Kawasaki KX450F: Evolution and Rider Feedback

The Kawasaki KX450F: A Deep Dive into its Evolution and Rider Experience

The motocross world is a fiercely competitive arena, with manufacturers constantly striving to produce the ultimate 450cc machine. In 2017, this race for supremacy intensified with Honda's release of the all-new CRF450R, aiming to unseat the reigning champions like Yamaha's YZ450F and the formidable European contingent led by KTM's 450 SX-F and Husqvarna's FC 450. Amidst this intense competition, Kawasaki's KX450F, having received a significant overhaul in 2016, saw only revisions for 2017. This article delves into the KX450F's journey, examining its performance, rider feedback, and how it stacked up against its contemporaries.

A Comparative Shootout: The 2017 450cc Motocross Field

To truly understand the KX450F's standing, it's crucial to place it within the context of its peers. A comprehensive test day was organised at Sunrise MX Park, with a follow-up at the challenging Glen Helen Raceway. The evaluation criteria were rigorous, encompassing Engine Performance, Suspension Performance, Handling, Braking Performance, and Ergonomics. Each machine was also scrutinised for its price, features like electric start and engine management, and overall 'cool factor'. A diverse range of riders, from seasoned professionals to intermediate amateurs and even novice testers, provided their insights, ensuring a well-rounded perspective.

Engine Performance: The Heart of the Matter

Engine performance is paramount in the 450cc class, where power output often exceeds 60 horsepower. Manufacturers leverage sophisticated fuel injection and adjustable mapping to deliver usable power. Let's examine how the KX450F performed:

Honda CRF450R: A Powerhouse Reimagined

Honda's 2017 CRF450R engine was a complete revamp, boasting a new cylinder head, a higher compression ratio, and an improved downdraft intake for increased power. Riders universally praised its exciting power delivery, strong low-end punch, and enduring top-end pull. The engine was described as tractable and smooth, yet potent. However, some noted minor hesitations in the fuel injection and a tendency to flame out easily, making the optional electric start a desirable feature.

Husqvarna FC 450: A Tale of Two Perspectives

Sharing engineering with KTM, the FC 450 features electric start, traction control, and adjustable mapping. While mechanically similar to its KTM counterpart, rider feedback on the track revealed a different character. Some testers found it lacked outright speed and felt it required more effort to maintain pace, attributing this partly to a slightly slow throttle response and increased vibration. Conversely, novice riders found its power delivery deceptive, with strong, manageable roll-on that unleashed impressive torque when combined with the clutch.

Kawasaki KX450F: Lively but Lacking Top-End Snap

The 2017 Kawasaki KX450F, building on its 2016 redesign, featured a lighter, faster DOHC engine with new cases, improved intake, and higher-lift camshafts. While the engine felt lively, the majority of testers yearned for more aggressive power delivery. Comments included a flattening out too early in the rev range and less-than-optimal throttle response compared to rivals. The plug-in DFI coupler system for mapping adjustments was also a point of contention, with testers preferring handlebar-mounted switches for ease of use. Some riders noted that switching to the leaner coupler added throttle response but introduced deceleration popping.

KTM 450 SX-F Factory Edition: The Benchmark

The KTM 450 SX-F Factory Edition, while carrying a premium price tag, was lauded by all testers for its potent and refined engine. Riders appreciated its smooth yet aggressive power delivery, strong top-end performance, and the distinct differences between its selectable maps. While throttle response was noted as slightly dull by one rider, the sheer speed of the engine compensated. The hydraulic clutch and smooth shifting were also highlighted as positives.

Suzuki RM-Z450: Smooth but Outgunned

Despite not undergoing a redesign since 2015, the Suzuki RM-Z450 was praised for its fun, easy-to-ride DOHC engine with near-flawless throttle response and an agile chassis. However, its power output was consistently noted as being less competitive than newer models. Testers found it smooth but lacking the outright speed and aggressive character of its rivals, requiring more frequent shifting to maintain pace. For novice riders, however, its smooth and steady power delivery was a significant advantage.

Yamaha YZ450F: The Brute Force Contender

The Yamaha YZ450F, with its distinctive reverse-inclined engine, had long been a favourite for its powerful-feeling motor. It was described as a brute, offering strong power across the board with excellent throttle response. Riders found it easy to ride, capable of being short-shifted, yet still lively and fast. However, its aggressive nature could be tiring over a full moto, with some testers suggesting that while powerful, it lacked the manageability of the Honda, KTM, or Husqvarna.

The KX450F's Journey to 2019: A Significant Leap Forward

The provided information offers a stark contrast between the 2017 KX450F and its 2019 evolution. The 2019 model represented a significant leap, addressing many of the shortcomings of previous iterations.

Key Changes for the 2019 KX450:

• Engine: A lighter piston, plain bearings for the connecting rod, an 8.5mm forward cylinder offset, semi-dry sump crankcase, larger intake and exhaust valves with increased lift, finger-followers for valve actuation, a more downward-angled intake tract, a larger throttle body, a new injector design, a longer head pipe, a hydraulic clutch, and electric starting.
• Suspension: Showa coil-spring forks replaced the previous air forks, the front axle increased to 25mm, and the shock linkage and mounting were revised.
• Chassis: A new front brake master cylinder, a larger rear brake rotor, wider and more rearward footpegs, and narrower radiator shrouds.

2019 KX450F: Rider Impressions and Performance Analysis

The 2019 KX450 was met with enthusiasm for its improved powerband, which was described as reminiscent of earlier, more engaging KX450 powerbands. The engine offered super-responsive low-end power, a strong midrange, and a significant boost from 9400 rpm upwards. While dyno numbers suggested the 2018 model was stronger at lower RPMs, test riders overwhelmingly preferred the 2019's livelier feel and sense of urgency. However, the KX450 was noted to make 5 fewer horsepower than the 2019 CRF450 and ranked fifth in peak horsepower among the 2019 450cc field.

Coupler Confusion: The Green, Black, and White Maps

The plug-in ECU couplers for mapping adjustments continued to be a topic of discussion. The green coupler was deemed the best stock option, offering a significantly stronger performance than the black coupler, which mellowed out the entire rev range, sacrificing 1-2 horsepower. The white coupler offered no discernible difference in power compared to the stock green map, only a crisper feel.

Likes and Dislikes of the 2019 KX450F

What MXA Liked:

• Power: Described as incredibly lively, snapping to attention with the slightest throttle input.
• Handling: Once suspension was dialled in, it was a sweet-turning machine, even turning sharper when the forks were allowed to dive.
• Footpegs: The option to lower the footpegs by 5mm on the new chassis improved the feel.
• Tires: The switch to Dunlop MX3S tires was a welcome upgrade.
• Sound: The muffler design allowed it to pass both AMA Amateur and 2-meter-max sound tests, though the muffler itself was massive.

What MXA Disliked:

• Fork Springs: Considered too soft for faster riders, leading to bottoming issues. A simple solution involved using optional stiffer springs or a combination of stock and optional springs.
• Clutch: Despite the new hydraulic system, the clutch experienced slipping and fading. Stiffer clutch springs and the removal of the judder spring assembly were recommended fixes. The clutch lever also felt clunky.
• Rear Brake: The increased rotor size made the rear brake touchy with limited modulation. The pedal also had a limited adjustment range. Grinding the brake pads was suggested to improve feel.
• Airbox: Tool-less access was not achieved, requiring two different wrenches to remove the cover, and the filter cage design was awkward.
• Weight: While still the lightest Japanese 450, it was 10 pounds heavier than the KTM 450SXF, gaining 2 pounds from the previous year despite significant upgrades.
• Aesthetics: The styling remained largely unchanged from previous KX450 models.
• Bars & Grips: Preference for 7/8-inch bars persisted among some older testers, and the grips were shorter than usual.
• Levers: The clutch and brake levers had different profiles, with the clutch lever generally preferred.
• Battery: A micro-switch designed to prevent overheating could cause the engine to refuse to turn over until it cooled.
• Bottom Chain Roller: Rapid disintegration required frequent replacement, with a retrofit from the KX250 offering a more durable solution.
• Seat Bolt: The threaded plate for the seat bolt tended to fall out of the rear fender.
• Radiator Cap: A higher-pressure cap was recommended to prevent overheating.

The Verdict on the 2019 KX450F

The 2019 Kawasaki KX450F marked a significant return to form for the model. While it wasn't a perfect machine straight off the production line, it possessed strong fundamentals that made it a compelling option. The improvements in power delivery, handling, and overall chassis dynamics were substantial, making it a bike that riders could once again consider seriously. With some targeted modifications, particularly to the suspension and clutch, the KX450F could be transformed into a truly competitive machine.

Performance Parts and Accessories: Elevating the KX450F

For riders looking to further enhance their Kawasaki KX450F, a wealth of performance parts and accessories are available. Specialised shops offer packages focusing on areas like carburetion (though the KX450F is fuel-injected, tuning is still key), exhaust systems, and engine work. Reputable brands such as FMF, Wiseco, Pro-Circuit, and Renthal provide high-quality components designed to optimise performance and reliability, ensuring that the KX450F can indeed be taken to the next level without breaking the bank.

Frequently Asked Questions:

Q: How much torque does a 2018 KX450F have?
While specific torque figures for the 2018 model aren't detailed here, the 2019 model's dyno data indicated that the 2018 KX450F made 1.5 pound-feet more torque from 5000 to 9400 rpm compared to the 2019 model. The 2018 engine was generally favoured for its linear power delivery at lower RPMs.

Q: Will a Kawasaki KX450F break the bank?
While the initial purchase price of a motocross bike can be significant, the cost of ownership can be managed. Investing in quality performance parts and accessories from reputable brands can enhance the bike's performance and longevity. Many aftermarket companies focus on providing upgrades that offer good value and improve reliability, ensuring that riders can achieve their performance goals without excessive expenditure.

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