2011 Aprilia RS4 125 | Review

Aprilia 125cc

I remember watching Mick Doohan winning 500GP races whilst Valentino Rossi, Max Biaggi and Loris Capirossi battled it out on the Aprilia RS 125s and 250s in the late nineties. This was the heyday for the 2-strokes.

In 2011 you can still buy the legendary RS 125 but the future is the RS4 125 that I’ve tested at the ASC Vairano circuit in the North of Italy…

Everybody knows that the 125cc 2-strokes are faster more efficient engines. The RS 125 can be tuned to around 33 horsepower whilst the RS4 125 can be tuned to around 25 horsepower as an 180cc bike.

Nobody at Aprilia is saying that the RS4 125 can replace the RS 125 performance wise because it can’t. The RS4 125 benefits from a reliable 125cc four stroke engine that doesn’t need a rebuild every 10,000 miles. The RS4 125 is also more environmentally friendly using less fuel and oil compared to the 2-strokes. All in all the RS4 125 is a much cheaper bike taking all considerations including running cost.

I tested the RS4 125 in learner legal version where 15 horsepower is available at 10,500rpm and 11Nm of torque at 8,500rpm. The 120km/h top speed enables safe riding on motorways and the engine isn’t going to blow up after long runs at top speed.

The four-stroke torque curve enables cruising from 8,500 rpm and a very decent fuel range. I however tested on a race track so I spent pretty much all the time testing in the range between 10,500rpm and 11,000rpm where the engine pulls much better than anywhere else in the power range.

It’s a narrow range for riding fast and I quickly found out that loosing revs must be avoided at all cost. Compared to a 2-stroke there’s plenty of midrange though. I must admit that I had lots of fun racing the other journalists on the circuit and it got slightly boring as soon as I found myself without anybody to chase down. Just like they do in the 125 GP championship we slipstreamed each other to enable overtaking on the brakes.

And the brakes on the RS4 125 are very sharp consisting of a 300mm disc and a 4-pot radial calliper. I hardly used the 200mm rear brake at all as let’s face it, the speed needed to be brushed of was never great and from top speed only 30-40 odd kilometres as I always needed momentum for as high a corner speed as possible.

The dry weight is a claimed 134kg (RS 125 approx 121kg) which is lightweight for a four stroke. Admittedly I’m quite large for the RS4 125 but on the pictures you could briefly think that I’m on the RSV4 rather than the RS4. The suspension is not adjustable and to my surprise Aprilia has found a good standard set-up as I had nothing to complain about chassis wise. I presume the small motorcycle handles even better with a lighter rider which I again presume most 16-year olds are. The tires are of sizes 100/80-17 front and a 130/70-17 rear.

The amount of ground clearance is great and there’s a very noticeable loss of revs as soon as I went from full lean to upright position as you’ve only got a 500rpm window of max power before loosing power. It’s obvious from my onboard video that I wasn’t fully aware of just how much loss of revs as I sometimes shifted up at full lean which is natural on a larger capacity bike but on the 125 it’s best to just use over revs as it’s still not enough power to upset the rear tire and nothing to gain until max power has been reached whilst having the bike stood up.

Aprilia offer a quick shifter as an accessory and trying this on the circuit there’s no doubt this is of great benefit to the small 125 as acceleration suffer on the version without Quick shifter due to loss of revs.

The RS4 125 is pretty much a premium 125 in the first place but with the quick shifter it’s like a superbike for the youngsters. The pricing in the UK is not that stiff compared to the competition which mainly are the Honda CBR 125R (£3,270 OTR) and Yamaha YZF R125 (£4,249 +reg+tax).

The Aprilia RS4 125 RRP is £3,999 OTR + £99 for the quick shifter. All the 125cc supersport replicas are relatively expensive and my guess is that those 16 and 17 year olds that can afford one can thank their parents for the privilege. When I was 13-14 years old I did a paper round after school and made about £100 every fortnight. You have to want one badly from an early age to save up for more than two years without any financial assistance.

I only tested the RS4 125 on the circuit but it’s evident that the small 125 will work as a very good road bike as well. No expensive 2-stroke oil, just fuel and very little of it. The fairing is nearly identical to the big RSV4 superbike and two large headlights make sure this 125 looks like any other motorcycle in a cars rear view mirror. The exhaust is a stylish hidden low by the fairing affair and it sounds a bit more grown up than a 2-stroke.

The seat is sporty and comfort levels are the same as on any sportbike and this goes for the ergonomics in general. The rear seat cowling can be replaced by a pillion seat and underneath there’s room for a few bits and bobs. The mirrors are wide and give good view of traffic coming from behind.


All in all the Aprilia RS4 125 is a proper dreambike for youngsters but it’s also got some benefits for those a bit older without a full motorcycle license. It looks like a fully grown sportbike and has enough top speed to follow motorway traffic even in restricted form. Scooters are a good means of transport but the RS4 125 are for those that really want to ride in the same way as you do on a large capacity motorcycle. With the added benefit of the quick shifter all you do is push the starter button, engage first gear and then just full throttle whilst shifting up. Remember to use the clutch when downshifting though…

2011 Aprilia RS4 125 Positives:

  • Big bike looks and Aprilia style and heritage
  • Great brakes
  • A learner motorcycle where you really do learn the ABC of motorcycling
  • Much greater second hand value than the 2-stroke RS 125

2011 Aprilia RS4 125 Negatives:

  • Slightly stiff pricing but this goes for all the R replicas in this segment


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