Kei Factory's Golden Full Exhaust System for the Kawasaki Z900RS: A New Era of Naked Customization

The first thing that catches your eye is the titanium full exhaust, instantly recognizable as a K-FACTORY product. However, it wasn't its beauty that truly surprised me. As soon as I started riding, I saw the high level of perfection in the new Z900RS and K-FACTORY's work, which polished it without compromising it.

⚫︎Photo: Koichi Otani

A "Golden Full Exhaust" Befitting the Fully Model-Changed Z900RS Series

The exhaust pipes, which form continuous curves extending from the engine, have no straight sections, suggesting highly efficient exhaust flow. The beautiful curvature fits the rounded design of the Z900RS Cafe, and its golden, brass-like luster stands out against the black-based 2026 model.

The Z900RS series underwent its first full model change in 2026, and its perfection is astounding. It features an electronic throttle with meticulously tuned fuel injection and ignition, and is equipped with a bi-directional quick shifter. Furthermore, the transmission and camshafts have also been modified. The close-ratio transmission pairs exceptionally well with the shifter, usable from 1500rpm, providing smooth riding regardless of the situation. Additionally, the maximum output has been increased by 5PS.

The highly perfected Z900RS series is a motorcycle that allows you to focus on reflecting your own aesthetics and values through customization, expressing yourself with free sensibility. K-FACTORY, which has been developing various custom parts since the debut of the Z900RS, offers many items for such self-expression.

The "CLR-RG+ Titanium Full Exhaust Hexagonal Silencer JMCA Certified (26-year model~) (¥374,000)" features a "Starting Gold" heat treatment. Other options include the "CLR-R+ Titanium Full Exhaust Round Silencer JMCA Certified (26-year model~) (¥308,000~)" with blue heat treatment, and exhaust pipes only, among various other mufflers.

For this feature, we borrowed demo bikes of the Z900RS Cafe and the CB1000F (introduced in a separate article) and went on a tour with Shoji Saito, a former Kawasaki test rider who now serves as K-FACTORY's test rider.

As soon as we started riding, we could feel the improved balance. While retaining the Z900RS Cafe's individuality, it felt lighter, and the bike's movements during braking, throttle operation, and weight transfer became more natural.

Shoji Saito (left), a former Kawasaki test rider who now develops parts and checks demo bikes for K-FACTORY. Born in 1953, he joined Kawasaki as a new graduate in 1972 and led the development of Kawasaki's flagship models. Despite his gentle smile, his evaluations of motorcycles are strict. He is a super-gentle veteran.

The "Radiator Side Cover Type II (¥28,600)" enhances the classical yet modern impression. It is available in aluminum polish and black anodized finishes. An "Engine Slider (¥12,980)" is also installed.

The etched stainless steel "Radiator Core Guard (¥19,800-¥22,000)" is available in four types. The photo shows Type C with the K-FACTORY logo. Other versions include Type A with the company logo, a plain stainless steel version, and a black specification.

The "Shine" and "Sound" Satisfy a High Desire for Ownership

"Riding the new model, I felt that the Z900RS series, which has evolved by thoroughly incorporating customer feedback, still has a lot of potential. K-FACTORY's Z900RS Cafe gives the rider a stronger sense of control, allowing them to operate it exactly as they intend. It's calm and well-balanced, making long rides less tiring. It feels like the inherent goodness of the stock bike is further enhanced by the customization. The dialogue between the rider and the bike becomes even more natural," says Saito.

"The stock model is so well-made that we want customers to enjoy customizing it to differentiate it from other bikes and to fulfill their desire for ownership. We especially felt the evolution during the development of the muffler for the 2026 model. We wondered if it would pass the tests with the specifications of the previous model, but it didn't. The data clearly showed that the engine was performing at a higher level with increased acceleration," says K-FACTORY representative, Kuwabara.

"It handles as I intend. The feedback is good too," says Saito. His deep love for Kawasaki remains strong.

Kawasaki clearly differentiates each model among the Z900RS, Z900RS Cafe, and Z900RS SE, which is a direct contributor to Kawasaki's strength. Equipping the Z900RS with a titanium full exhaust allows for authentic naked custom enjoyment, while the Z900RS SE can undoubtedly have its sporty capabilities dramatically enhanced.

The Z900RS Cafe is a very gentle cafe racer, as Saito mentioned. When you tuck into the small fairing and open the throttle, the high-pitched exhaust note unique to the titanium full exhaust resonates. It's as if the engine itself is filled with vitality. It strongly makes you realize that the rider and the bike are one, sharing the same time.

When you get off the bike and look at it, the muffler glints from different angles. You can't help but be mesmerized. Even when maneuvering it, it's slightly lighter than stock. It also satisfies the desire for ownership. The joy of replacing the muffler isn't just felt while riding; it visits you repeatedly.

The "Engine Hanger Set - Rear (¥52,800)" and "Front Sprocket Cover with Change Shaft Holder (¥28,600)" are available in metallic silver and black metallic.

The "Handle Clamp (¥10,450)" is machined from duralumin, adding a luxurious feel to the cockpit. Available in metallic silver and black metallic.

Build Your Own Original Custom Bike

The more I rode, the more I realized how well the Z900RS pairs with customization. Saito was also very impressed.

"The performance is already sufficient. In the past, we were desperately trying to get just one more horsepower from production bikes, but it's different now. Customization used to be about saying 'change the muffler and gain X horsepower,' but now, with nowhere to fully open the throttle, fewer people say that. What's more important is ease of handling, lightness, and appearance. The enjoyment of gradually making the bike your own with small parts is also great. Honda has also released the CB1000F, and it would be great if naked bike customization becomes more popular," says Saito.

The "Frame Plug (¥7,150)" covers the pivot area of the frame and prevents dust and water from entering the frame holes. The "Reservoir Tank Cap M-N (¥5,720)" is ideal for dress-up.

K-FACTORY offers a wide range of dress-up parts machined from aluminum for easy enjoyment.

The "Front Axle Slider (¥9,900)" made of Delrin helps minimize damage to your beloved motorcycle in case of a minor fall or tip-over.

The way we enjoy naked bikes has changed significantly. The Z900RS series is no longer just a bike for core Kawasaki fans. More and more people are enjoying it as a uniquely Japanese neo-classic style with their own free sensibility. A new world is definitely unfolding there. Customization is what adds further originality to that free sensibility.

Furthermore, in recent years, the used Z900RS market has become robust. More people are opting to spend on customization by keeping the vehicle price down. This trend may become even stronger with the full model change of the Z900RS series.

With the increasing sophistication of electronic controls in naked bikes to meet regulations and the high level of perfection in stock models, the demands of customization are gradually changing. That's why K-FACTORY doesn't just chase performance. It offers flowing exhaust pipe curves, deep heat colors meticulously applied by craftsmen, the quality feel of machined aluminum parts, and a ride that makes the dialogue with the rider more natural.

Respecting the perfected Z900RS and further refining its appeal – that is the brand philosophy of K-FACTORY.

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