only rear spring preload adjustment; nonetheless, given its small size and the fact that it’s so light; you won’t miss the lack of adjustment. For the rare time you might need to slow down, the brakes are more than capable of stopping the bike in a hurry.

Within our market, where 4-strokes rule, the eighth-liter RS is a refreshing alternative despite its less than everyday practicality. While the $5499 RS125 certainly isn’t for everybody, pound for pound, it’s a blast to ride on the track. Not only is it fun and responsive, it’s a motorcycle that just begs to be ridden on the pipe and at maximum lean. And when you ride it just right, it rewards the rider with a Zen-like experience that has to be experienced to truly be understood.