2011 Aprilia RS4 125

tested the RS4 125 in a learner-legal version that generates 15 horsepower at 10,500 rpm. Peak torque of 8.1 ft-lb occurs at 8500 rpm. Its 75-mph top speed enables safe riding on motorways, and the engine isn’t going to blow up after long runs on the highway. The four-stroke torque curve enables cruising from 8,500 rpm and a very decent fuel range.

2011 Aprilia RS4 125

The 300mm disc up front offers sharp response.

I, however, tested on a race track, so I spent pretty much all the time testing in the range between 10,000 and 11,000 rpm 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 losing revs must be avoided at all cost. Compared to a 2-stroke, though, there’s plenty of midrange. I had lots of fun slipstreaming the other journalists on the circuit just like they do in the 125 GP championship, but it got slightly boring as soon as I found myself without anybody to chase down.


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 off was never great.