Kawasaki of Indonesia recently published a video featuring the instrument panel of the upcoming ZX-25R looks like. At first glance, there might not be anything special about it until you see red numbers that start at 17 and go all the way to 20.
So what does that mean? Tachometers indicate the revolutions per minute of an engine's crankshaft, multiplied by 1,000. That being said, seeing a “20” on the tachometer translates to a whopping 20,000 RPM. The white digits are figures that an engine will easily rev to, while the red digits comprise the redline: the maximum revolutions an engine can perform for brief periods.
To put it in perspective, a typical sportbike, say a BMW S 1000 RR with a 1000cc inline-4, has a redline of 14,200 RPM, while a Formula One car has a 1.6-liter V6 that can redline at 18,000 but sometimes goes beyond 19,000 RPM. The fact that the 250cc inline-4 of Kawasaki can rev even higher than a large BMW inline-4 is rather impressive.
What's the big deal?
High redlines are nothing new to motorcycles. Old two-stroke engines boasted of famously-high (for the time) redlines, hitting 16-17,000, earning them the name, screamers. Perhaps the golden age for these bikes was in the late 80s and early 90s, with bikes like Honda's NSRs, Suzuki's GSX-Rs, Kawasaki's ZX-Rs, and Yamaha's TZR models.
At the time, with little to no emissions restrictions, two-stroke engines were preferred for motorcycles because they were lighweight and compact engines. They produced lots of emissions, very little horsepower and torque at low revs, consumed a lot of fuel, and weren't as reliable. Nonetheless, these weren't big concerns at the time. Many motorcycle manufacturers compensated for their downsides with higher redlines to produce more power, resulting in the screaming sound. These allowed even small motorcycles with 250cc engines to reach speeds close to or beyond 200 km/h. Best of all, they were very affordable.
Their tuning also produced a very narrow and peaky powerband, making them somewhat difficult to master and prone to wheelspins and losing traction. They were called "widowmakers" because they so frequently made the wives of their owners widows if there was an accident.
What happened to them?
With tightening emissions restrictions around the world, many motorcycle brands shifted to four-stroke engines because they could more easily meet these requirements. With more power and torque coming in lower in the rev range, there was little need to make these engines rev high. Since then, engine redlines have gone down from the astronomically high 17,000 RPM to an average of 11-12,000 RPM.
What can we expect?
Kawasaki's upcoming ZX-25R, in a way, is a modern-day remake of these kinds of motorcycles, combining the high-revving scream and high horsepower relative to its size of an old two-stroke, with the low emissions, fuel-efficiency, and reliability of a four-stroke.
As of this writing, Kawasaki has not released the exact power figures of the ZX-25R, but some experts speculate it can produce as much as 61 Ps. it may not sound like much, but keep in mind that the current Ninja 400, powered by a parallel twin, only produces 49 Ps. Most 400cc motorcycles typically reach a top speed of 160-180 km/h. The ZX-25R may be easily able to hit 200 - 225 km/h with its very high-revving engine. Finally, because it's a four-cylinder it will definitely consume more fuel. A typical 250cc single-clyinder or parallel twin returns 30-40 km/L. This ZX-25R may only be able to return 25-30 km/L at best.
Kawasaki Motors Philippines Corp. has yet to confirm if the ZX-25R will be sold here next year, alongside the new Z H2, but let's keep our fingers crossed. If it does, things could get very intereting on the streets.