In the 2020s the whiff of two-stroke exhaust is rare enough to spark memories – if you’re old enough – of a time when 250cc sports bikes were a class of their own, rising above their small capacities and relatively meagre outputs to be the choice of hardcore riders more interested in race bike handling than outright power.
Despite the efforts of the likes of Langen Motorcycles to keep the idea of two-stroke street bikes alive, the chances of strokers making a mainstream return are zero, but there’s a growing revival of small-capacity, screaming sports bikes thanks to burgeoning interest in Asia. We’ve already seen Kawasaki launch the four-cylinder Ninja ZX-25R in Japan and a 400cc ZX-4R is due in 2023 that will reach a wider market, with American sales all but confirmed and the possibility it could be offered over here as well. Elsewhere, Honda’s CBR250RR takes a two-cylinder approach to the same idea while Yamaha’s R3 gives European riders a chance to taste the same sort of small-capacity fun.
Now Aprilia – the firm that was the last man standing when it came to the old generation of 250cc two-strokes, making the Suzuki-powered RS250 until 2004 – appears to be targeting the same market with the development of a new 250cc parallel twin four-stroke engine destined for a future small sports bike.
These pictures come via a design registration for the physical appearance of the new engine, registered by Piaggio’s joint venture with Zongshen in China. We know it’s due to appear in an Aprilia-branded sports bike: currently, Aprilia offers a single-cylinder 250cc version of the RS125 that we get over here in some Asian markets, dubbed GPR250R. The design registration for this new twin-cylinder engine says it is made under the project name ‘GPR250RR’.
As we all know, more Rs means more performance, so the twin-cylinder GPR250RR is sure to be a more exotic machine than the existing, single-cylinder GPR250R.
It’s worth noting that the GPR250R single formed the basis of the track-only Aprilia RS250 SP that was offered in Europe in 2020 as a route into racing for young riders. With only 28hp available, that machine would have limited appeal despite its flyweight 105kg mass, but a twin-cylinder 250 could make substantially more than that. Yamaha’s 321cc R3 is rated at 41.4hp, while Honda’s Japanese CBR250RR hits 40.2hp, and Aprilia’s 250cc twin could achieve similar numbers. It’s not quite the heady 55hp claimed for the old RS250 stroker, but in the right lightweight bike it could still be a recipe for an exciting ride.
The engine is certainly a compact design, clearly showing a DOHC layout and a slightly unusual central drive arrangement for the camshafts, with the cam chain (or perhaps even gears) running between the two cylinders rather than being offset to one side. It’s water-cooled, of course, and not much larger than a 125cc single-cylinder design.
By making the engine and the bikes carrying it in its Chinese factory rather than at Noale, Aprilia will be able to skirt the hefty import duties in that country as well as benefiting from lower production costs. There’s strong demand for small, twin-cylinder sports bikes in China making it a key market for the machine. The question of whether it will also be offered on this side of the world is unanswerable at the moment, and rivals are clearly split in their opinions on the matter – Yamaha sees the R3 as a valuable addition to the European line-up, but Honda and Kawasaki have chosen to leave their 250cc sports models to the Asian markets. But as a European brand, surely Aprilia is more likely than the Japanese firms to bring bikes carrying its name to its home continent.