The KFX450R ATV uses a powerplant based on Kawasaki’s highly
acclaimed KX™450F motocross engine. With the addition of an efficient and
highly-responsive 32-bit digital fuel injection system, the KFX450R’s engine
produces more torque in the low and medium rpm ranges for outstanding hole-shot
acceleration. The use of fuel injection helps ensure that the engine’s
performance remains consistent and is virtually unaffected by changes in
temperature or altitude. This ATV’s ability to find traction is superb,
and its four-stroke torque helps keep the wheels hooked-up for improved handling
and higher corner speeds. Other race-ready features include a lightweight
titanium exhaust header pipe and a durable forged piston.
First Ride Review:
The KFX450R starts with ease. It is a bit strange to hear
a electronic fuel injection pump working when you turn the key on. I feel
like I am in my sand rail. There is no choke, but there is a idle adjusting knob
that is pulled for cold starting.
The parking brake is super easy to use, and actually
works. Just flip the lever on or off. When the brake is on, the
clutch will not depress. Nice safety feature.
Reverse gear selection is a breeze. Clutch in. Select 1st
gear. Push the reverse lockout lever, then push the gear selector down one
more click. Red light comes on and you are in reverse. When you are
done, click the gear selector up to 1st again. Simple.
The front of the chassis is taken directly from race proven
aftermarket systems and is actually similar in design to the popular 250R Roll
Design narrow front end.
The seat is pretty hard. Going to have to fix that.
Power-wise, the KFX450R in stock form felt about the same as
other 450 ATVs with maybe a slight edge to the KFX450R. The power is very linear
and controllable. It will be interesting
to see how it reacts after being uncorked and remapped.
** Photos courtesy of Mike's Cycle in Placerville, CA
Features
449cc Liquid-cooled, four-stroke single, DOHC, four
valves per cylinder
Based on the engine from the World Championship winning KX™450F
A lightweight forged piston reduces reciprocating weight.
Triple piston rings and a 21mm diameter piston pin help increase
durability and reduce necessary maintenance.
The intake ports feature a special coating. The extremely smooth
surfaces improve intake efficiency at all rpm.
Lightweight titanium valves and aluminum valve spring retainers reduce
reciprocating weight and boost high-rpm reliability.
Lightweight high-performance titanium exhaust header contributes to low
and mid-range throttle response.
Electric starting facilitates quicker stall recovery and lowers rider
fatigue.
Large-volume airbox contributes to both intake efficiency and the sharp
engine response. An air duct fashioned from polyethylene (known for its
ability to resist deformation caused by intake pulses) helps ensure stable
engine performance.
Torque delivery is tuned to match the rear tires’ ability to deliver
traction, making it easier to accelerate without excessive wheelspin.
Efforts were made to achieve the widest possible torque curve, so that traction
can be maximized through a greater part of the rev range.
Asymmetrical high-acceleration cams yield high intake efficiency.
The compression ratio in the KFX450R is 12:1.
The engine requires a minimum of 91 octane fuel.
The engine puts out 43 HP and 31.1 foot pounds of torque.
Digital Fuel Injection
32-bit digital fuel injection system uses a 42mm throttle body.
This system measures coolant temperature, air intake temperature, air intake
pressure, engine speed and throttle position, then automatically delivers the
ideal amount of fuel to optimize power delivery.
Crisp engine response is especially advantageous for instant
acceleration after landing jumps.
Fuel injection also provides trouble-free starting – a great benefit
in races where riders line up with their engines off and need to start their
engines before being able to blast away from the starting line.
Fuel injection allows the use of a lighter throttle return spring. This
helps reduce rider fatigue, because less pressure is required at the throttle
lever.
Transmission
The five-speed (one-down, four-up) manual transmission locates the
reverse gear below first. Actuating the reverse-lock release lever when in first
gear allows you to shift “down” into reverse.
Compact reverse-lock release lever can be activated with the right
thumb, allowing the reverse gear to be engaged while still keeping the front
brake lever depressed.
The combined weight of the reverse gear system and the lightweight
aluminum chassis is no heavier than using a steel frame without reverse.
Aluminum Chassis
Highly rigid aluminum frame contributes to the KFX’s
excellent handling and traction. The frame’s high torsional rigidity
enhances stability in corners and allows the suspension to be easily set up to
suit course conditions.
Designed for high corner speeds, the KFX ATV sits low to the ground,
helping to reduce roll tendencies.
Mounting the battery and coolant tank in front of the engine lowers the
center of gravity, and helps weight the front wheels for increased traction when
cornering.
Single box-tube lower frame contains the front A-arm attachment points.
This design is narrower than the competition’s frames and enables the use of
longer lower A-arms.
The aluminum frame weighs in a 26 lbs.
Advanced Suspension Design
Positive and negative suspension travel enhances the front wheels’
ability to stay in constant contact with the ground. This helps maintain
traction and steering authority during hard acceleration and in situations where
the ground drops away.
Dual-rate front springs help deliver progressive suspension travel to
provide excellent rough-surface handling.
Extra-long lower front A-arms help minimize camber variations through
the suspension stroke, to maximize front wheel traction and boost stability.
Motocross style rear shock features both high and low-speed compression
adjustability as well as adjustable rebound damping.
Cast aluminum rear swingarm features curved lines and rounded edges to
help disperse stress, as well as different wall thickness for each surface,
resulting in a design that is both light and strong.
The swingarm’s high torsional rigidity contributes to excellent rear
wheel traction
The rear axle is tapered for reduced unsprung weight.
Front and Rear Disc Brakes
Dual front hydraulic disc brakes offer consistently strong
stopping performance
Petal-type rear brake rotor reduces unsprung weight and helps clean the
brake pads for more efficient braking performance in difficult conditions.
Integrated rear parking brake is designed to be easily engaged and
released while wearing gloves. When engaged, the parking brake lever also
prevents the clutch lever from being actuated.
Additional Features
Two-tone seat features a smooth top surface for excellent rider mobility
and slip-resistant sides for good grip when hanging off in corners.
Seat, tank and side covers are shaped to allow excellent rider mobility
and to provide support when hanging off in corners.
Tapered Renthal Fatbar offers both strength and light weight.
Handlebar mount designed to accommodate other MX-type handlebars,
enabling riders to select from numerous after-market styles.
Specially designed rear wheels feature reinforcing plates for the rims.
Located on the axle side of the rims, these plates reinforce the rims where
strength is most needed while minimizing weight.
Wide front bumper, can be gripped with two hands to push/pull the ATV
Two-piece “lapped” front and rear fenders can be replaced separately
in the event they are damaged.
Detachable front headlight assembly can easily be removed to reduce
weight when racing.
Optional kick-start system is available for MX-style (GNC) races where
light weight is a priority.
