YZF-R6 vs ZX-6R Acceleration and Top Speed
The Supersport 600 class is no longer.
Manufacturers have largely abandoned it due to changing market factors and evolving rider tastes.
You can still buy a few supersport 600 motorcycles new in some markets today, but they are receiving little to no further development and are gradually being discontinued.
Instead, manufacturers are focusing on slightly less powerful machines that still deliver strong performance while being more affordable and far more practical for everyday use.
That said, Supersport 600s are far from dead. There remains strong interest from both new and experienced riders, and the second-hand market is full of excellent examples offering outstanding value for money.
Two of the most popular models in the class for many years have been the Yamaha YZF-R6 and the Kawasaki ZX-6R (636).
YZF-R6 vs ZX-6R 636 Dyno curve
– ZX-6R – YZF-R6
Both motorcycles compete in the same supersport class, but the Kawasaki ZX-6R has a 37 cc capacity advantage over the Yamaha YZF-R6.
While that difference may sound small, it has been a major selling point for the Kawasaki ZX-6R 636 over the years.
One of the main criticisms of supersport 600s is how extremely focused and radical they have become.
Engines are revved ever higher to achieve headline peak power figures, often at the expense of usable power and torque lower down the rev range.
Kawasaki took a sensible approach by adding extra capacity to the ZX-6R while continuing to sell the 599 cc version alongside it for homologation and racing eligibility.
Yamaha, by contrast, chose not to offer a larger version of the YZF-R6, preferring instead to extract more revs and peak power from the existing 599 cc engine.
Thanks to Yamaha’s efforts, the YZF-R6 has become the most successful supersport 600 on the racetrack.
However, many of its track strengths have sometimes proved to be liabilities on the road.
Yamaha claims 123 horsepower for the latest YZF-R6, a figure that is slightly down on previous versions due to ever-stricter noise and emissions regulations.
Kawasaki claims 126 horsepower at the crank and 52 ft-lb of torque for the ZX-6R, with the latest model also producing slightly less than earlier versions for the same reason.
On the dyno, the Kawasaki ZX-6R delivers an impressive 117 horsepower at 13,500 rpm and 48 ft-lb of torque at 11,500 rpm.
These figures match or even exceed the output of many 1,000 cc V-twins and 750 cc four-cylinder superbikes from the late 1990s and early 2000s – truly remarkable for a 600
.The Yamaha YZF-R6 trails by 7 horsepower, producing 110 horsepower at 14,800 rpm and 42 ft-lb of torque at 11,100 rpm.
That is still an excellent result considering its smaller engine capacity.
When comparing the dyno curves across the full rev range, the Kawasaki not only makes significantly more peak power and torque, but it also dominates throughout the entire rpm range.
This substantial advantage gives the ZX-6R 636 a clear edge in real-world riding on the road.
The extra torque often allows the Kawasaki to pull harder in a higher gear or match the Yamaha’s acceleration from as much as 2,000 rpm lower in the rev range.
The Kawasaki’s power curve is noticeably smoother, with fewer peaks and troughs, while the Yamaha’s curve shows multiple small flat spots and surges that are less ideal.
Although these imperfections are less obvious on the road, the dips and surges are still noticeable and create flat spots in acceleration.
To make real progress on the YZF-R6, the engine needs to be kept above 9,000-10,000 rpm.
Below that, it feels lacking compared with its rivals – and even in isolation.
While the Yamaha YZF-R6 is undoubtedly one of the fastest supersport 600s ever built, it is also the peakiest and demands the most commitment from the rider in terms of engine revs and frequent gear changes.
By comparison, the Kawasaki ZX-6R feels like stepping onto a 750 after riding the R6.
It drives exceptionally well from as low as 6,000 rpm, making it one of the best – if not the best overall engines in the 600 cc supersport class, even if Kawasaki did “cheat” a little with that extra 37 cc.
YZF-R6 vs ZX-6R 636 in gear thrust
– ZX-6R – YZF-R6
The graph above shows the torque curve multiplied by the gear ratios.
The lines represent the actual acceleration you feel when you open the throttle.
The great advantage of in-gear thrust curves is that they reveal exactly what performance the engine delivers in any gear and at any road speed.
One engine may produce less torque than another, but if it runs lower gearing it can still be more accelerative because it generates more thrust at the rear wheel.
Looking at a dyno curve in isolation only gives you raw peak numbers; it does not tell the full story of how the bike actually performs on the road.
The thrust curve, by contrast, always follows the same basic shape as the torque curve, although the lines become less condensed (more spread out) in the higher gears, as you can see above.
When you examine the graph, it is clear that the Kawasaki ZX-6R dominates in every gear and at every speed when comparing the same gear.
There is not a single point where the Yamaha YZF-R6 matches – let alone beats – the ZX-6R 636.
This is particularly impressive because the Kawasaki is actually running slightly taller gearing across all six gears.
Despite this, its substantial torque advantage is more than enough to deliver greater thrust and stronger acceleration in every gear.
The ZX-6R engine is so strong that, from 70 mph in sixth gear, it can even out-accelerate the YZF-R6 when the Yamaha is in fifth gear.
In short, there is nowhere the Yamaha YZF-R6 can match the Kawasaki ZX-6R on a gear-for-gear basis.
What the thrust curves clearly demonstrate is that, in any gear and at any speed, if you were having a roll race with friends, the Kawasaki ZX-6R would be the more accelerative motorcycle.
YZF-R6 vs ZX-6R 636 speed in gears at 5000 rpm
| Speed at 5000 rpm | ZX-6R 636 | YZF-R6 |
| Speed 1st Gear | 25.4 mph | 24.5 mph |
| Speed 2nd Gear | 32.8 mph | 31.6 mph |
| Speed 3rd Gear | 39 mph | 38 mph |
| Speed 4th Gear | 45.1 mph | 43.8 mph |
| Speed 5th Gear | 50.8 mph | 49.2 mph |
| Speed 6th Gear | 55.6 mph | 55 mph |
The Kawasaki ZX-6R 636 dominates on the dyno and in in-gear thrust, but the gap narrows when it comes to outright acceleration through the gears.
Even so, the ZX-6R 636 still holds a slight edge when it really matters.
The sprint from 0–60 mph is extremely close, with the Kawasaki just a few bike lengths ahead.
The ZX-6R 636 achieves a blistering 3.17 seconds, while the Yamaha YZF-R6 is a mere two hundredths of a second behind at 3.19 seconds.
These times are on par with many current 1,000 cc superbikes – an impressive achievement for 600 cc machines.
Both bikes are relatively easy to launch, although they will happily lift the front wheel hard in first gear.
The Yamaha YZF-R6 is far more prone to bogging down if you don’t use enough revs or slip the clutch effectively.
To get the best launch, the R6 really needs to be kept near its peak torque point of around 11,000 rpm.
Anything below 8,000 rpm carries a higher risk of the engine bogging if the clutch is fully engaged.
By contrast, the Kawasaki ZX-6R 636 is noticeably easier and more forgiving to launch.
While it is still best to slip the clutch around peak torque, you can let the revs drop as low as 7,500 rpm without a significant penalty to your elapsed time.
The Kawasaki maintains its slight advantage to 100 mph, reaching the mark in 6.02 seconds compared with the Yamaha’s 6.08 seconds.
Although the ZX-6R is marginally quicker to 60 mph and 100 mph, the two bikes are very closely matched in outright acceleration.
For most riders, the Kawasaki will feel quicker simply because its more flexible engine makes it easier to launch consistently.
Beyond 100 mph, the ZX-6R 636 completes the quarter-mile in 10.74 seconds at a terminal speed of 134 mph.
The Yamaha YZF-R6 is only a fraction behind at 10.89 seconds with a terminal speed of 133 mph.
At this point, the difference is negligible and will largely come down to rider weight and skill.
Kudos to the Yamaha YZF-R6 for staying so close to the Kawasaki despite the less favourable on-paper numbers.
As speeds rise, however, the Kawasaki’s advantages begin to tell. While the 0–130 mph times remain very close, the ZX-6R pulls ahead to 150 mph in 15.42 seconds, compared with the R6’s 16.12 seconds.
From there, the gap widens significantly: the Kawasaki reaches 0–160 mph in 22.68 seconds, while the Yamaha takes 32.92 seconds – almost 10 seconds slower.
Top speeds are also very close, with the ZX-6R 636 reaching 164 mph and the YZF-R6 managing 161.3 mph.
The Yamaha may have slightly better aerodynamics, but the Kawasaki’s extra seven horsepower at the top end is enough to give it the advantage.
In summary, the two bikes are extremely close up to around 130–150 mph, with the ZX-6R 636 gradually pulling away thereafter.
The biggest real-world difference is Kawasaki’s massively more flexible and usable engine.
With modifications such as a full exhaust system and ECU flash, both can exceed 130 horsepower at the rear wheel, and the performance gap narrows even further.
YZF-R6 vs ZX-6R 636 Acceleration through the gears
– ZX-6R – YZF-R6
| Speed | Kawasaki ZX-6R Acceleration | Yamaha YZF-R6 |
| Time | Time | |
| 0-10 mph | 0.41 | 0.52 |
| 0-20 mph | 0.91 | 1.04 |
| 0-30 mph | 1.57 | 1.57 |
| 0-40 mph | 2.12 | 2.1 |
| 0-50 mph | 2.64 | 2.64 |
| 0-60 mph | 3.17 | 3.19 |
| 0-70 mph | 3.71 | 3.73 |
| 0-80 mph | 4.41 | 4.44 |
| 0-90 mph | 5.09 | 5.15 |
| 0-100 mph | 6.02 | 6.08 |
| 0-110 mph | 6.96 | 7.08 |
| 0-120 mph | 8.31 | 8.45 |
| 0-130 mph | 9.78 | 10.04 |
| 0-140 mph | 12.02 | 12.53 |
| 0-150 mph | 15.42 | 16.12 |
| 0-160 mph | 22.68 | 32.92 |
| 60-130 mph | 6.60 | 6.86 |
| 100-150 mph | 9.40 | 10.04 |
| SS/QM | 10.74 @ 134 mph | 10.89 @133 mph |
| SS/KM | 19.77 @ 157 mph | 19.92 @ 154 mph |
| SS/Mile | 28.14 @ 162 mph | 28.46 @ 159 mph |
| Top Speed | 164 mph | 161.3 mph |
