The Ninja 400 can accelerate from 0-60 mph in 4.15 seconds
Kawasaki’s Ninja 400 was introduced in 2018 and replaced the hugely capable and popular Ninja 300, which was itself a replacement for the Ninja 250.
The introduction of the Ninja 400 was likely Kawasaki’s response to Yamaha’s YZF-R3, among many other factors.
That machine had the edge on the Ninja 300. It was a little more powerful, thanks to its slightly larger engine, which meant its engine performance and straight-line speed were, and remain, superior.
Performance matters to many riders, and on paper, the YZF-R3 had the edge over the Ninja 300. So Kawasaki had to respond. No doubt an influencing factor that pushed Kawasaki to design a big-bore version of their Ninja 300 was the ever-evolving motorcycle learner laws.
The Ninja 400 was also a response to competitors offering faster and more powerful alternatives.
Kawasaki’s Ninja 400 engine was generally much the same as the 300 it replaced, but it received a significant capacity boost. This capacity increase jumped from 296 cc on the Ninja 300 to a much beefier 399 cc for the new Ninja 400.
A 103 cc jump might not sound like a lot, but for a small-capacity motorcycle, it represents a massive 35% increase in engine size over the Ninja 300.
The Ninja 400 has a peak claimed power (which varies by market) of 49 hp at the crank. This compares to 35 hp at the crank for the Ninja 300 and is a welcome boost for Kawasaki fans and Ninja 300 owners looking to upgrade.
That jump in power is a 40% increase, which is significant, and all from that extra capacity.
Not surprisingly, torque is also up 40% over the Ninja 300, to a claimed 28 lb/ft. The larger engine made the Ninja 400 more tractable and less dependent on high revs and frequent gear changes to make effective overtakes compared to the Ninja 300.
As a result, the Kawasaki Ninja 400 almost has that big-bike feel, thanks to its larger engine. The Kawasaki Ninja 300, despite being a quick little bike, never had that big-bike feel.
Kawasaki Ninja 400 Dyno Curve
As you can see from the dyno curve above, the new Ninja 400 produces a very impressive 44 horsepower at 10,500 rpm. This rear-wheel figure is not far off Kawasaki’s claimed 49 hp at the crank.
As a rule, when power is transferred from crank to wheel, the average chain-driven motorcycle loses around 10-12% of its power through transmission losses.
This loss is caused by friction and heat in the engine, as well as the energy required to spin the rear wheel and tyre. These factors all contribute to the difference between crank and rear-wheel horsepower figures.
In terms of power, the Ninja 400 sits right next to Honda’s CBR500R. This is surprising considering the Ninja 400 has a smaller-capacity engine.
It also matches up closely with KTM’s fiery little RC 390.
What is also impressive is that the little parallel twin produces more than 40 horsepower from 8,000 rpm all the way to 12,000 rpm.
Kawasaki Ninja 400 in-gear acceleration
That wide spread of power means the Ninja 400 is not so dependent on being in the “right” gear.
A rider can still make good progress without needing to scream the engine all the way to 12,000 rpm, something that is necessary with some competitors.
Selecting the correct gear is a constant reality when riding the smaller Ninja 300. While fun on occasion, constant gear changes can become tiring, especially when trying to keep up with friends on faster motorcycles on roads that require frequent speeding up and slowing down.
This wide spread of power also allows you to hold gears longer in corners because there is ample drive from as low as 6,000 rpm.
Additionally, the engine is relatively flexible. From just 3,000 rpm, the Ninja 400 produces more torque than the Ninja 300 does at its peak. It even beats the YZF-R3 in this regard.
Despite the Ninja 400’s engine punching above its weight, keeping the engine in the higher rpm range is more effective if you want to make the fastest progress against larger motorcycles.
Ideally, revs should be kept no lower than 6,000 rpm, though from 7,000 rpm onward the engine really comes alive and delivers strong acceleration.
Ninja 400 in gear speeds at 5000 rpm
| Speed at 5000 rpm | Ninja 400 |
| Speed 1st Gear | 18.8 mph |
| Speed 2nd Gear | 26.8 mph |
| Speed 3rd Gear | 34.1 mph |
| Speed 4th Gear | 41.4 mph |
| Speed 5th Gear | 47.8 mph |
| Speed 6th Gear | 53.2 mph |
Due to the engine size and relatively low gearing, rpm will always be fairly high in most real-world situations compared to larger-capacity motorcycles.
That’s simply the reality of riding a sub-500 cc bike, unless it’s a long-stroke single-cylinder engine.
For a small engine, the Kawasaki Ninja 400 is not particularly buzzy. For example, at 70 mph in sixth gear on the highway, it turns around 6,600 rpm.
By comparison, a Yamaha YZF-R6 sits at around 6,400 rpm at the same speed, while its smaller sibling, the Ninja 300, is noticeably more frantic at about 7,600 rpm.
You can comfortably use sixth gear at 70 mph on the Ninja 400 and still overtake effectively. Try the same on the Kawasaki Ninja 300, and you’ll usually need to drop a gear, especially into a headwind or on any kind of incline.
This meatier power delivery and less frantic engine character are what give the Ninja 400 its “big bike” feel. Its performance numbers back this up as well.
Kawasaki Ninja 400 Top Speed and Acceleration Review
It’s still a little slower than some of its bigger-capacity rivals, such as the MT-07 and YZF-R7, though it remains impressively close considering the substantial displacement disadvantage the Ninja 400 gives away.
For any petrolhead, a sub-5-second 0-100 km/h (or 0-60 mph) time is seriously quick by any standard.
The Kawasaki Ninja 400 is as fast as – and in some cases faster than – many hot hatches and sports cars from the past and present.
A lot of smaller-capacity motorcycles in this class can accelerate to 100 km/h in around 6 seconds or less.
The Ninja 300 manages approximately 5.4 seconds from 0-60 mph, but as speeds increase, its acceleration tails off more noticeably due to its lack of power.
It is also very important to note that on smaller-capacity motorcycles with less than 50 horsepower, weather and road conditions play a much larger role in the elapsed times and terminal speeds achievable.
Perfect conditions are often needed for the best results with modest power outputs.
With its larger engine, the Ninja 400 remains peppy even above 60 mph, as the figures clearly show.
From 0-100 mph, it takes 11.8 seconds — quicker than many would expect from the Ninja 400.
The Kawasaki Ninja 400 is a full 6 seconds faster to 100 mph than its smaller 300 sister.
Rolling acceleration from 60 mph to 100 mph through the gears takes 7.75 seconds on the Ninja 400, while the Ninja 300 lags far behind with a leisurely 12.8 seconds.
To put this into perspective, the Ninja 400 can reach 100 mph from a standing start faster than the Ninja 300 can accelerate from 60 mph to 100 mph.
The Ninja 400 covers the standing-start quarter mile in 12.98 seconds at 102 mph.
The terminal speed is slightly reduced by an inconvenient gear change right at 100 mph, about 40 metres from the finish line.
Even so, the Kawasaki Ninja 400 still beats one of its closest KTM rivals and is a fraction quicker than its naked Z400 sister, thanks to the aerodynamic advantage of its full fairing.
Kawasaki Ninja 400 Top Speed is 116.7mph
With smaller-capacity, lower-power motorcycles, reaching true top speed usually requires a full jockey tuck and a very long stretch of tarmac.
To achieve its maximum speed of 116 mph (186 km/h), the Kawasaki Ninja 400 needs around 100 seconds and approximately 4.8 km.
That said, this is not the fairest way to judge the bike. The Ninja 400 can reach 111 mph (180 km/h) in just 20 seconds and roughly 750 metres from a standstill.
The final few mph simply demand a disproportionate amount of time and distance.
The Kawasaki Ninja 400 reaches its top speed in fifth gear, just below the redline, if you let the revs build long enough. Engaging sixth gear makes no difference, as the bike on test could not pull sixth all the way to the redline, which would theoretically equate to 129.8 mph (209 km/h).
If the mirrors were removed and a taller screen fitted for better wind protection in a tuck, a few extra mph might be possible.
Most Kawasaki Ninja 400 owners add bolt-on modifications to boost power and performance. A good exhaust system, proper fuelling, and a performance air filter could push the little Ninja to a real-world top speed of around 124 mph (200 km/h).
Some heavily modified race versions with bolt-ons have even been clocked at 130 mph — which is remarkable for a 400 cc bike.
Not everyone will achieve top speeds and times like this because the Ninja 400 is still a relatively low-powered motorcycle.
To achieve optimum performance, the stars really must align. The rider needs to be light (65 kg or less), and conditions must be close to perfect. A 10-20 kg difference in rider weight, combined with even a moderate headwind or unfavourable conditions, will significantly affect acceleration and top-speed runs.
After all, the Kawasaki Ninja 400 produces just over 40 horsepower at the rear wheel, so it is affected far more by rider weight and daily conditions than higher-powered bikes.
These variables do not impact a much more powerful motorcycle to the same extent as a sub-50 horsepower machine like the Ninja 400.
The Ninja 400 is an exceptionally good learner motorcycle. It is economical, has cheap insurance, and remains a very capable sportbike even for more experienced riders.
Either way, the Kawasaki Ninja 400 delivers good straight-line performance and is a significant step up over the Ninja 300.
You may also be considering other competitors in the class, such as the YZF-R7, the full-power Honda CBR650R, the restricted CBR650R, or the smaller CBR500R.
All of these fit into the same diverse entry-level sport motorcycle segment as the Kawasaki Ninja 400.
To make things even more interesting, Kawasaki has introduced the ZX-4RR to shake up the class.
The ZX-4RR adds another layer of sibling rivalry for the Ninja 400, on top of the competition it already faces from the Ninja 650 and Ninja 300.
Kawasaki Ninja 400 vs Yamaha YZF-R3 HERE
| Kawasaki Ninja 400 Acceleration | |
| Speed | Time |
| 0-10 mph | 0.62 |
| 0-20 mph | 1.24 |
| 0-30 mph | 1.87 |
| 0-40 mph | 2.49 |
| 0-50 mph | 3.28 |
| 0-60 mph | 4.15 |
| 0-70 mph | 5.39 |
| 0-80 mph | 6.83 |
| 0-90 mph | 8.93 |
| 0-100 mph | 11.90 |
| 0-110 mph | 17.51 |
| SS/QM | 12.98/102 mph |
| SS/KM | 25.12/114 mph |
| SS/Mile | 36.73/115 mph |
| Top Speed | 116.7 mph |
Kawasaki Ninja 400 Specifications
| Kawasaki Ninja 400 | |
| Engine | |
| Engine type | 4-stroke, 2-cylinder, DOHC, liquid-cooled |
| Capacity | 399 cc |
| Bore x stroke | 70.0 x 51.8mm |
| Compression ratio | 11.5:1 |
| Maximum power | 49 HP 10500 RPM |
| Maximum torque | 28.0 lb-ft @ 8,000 rpm |
| Lubrication system | Wet sump |
| Clutch type | Slipper and self-servo wet multiplate clutch with hydraulic control |
| Ignition system | Digital Advance |
| Starter system | Electric |
| Transmission system | Constant Mesh, 6-speed |
| Final transmission | Chain |
| Chassis | |
| Frame | Semi-double cradle, high-tensile steel |
| Front suspension system | 41mm Telescopic fork/4.7 in |
| Rear suspension system | Bottom-link Uni-Trak®, swingarm adjustable preload/5.1 in |
| Front brake | 310mm semi-floating single disc |
| Rear brake | 220mm single disc |
| Front tyre | 110/70×17 |
| Rear tyre | 150/70×17 |
| Dimensions | |
| Wheelbase | 1,370 mm |
| Wet weight (including full oil and fuel tank | 168 kg |
| Fuel tank capacity | 14 litres |
