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Removing The Leash – The Kawasaki ZX-4RR Gains More Power With The TST WORX Tune.
Kawasaki’s introduction of the Ninja ZX-4RR to the North American market was something that only a few of us in the industry expected. Not because we didn’t want it to come here – that’s far from the case. We looked at it from a practical standpoint and the potential return for Kawasaki, and that perspective cast some doubts on it ever landing on our shores. As more manufacturers have moved to twins and triples, the high-revving inline-four engine that is a staple of the supersport class has become a bit of a rarity on dealer floors. We can all thank the ever-restricting emission regulations across the globe and rising manufacturing costs for their scarcity, but that is a discussion for another time. With all of that in mind, I think we all kind of thought that there wasn’t a market for a bike meeting these specs, or at least not one that a major manufacturer was willing to invest in. Thankfully though, we were wrong.
Kawasaki’s dedication to the supersport market has outlasted that of their big four rivals. As Honda, Yamaha, and Suzuki have let their supersport models grow incredibly long in the tooth and even be restricted from certain markets due to failure to meet new emission regulations, Kawasaki continues to step up to the plate. Not only did they update their ZX-6R with new styling, technology, and engine components to meet those restrictions, continuing the supersport class into the modern era, but they also released a new model into the supersport category to which there is no competition. No other major manufacturer is making something like the Ninja ZX-4RR, and that boldness gains a lot of respect.
Now, due to the nature of the beast, the ZX-4RR had to come out of the factory with some heavy restrictions in place so that it would meet the strict emission requirements. We totally understand that and honestly, we’re just happy that all of the componentry is there for us to be able to unlock. Getting this bike is a bit like someone giving you a ramp for your bicycle and saying “Happy birthday kid, just remember you can only ride up and then slide back down the ramp, you shouldn’t ever go full speed and ramp your bicycle off of it and see how much distance you get wink wink“. And very much like a kid looking at a homemade ramp in their driveway…we wanted to go full speed right at the ZX-4RR.
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As soon as we got our very own KRT ZX-4RR on our WORX facility dyno, we began removing the restrictions to reveal the full performance of the OEM parts package. Without swapping a single OEM component on the ZX-4RR, we found that by simply removing the restrictions within the ECU and still keeping the bike well within safe parameters, we were able to gain a massive 32% in horsepower and torque, proving without a shadow of a doubt that this bike is sold on the floor as a neutered version of what it could be. The peak horsepower goes from 58.56 to 70.39 while the peak torque increases from 19.46 to 25.77. Peak numbers aren’t the main benefit, however, because after unlocking the ECU, you’ll notice that the power keeps climbing after 11,500 RPM, unlike the stock tune which falls flat. All that extra power provides you with the push needed to keep accelerating in the straight and land your race boots on the podium.
Some would think that unlocking the ECU and seeing those types of gains is enough, but we are always chasing more power, and we saw the potential to gain even more. Before we developed a proper WORX tune, we wanted to see how some upgraded parts would improve the Unrestricted Flash. We specifically chose the Akrapovic full system exhaust, which happens to be for the ZX25R and is sold in other parts of the world, but mates perfectly with the ZX-4RR and provides impressive results with even more impressive sound. We also installed an MWR Race Air Filter for improved airflow going into the inline four while retaining excellent filtration performance.
After installing those two upgrades and flashing the ECU, we tossed it on the dyno for testing and found that the new parts do provide increases in performance when compared to the stock components. It’s easy to see why, as they are allowing more air in and out of the engine system, enabling more power potential through the combustion process. We charted this in green on the dyno charts.
Now that we have extra power potential, Alex went to work refining the fuel maps and other ECU parameters to take full advantage of those newly install components by developing our Stage 1 WORX Tune. After developing and testing the tune repeatedly, we found that we could reliably achieve a 43% increase in power and torque when compared to the stock components and stock tune, taking the peak horsepower from 58.56 to 76.02 and the peak torque from 19.46 to 27.80. These are insane power gains that you can rarely achieve with basic component upgrades and an ECU flash, making the ZX-4RR even seem like it really is a beast waiting to be unleashed.
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When looking at the dyno charts, you’ll notice that the stock tune restrictions really kick in at 11500 RPM when the power stops climbing and falls flat, preventing further acceleration. When you’re on the straight at your favorite track, the stock tune is literally holding you back after you reach that area of the powerband, but whether you go with our Unrestricted ECU Flash or our full WORX Stage 1 Tune, you’ll continue to climb and gain speed where you need it and have the tools to decrease your lap times.
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We know that many people want to know the top speed of the ZX-4RR, and we are happy to report that we reached 147.94 MPH on the dyno. We found that the dash of the Kawasaki is about 9% optimistic, reporting a higher number than what our dyno speed number was indicating. The dash reported 162 MPH as the highest number when recording the true 147.94 MPH on the run. Having a bit of a padding on your speed when looking at the dash isn’t always a bad thing, mostly for the street, but when you’re out on the track you want reliable numbers.
During testing at Roebling, Bart hit an indicated 132 MPH on the front straight with the Stage 1 WORX Tune, full Akrapovic Exhaust, and MWR Race Air filter. Our good friend Dan installed our Unrestricted ECU Flash while keeping the stock exhaust and achieved 121 MPH according to his GPS data while pushing his ZX-4RR at Jennings GP along the straight section after turn 2.
We fully intend to continue our tune development and keep testing, and assure everybody that we will be updating this article with new information as we discover it.
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With a bike as well put together as the Ninja ZX-4RR that already contains loads of potential, unlocking this type of power is capable of silencing critics and winning races. But let me let you in on a secret – we aren’t done yet, because there’s still even more potential left to take advantage of within the ZX-4RR inline four platform, and we are already working hard to achieve bigger gains, but you’ll have to stay tuned for more details on that project.
When it comes to flashing your ZX-4RR’s ECU, it’s very rare that something so easy to install can unlock this much power and provide these kinds of performance gains and provide such dramatic shifts to the power delivery. Typically, these kinds of gains come at the cost of thousands of dollars worth of parts upgrades, weight reduction efforts, and engine work. With the ZX-4RR all it takes is mailing in your ECU and then plugging it right back in again to feel the immediate effects of what removing the leash on the beast feels like.
Want to learn even more about this tune and how to send in your ECU to be flashed? Click HERE for even more details and watch the video below.
