The Cheapest Inline-Four Motorcycle In 2025

With most big motorcycle manufacturers pivoting away from small-displacement inline-4 engines, it came as a pretty big surprise when Kawasaki launched this sports bike. It was a fairly big gamble at the time, but so far the reception of the model has been unequivocally positive. That is primarily because this serves as something of a throwback motorcycle.

Even though it is “new” and isn’t trying to lure buyers in with retro appeal, it is a bike that really is all about its engine. An engine, or at least an engine configuration that rose to prominence back in the late 80s and early 90s, long before noise and emissions restrictions were a thing. It certainly sticks out in a market segment currently dominated by parallel-twins – and some singles – as an alternative option that cuts against the grain in more ways than one.

Trick Star Kawasaki Ninja ZX-4R

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The Cheapest Inline-4 Motorcycle In 2025: Kawasaki Ninja ZX-4R

MSRP: $8,999

Kawasaki Ninja ZX-4R

One interesting fact is that it isn’t the smallest inline-4 currently in production. That honor currently belongs to the bike that inspired this model: the ZX-25R. Kawasaki saw a small gap in the sports bike market and decided to develop a new small-bore inline-4, mostly for sub-300cc racing. The reception was so good throughout Asia that the brand took it a step further and developed one of the most exotic little bikes for the global market in the form of the ZX-4R.

We say exotic because while this is the cheapest inline-4, it is by no stretch of the imagination “cheap.” As it stands, it is very much an island, stuck between the entry-level sports bikes like the KTM RC 390 and modern supersports like the Honda CBR650R. With it being so very different, it is pretty hard to say exactly what this little bike is actually for. It certainly isn’t beginner-friendly. Kawasaki already has that end of the market taken care of with the Ninja 500 anyway. Plus, it isn’t quite up to the same standard as most other modern supersports, or at least, not in stock form.

Emissions and, in particular, noise restrictions reduce its overall power output substantially. Simply adding a fuel controller, or getting an ECU reflash post-purchase unlocks enough power to pit it against bikes like the aforementioned Honda, the Yamaha YZF-R7, Suzuki GSX-8R and Kawasaki’s own Ninja 650. It becomes a very different animal, but it will most certainly void your warranty, and depending on where you live, potentially make it illegal to ride.

Rivals

• Honda CBR650R
• Yamaha YZF-R7
• Suzuki GSX-8R

The Ninja ZX-4R Offers Unrivaled Performance In Its Class

Power: 56 Horsepower

Kawasaki

The thing is, there just isn’t anything quite like it on the market. If you were to keep it completely stock, in its rather muted state of tune, it would still wipe the floor with any other 400cc motorcycle currently on the market. In that regard, it is peerless, but that isn’t precisely what Kawasaki was going for here. It exists for two very specific niche buyers.

The first is somebody looking for an affordable inline-4 motorcycle. In essence, a bike that is just really fun to ride, even at street legal speeds. No matter what speed you are at, it will always feel faster with that engine screaming through each of the gears. For that kind of buyer, the overall horsepower won’t really matter, and it is all about the ownership experience. The second is going to be somebody who wants a modern track bike. While it is easy enough to find a used sports bike to convert into a track toy, that certainly won’t be for everyone.

In many respects, taking this to the track just makes sense. While the official horsepower figure will always be 56 horsepower, it really doesn’t take much to unlock a lot more. An aftermarket tune – simply the stock tune in the rest of the world – bumps the power figure up to 80 horsepower. Very nearly double what other 400cc bikes will be making, without any other 'non-Kawasaki' mods.

Engine Specifications

The Ninja ZX-4R Is The Ultimate Entry-Level Track Bike

Your Ticket To Track Day Fun

Kawasaki

This isn’t necessarily a case of bringing a gun to a knife fight. The ZX-4R will most likely get bumped to a different class depending on which track you go to. It is more a case of this being an ideal tool for the job. The ZX-4RR (shown above) might even be a better starting point for some, but for most track enthusiasts, it is expected that some changes will be necessary and the uprated suspension might not be the setup you are after.

The stock suspension on the ZX-4R is adequate, especially for those just starting out. In fact, it serves as the ideal platform to start with – bone stock – then slowly modify as you hone your skills. With such a big aftermarket for suspension components, starting with a simple setup might actually be better. So you can get an idea of what kind of upgrade will suit your riding style at a later stage.

2024 Ninja ZX-4R vs Ninja ZX-4RR

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With modern supersports all getting heavier and more expensive, this provides budding racers with an ideal alternative. Its lightweight steel trellis chassis, sourced from the ZX-25R, offers the perfect balance between rigidity, flexibility and affordability. Everything you need is there, and unlike any similarly priced used options, this has all the modern amenities that will save you from a spill while you are still learning the ropes.

Chassis And Suspension Specifications