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Scorpion Merchandise
Ninja 400 / 250

Kawasaki Ninja 400 / 250
2018 - 2024

Half System / Serket Taper / Brushed Stainless / RKA121SEO

Serket Taper Slip-on

RRP $484.66 | Part No: RKA121SEO


Silencer Style

Silencer Finish

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Lifetime Warranty
Brushed Stainless Serket Taper
Not Homologated
42 HP
+ 1.5 HP


One of the big four Japanese motorcycle producers Kawasaki has a history stretching back to the 1960’s producing many innovative models over the years including the world’s first air cooled, DOHC, in-line four engine in 1972. The 80’s saw the release of the first of their iconic Ninja range which have gone on to become one of the most sought-after marques. Motorsports has played a big part in their history most notably in World Superbikes where they’ve won numerous world championships over the years. Scorpion also have a rich history in producing performance exhausts for many Kawasaki powered race teams over the years ensuring true track to road technology transfer.

Our leading technicians have developed through rigorous trial and testing a slip-on and full system for the Kawasaki Ninja 400. Using dynamometer development combined with track to road technology Scorpion exhausts are cutting-edge performance products. Our branding is a hallmark for precision engineered exhausts, fabricated using premium high thermal tolerance T304 motorsport grade stainless steel tube that will endure through the harshest of conditions.

Want a little more power from your motorcycle? Our half-system is the perfect compromise, leaving the factory catalysts (where fitted) in place and bolting directly to the OEM system. Scorpion's half-systems are designed for improved gas flow and sound, perfect for those using their bike as a daily.

For those riders wanting all-out performance our racing inspired full system is the answer, with an improved upswept angle for the rear silencer giving riders an improved leaning angle clearance when on the track. This system has been developed with de-cat pipework which removes the bulky OE catalyst resulting in unobstructed gas-flow, which is perfect for those riders pushing the boundaries of exhaust performance. Our high-flow header pipes also eliminate excessive back pressure which can occur when your bike's engine expels exhaust gasses in restrictive OEM pipework. (For closed circuit use only.)

Our racing inspired full system was originally designed for the Affinity Sports Academy Kawasaki team. They had a fantastic 2022 racing season, which saw rider James McManus take home the British Junior Supersport champion title. This was all achieved whilst running our full race Serket Taper system, showing our track-to-road programme in action!

The OE system doesn’t require cutting and as a result allows for straightforward installation when using our official Scorpion fitting guides. Riders will be able to indulge in a more tantalising tone with a much deeper sportier acoustic range that will epitomize the enduring quality of this product throughout its lifetime of service.

High-flow silencer, weight reduction and large bore pipework shaped using CNC Mandrel bent construction are all key contributors to improved performance. By allowing a greater flow of exhaust gas our exhausts provide a sharper throttle response and increase in bhp. With all these improvements packed into our exhausts it’s no-wonder that upgrading with Scorpion has been described as transforming the riding experience!

Our signature silencers are instantly recognisable due to popularity with motorcyclists worldwide, maintaining the unchanging standard of unrivalled Scorpion build-quality. The silencer is not only one of the most technically intricate components of the exhaust system but one of the most visually eye-catching. For this reason, we offer a selection of silencer styles and finishes depending on motorcycle model and manufacturer.

The Ninja 400 slip-on and full system can be fitted with the Serket Taper style silencer finished in either brushed stainless, titanium or carbon fibre. Red Power style silencer can be finished in brushed stainless, titanium or black ceramic. Finally, we’re offering our hardcore racing inspired RP1-GP silencer finished in lightweight carbon fibre.


Nothing beats that feeling of knowing you’re riding on an authentic race grade product and Scorpion pretty much pioneered the concept of technology transfer by sharing everything which works on the track with you the rider.

Ultra-light weight materials, hours spent on the dyno and durability testing is at the heart of our extensive development program. From the moment you fire up your new Scorpion, the heart begins to race, and adrenalin starts to flow. Upgrade to Scorpion and bring out the racer in you.



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Technical Data

Technical information for RKA121SEO
Product Type Half System
Fitment Years 2018 - 2024
Fits To OEM Only
Model Fitment Ninja 400
Shipping Dimensions 58cm x 23cm x 16cm
Closed Circuit Product Yes
OEM Scorpion Change
Power Difference 40.5 BHP 42 BHP +1.5BHP
Weight Difference 4.12 KG 1.98 KG -2.14 KG


Spares for RKA121SEO | Please note these are not required when purchasing a new product.
Type V Serket Db Killer Z038.10043

Type V Serket Db Killer Z038.10043



Fitting Kit - Ka1015 / Rka121

Fitting Kit - Ka1015 / Rka121



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Since 1992, we have been designing, developing and manufacturing stainless steel performance exhausts in the heart of Derbyshire, UK.

  • Scorpion Redpower Ltd, Unit 3 High
    Holborn Road, Codnorgate Business Park,
    Ripley, Derbyshire, DE5 3NW
Rated Excellent
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