Before you skip right past all this lovely text and head on down to the comments to tell me about how it isn’t actually 100cc: Yes, that’s completely and totally true.
To start this explainer off on a factual note, while Kawasaki is referring to the bikes currently fitted with its 451cc parallel twin as 500s, they don’t have a full 500 cubic centimeters of displacement.
In fact, there’s an entire 49cc scooter worth of difference between the numbers ‘451’ and ‘500’, according to both my abacus and my calculator.
What we are talking about, however, is Kawasaki’s 451cc “500” and the brand’s 399cc “400.” Get it? No, well that’s why you’re here reading this article. So let’s talk about the differences.
The New Hotness: Kawasaki’s 451cc Parallel Twin Engine
What’s this 451cc parallel twin engine used in? For the 2024 model year, you’ll find it in the Eliminator (or Eliminator 500 in some markets outside the US), the Z500, and the Ninja 500. It’s a four-stroke, double overhead cam, liquid-cooled parallel twin that makes a claimed 51 horsepower at 10,000 rpm and 31.7 pound-feet of torque at 7,500 rpm.
Bore and stroke are 70.0mm by 58.6mm. The compression ratio is 11.3 to one. Physically, Kawasaki says that the new engine maintains the same size as the one found in the previous-gen 400cc parallel twin-equipped models. A small displacement and power jump with the same basic footprint is usually good news in anyone’s book, right?
The Outgoing Classic: Kawasaki’s 399cc Parallel Twin Engine
Both the 2023 Kawasaki Ninja 400 and Z400 make use of Kawasaki’s four-stroke, double overhead cam, liquid-cooled, 399cc parallel twin engine. It makes a claimed 44 horsepower at 10,000 rpm, alongside 28.0 pound-feet of torque at 8,000 rpm.
Bore and stroke are 70.0mm by 51.8mm. The compression ratio is 11.5 to one.
A Manageable Boost
Gallery: 2024 Kawasaki Z500 Engine
On paper, the new engine makes about seven horsepower more than the outgoing engine, as well as very nearly four more pound-feet of torque slightly (very slightly) lower in the rev range.
When you go back in time even further to 2018, you’ll note that the boost is comparable to the approximately 5.9 horsepower boost that the 399cc engine got over the 296cc parallel-twin found in the previous-gen Z300. Incidentally, the Z400/Ninja 400 engine is also where Kawasaki introduced its fancy new combination of downdraft intake and larger airbox, which also carries over to the current-gen 451cc parallel twin that’s hitting the charts in 2024.
TL;DR version: It’s the circle of Kawasaki middleweight parallel twin life, and it moves us all. It’s not going to blow your socks off, but it’s also not meant to do that, either.
Instead, it’s manageable and unintimidating fun, and it’s meant to appeal to riders who are new, returning, and in between—and arguably, those who don’t necessarily feel like they have anything to prove. It’s enough power to get you where you need to go and extricate yourself from sticky situations in traffic, but not so much power it’ll rip your face off.
In other words, it’s probably a pretty good choice for a whole lot of riders.
