One of Kawasaki’s underplayed machines, the KFX 400, was among the first four-wheelers to revolutionize the ATV industry by introducing 4-stroke power mills. Unknown to many, this paved the way for present-day sport quads that take the racing scene by storm.
The Kawasaki KFX400 is a nimble sport quad that resulted from the joint effort of Kawasaki and Suzuki in 2003. A replica of the QuadSport 400, this race machine featured a 4-stroke 398-cm3 engine, 85-mph top-end speed, excellent braking system, electric start system, and sporty aesthetics.
The KFX 400 may have taken a back seat since. But with its contributions to 450-cc speed demons, it certainly takes the forefront. Read on and learn more about this four-wheeler.
The Ultimate Do-It-All Machine
Before the advent of 450-cc thoroughbred racers, 400-class 4x4s like the Kawasaki KFX 400 dominated the sport riding scene. No wonder why it did – the KFX’s sporty styling, unparalleled agility, and extremely durable power mill placed it on the pinnacle of race machines.
But with recent-decade developments making 450-class quads reign supreme in this category, the KFX400 has succumbed into second place and defaulted into a trail tamer.
While many see this as a form of regression, it is one of the greatest strengths of the 4×4. It is not too often that four-wheelers can pride themselves on being good hybrid models.
With the 400-cc machine, owners get to experience the joy of riding tirelessly on the trails and the adrenaline rush of besting your buddy or an official opponent in a half-mile drag race.
Best of all, rarely do quads have the prestige of once outperforming the Yamaha YFZ450R in a national MX competition – only the Suzuki QuadSport 400 replica does.
Models
There were only four models produced under this series from 2003 to 2006 before the KFX 400 retired. The debut version of the 4×4 originally came out of the Suzuki DRZ400 dirt bike and was equipped with a smaller carb, toned down cam, and different CDI with a milder curve and lower rev limit. While this setup gave riders extremely usable power delivery, it did not quite tap into the quad’s full potential.
In 2005, Kawasaki made cam and carburetor updates to the four-wheeler that resulted in a night-and-day difference in its overall power. These changes strengthened the KFX 400’s foothold in the ATV landscape as a high-performance machine for dirt roads, trails, and sandbanks.
Kawasaki KFX 400 Specs & Features
Engine
This 400-class machine is brought to life by a 36-mm Mikuni carburetor, later changed to a 37-mm CV-style carb with TPS designed to increase throttle responsiveness.
This carb upgrade was paired with higher lift intake and exhaust cams for the 2005 Kawasaki KFX 400, allowing the DOHC engine to breathe deeper and improving its mid-to-top-end power.
| Engine Type | 4-Stroke DOHC |
| Cylinder Arrangement | Single cylinder |
| Carburetion System | Carburetor, Mikuni BSR36 SS x 1 |
| Engine Cooling | Liquid cooling |
| Bore x Stroke Ratio | 90 x 62.6 mm (3.543 x 2.465 in) |
| Compression Ratio | 11.3:1 |
| Starting System | Electric |
| Displacement | 398 cm³ / 24.3 in³ |
| Maximum Power | 28-32 hp/28.4-32.4 PS (20.9-23.9 kW, estimated) |
| Top Speed | 65-85 mph (104.6-136.8 km/h) – owners’ claim |
| Air Filtration | Polyurethane foam element |
| Lubrication | Dry sump |
| Engine Oil & Quantity | 2.1 US quarts w/ filter 2.2 US quarts w/out filter 2.3 US quarts at disassembly SAE 10W-40 w/ API grade of SJ meeting JASO T903 MA Other options: SAE 5W-30, 10W-30, 10W-50, 15W-40, 15W-50, 20W-50 |
Maintenance: Unlike other sport ATVs, it is not advisable to use a wire to clean the jets or passageways on this quad, as Kawasaki KFX 400 parts may become damaged in the process. Instead, use a dip-type cleaning solution with a spray-type cleaner to ensure all components are clog-free.
Since it is not fuel-injected, you would need to adjust jetting every 3,300-feet increase in altitude to guarantee top performance.
Drivetrain
Thanks to its chain-drive system and vibration-reducing counterbalancer, the KFX400 has the perfect balance of power, handling, and suspension.
If it were to have one minor flaw, it would be acceleration. Stock gearing lends to the vehicle’s top-end speed but does not give it the fastest 0-60-second rating.
Other than that, the machine is a joy to ride. You can start it in any gear with the clutch pulled in. The choke is easily visible on the left side of the handlebars.
| Clutch | Wet, multi-plate type |
| Transmission Type | 5-forward and 1-reverse |
| Gearshift Pattern | 1 down 4 up, foot-operated (forward); foot/hand operated (reverse) |
| Drive System | Chain drive, RK 520KZO 96 links |
| Primary Ratio | 2.960 (74/25) |
| Final Drive Ratio | 2.857 (40/14) |
| Transmission Gear Ratio | Low – 2.538 (33/13) 2nd – 1.666 (30/18) 3rd – 1.238 (26/21) 4th – 1.000 (23/23) Top – 0.846 (22/26) Reverse – 2.153 (28/13) |
Ignition
The ignition switch is on the central pod, and the fuses and battery are safely located under the seat. If you need to swap out stock batteries, a Yuasa YUAM329BS YTX9-BS Battery (view on Amazon) or any other lithium, AGM, or gel variant would be a great replacement.
Just make sure to avoid overcharging as it produces hydrogen that can cause fire when it comes in contact with a spark or short circuit. Also, never replace your stock maintenance-free battery with a conventional one.
| Ignition | Electronic CDI (Capacitor Discharge Ignition) |
| Ignition Timing | 10° BTDC @ 1,500 RPM |
| Spark Plug, Gap | NGK CR7E, DENSO U22ESR-N, gap (0.7-0.8 mm, 0.028-0.031 in) |
| Alternator Type | Triple-phase A.C. generator |
| Rated Output | 65V (AC) @ 5,000 RPM (no-load voltage) |
| Fuse | 20 Amp |
| Battery | 12V, 28.8 kC (8 Ah)/10 Hr, YTX9-BS formats |
| Battery Dimensions (L x W x H) | 150 x 87 x 105 mm (6 x 3.44 x 4.19 in) |
Tires & Brakes
The 4×4’s wheel-and-tire combo makes for an excellent braking system. Stopping power is progressive and does not require death-clutching the brake levers to work. Also, the added grip of factory-installed rubber help with keeping the four-wheeler firmly planted on the tracks.
Stock tires are great on usual off-road terrain, But you may want to change to ITP Holeshot XC Sport ATV Tires (view on Amazon) if you are into desert riding and racing.
| Front Tire, off-road/road air pressure | Tubeless Dunlop AT22 x 7-10, 27.58 kPa (0.28 kgf/cm2, 4 psi) |
| Rear Tire, off-road/road air pressure | Tubeless Dunlop AT20 x 10-9, 34.57 kPa (0.35 kgf/cm2, 5 psi) |
| Front Brake Type | Dual hydraulic discs w/ twin piston calipers |
| Rear Brake Type | Disc brake |
Suspension
The KFX 400 handles high-speed acceleration and bump absorption with ease without transferring hits to the handlebars. Turning is quick and precise, and ripping through wooded trails is effortless. However, more aggressive riding and dry, hard packs expose the vehicle’s weakness and body roll tendency.
| Frame Type | High-tensile tubular steel alloy |
| Caster, Trail | 8.5°, 36 mm (1.42 in) |
| Steering Angle | 41° |
| Turning Radius | 3.1 m (10.2 ft) |
| Front Suspension Type, Travel | Independent, double-wishbone, coil spring, oil damped (adjustable fork preload), 215 mm (8.5 in) |
| Rear Suspension Type, Travel | Aluminum swingarm-type, coil spring, oil damped (preload, rebound and compression damping adjustable), 230 mm (9.1 in) |
Still, the strengths of the suspension system (piggyback shocks and frame strengthening for later-year versions included) outweigh its drawbacks. Bottoming the machine is not an easy task, even after jumping it multiple times – making this machine one of the best in the market.
Dimensions
From its inception, the KFX 400 has been the lightest vehicle in the 400-cc category. To continue as such, it had to offset its suspension upgrades and stronger sub-frame with a new magnesium cover for the valve, clutch, and ignition, aluminum front bumper, and rear grab bar, and aluminum shift lever.
| Length | 1,830 mm (72 in) |
| Width | 1,165 mm (45.9 in) |
| Height | 1,160 mm (45.7 in) |
| Seat Height (Unloaded) | 810 mm (31.9 in) |
| Ground Clearance | 265 mm (10.4 in) |
| Wheelbase | 1,245 mm (49 in) |
| Track (F/R) | 935 mm (36.8 in) / 910 mm (35.8 in) |
| Dry Weight | 169 Kg (373 lbs) |
| Vehicle Load Capacity Limit | 110 Kg (243 lbs) |
Exterior
For a sport quad, the machine surprisingly lacked instrumentation. It came standard with 12V 3W neutral, reverse, and coolant temp warning lights but did not have an analog speedometer/odometer.
Footpegs atop serrated footrests provide the needed support for long trail rides. Plus, the seating position on the quad accommodates both average-height and taller riders.
Dual 30-watt headlights, a 21-watt brake light, and a 5-watt taillight provide the quad superior light distribution.
Body panel color options – Lime Green, Metallic Marble Red, Blazing Orange – add a dash of flair to the machine’s racy aesthetics.
Kawasaki KFX 400 Pricing
The below table shows the list price of all Kawasaki KSF400 models released from 2003 to 2006:
(Source: Nada Guides and Kelley Blue Book)
| Year – Trim – Model Number | List Price | Retail/Trade-In Values |
|---|---|---|
| 2003 Kawasaki KFX 400 KSF400A1 | $5,699 | $1,625 – $2,560 |
| 2004 Kawasaki KFX 400 KSF400A2 | $5,699 | $1,755 – $2,890 |
| 2005 Kawasaki KFX 400 KSF400A3 | $5,699 | $1,890 – $3,110 |
| 2006 Kawasaki KFX 400 KSF400A6F | $5,699 | $2,025 – $3,305 |
Almost similar to retail pricing, auction listings range from $530 to $3,025, with resale units online consisting of ’03 and ’04 KFX models. This makes perfect sense since pre-2005 versions had premature frame issues.
On Craigslist, the range is slightly higher – the most expensive secondhand unit costing $4,000. Buyers may find it a bit of an upset that there is little to no information on trader websites about the mileage/hours, working condition, or any pre-existing problems the quad may have.
You would be in luck if you come across a pre-loved thumper with a full rundown of specs and completed mods in near-mint condition.
The Underrated Racer
Not too many riders know (or remember) the Kawasaki-Suzuki Alliance. This brief coming-together of two automotive giants led to the creation of Suzuki’s LT-Z400 QuadSport and Team Green’s KFX 400.
While enthusiasts recall Doug Gust riding the 400-class QuadSport and winning the national motocross championship in 2004, few realize that the Kawasaki KFX 400 is a replica of that race-winning four-wheeler. The fact that the KFX is built like the official MX champ but is unrecognized for its race-worthy qualities makes it pretty underestimated.
Magazine and consumer reviews on the KFX400 share the same sentiment. Several owners admit to initially thinking very little of the machine, only to realize that the stout quad delivers a lot of power and performs better than the Honda TRX 400EX.
Of course, this may not always be true given that most KFX 400s around are secondhand, with their working conditions largely reliant on the previous owner’s upkeep and care of the quad.
But for a well-maintained unit, one would only need a jet kit, new battery and air filter, wheel spacers, taller (and wider) tires, a smaller tooth wheel to make it perfect for deep mud or rocky terrain.
Kawasaki KFX 400 Pros and Cons
Aficionados would agree that the Kawasaki KFX 400 is as close to a perfect trail machine as you can get. Naturally, it would have its fair share of areas for improvement.
Still, it is unquestionably one of the best hybrid sport quads Team Green has ever released in the market. Let’s take a closer look at the lowlights and highlights of this iconic four-wheeler:
Pros:
- The Kawasaki KFX 400 is not the top gun in its niche, sandwiched between the sport and high-performance categories.
- Despite quick and precise turning, the 4×4 is a bit tippy when pushed too hard in the woods or any terrain with a given level of difficulty.
- Brakes are excellent but still do not make the quad as good as its 450-class counterparts.
- It is one sturdy vehicle but not impervious to bottoming hard, especially if coming up short on a triple or taking on a 65-foot tabletop.
Cons:
- The KFX 400 is a tried-and-tested trail-track combo machine geared toward the aggro rider who occasionally tests the quad’s top-end power on MX/dirt tracks.
- Stock shocks are nearly as refined as aftermarket suspension, making for a smoother ride upfront.
- Its dry-sump lubrication design shortens overall engine height and lends to the quad’s enhanced stability and higher ground clearance.
- The power delivery of the vehicle became more potent with post-2004 enhancements, improving the KFX400’s already-exceptional torque curve
- Lifting the front wheels to overcome obstacles is convenient and trouble-free – thanks to its snappy power and shorter wheelbase.
- Its fast-revving DOHC engine makes traversing wide open spaces in a short amount of time not only fun but also possible.
- With the right kind of modifications, the KFX400 can win you national championships as well as bragging rights when racing with your peers.
About Kawasaki
Founded in 1878, Kawasaki Heavy Industries, Ltd. evolved from being a part supplier for shipping businesses to becoming a prominent institution in the ATV landscape.
The maker of Kawasaki KFX400 is also known for producing industry-leading motorsport vehicles and for its massive production of transit, hydraulic machinery, motorcycles, off-road vehicles, side x sides, personal watercraft, and aerospace and energy systems.
Conclusion – Kawasaki 400 KFX Review
All in all, the Kawasaki KFX 400 delivers in excitement and performance – thanks to its powerful engine, race-type chassis, triple-disc brakes, and manual transmission.
Even today, the dependability and mod-friendly nature of the four-wheeler is more than sufficient to support various sport-riding conditions.
It may not be the cream of the crop in its niche, being a hybrid machine. But it can surely butt heads with the best of thoroughbred racer quads. With its notable strengths, this unsung off-road hero is one of the most fun and praise-worthy machines of all time.
Kris is an avid off-roader and outdoor enthusiast who loves to brave the elements and take on challenging terrain. He also enjoys sharing his passion and knowledge with others so that they, too, can appreciate the ride.
About Kris