CAUSEWAY YAMAHA

  

        

AN INJECTION OF HYPERACTIVITY

The YFZ450R successfully steps up to the No 1 Sports ATV position by moulding totally uncompromising engineering into instant race-winning potential.

The YFZ450R story starts with a new, massively rigid but very lightweight cast aluminium and steel hybrid chassis. Though the suspension is wider and longer than the YFZ450’s, the YFZ450R is physically shorter overall than its predecessor, giving it a more agile, nimble feel.

Sitting low in this chassis is a 449cc 5-valve DOHC liquid-cooled engine with reshaped intake ports and fuel injection controlled by a 32-bit ECU. The engine’s dry-sump design allows for a shallower crankcase, lowering the centre of gravity still further for even sharper handling. Pressure lubrication from a separate (small) dry-sump tank inside the crankcase reduces weight and rules out oil starvation under high G-forces.

The intake port design and valve timing have both been modified for increased low and midrange power. A new exhaust boosts low and midrange power, while a new five-speed gearbox with taller ratios drives through an up-rated clutch. The result is an ATV packing linear, muscular acceleration.

Increased wheel travel and longer suspension arms maximise the YFZ450R’s performance potential without compromising overall balance, handling or agility. New tread-pattern tyres make turn-in even sharper and a lightweight 220mm ‘wave’ disc reduces unsprung weight. Ideal riding ergonomics are made possible by a four-setting handlebar adjustment system, a new throttle lever, remodelled seat and wider footrests.

Key Features:

♦   The fuel-injected 449cc engine uses the cylinder head and cylinder from the YFZ450 for superb power characteristics.
♦   A newly designed crankshaft handles the increased torque, as well as the counter balancer that has an increased ratio for superior vibration control.
♦   Camshafts are all new for this model, and are designed to maximise available torque in the low and mid ranges.
♦   Fuel injection uses a 12-hole injector that provides exceptional atomisation of the fuel for maximum combustion efficiency and power delivery.
♦   New dual rate springs – improved grip and absorption in compression and expansion stroke.
♦   New 3-way adjustable dampers – compression, rebound, high speed compression.
♦   Large diameter hydraulic flow dampers means greater stroke feeling and bump absorption.
♦   Strong, lightweight cast aluminium and steel chassis.
♦   Wider, longer suspension.
♦   High power, delivered smoothly from the new fuel-injected five-valve engine.
♦   Dry-sump design for lower weight and reliable lubrication under high G-forces.
♦   New cylinder head, valve timing and exhaust boost low and midrange power.
♦   Taller ratio gearbox with uprated clutch.
♦   Improved rider-centric ergonomics for optimal comfort and operation.
♦   Out of the box’ competitiveness.

SPECIFICATIONS
ENGINE/IGNITION/TRANSMISSION
Type	Single cylinder, liquid-cooled, 4-stroke, DOHC, 5-valve
Displacement - (cc)	449
Bore Stroke - (mm)	95.0 x 63.4
Compression	11.6:1
Lubrication	Dry Sump
Fuel Management	Mikuni 42mm EHS
Ignition	TCI
Starter	Electric
Fueltank - (L)	10
Transmission	5-speed, manual clutch
Final Transmission	Chain
CHASSIS
Length - (mm)	1795
Width - (mm)	1240
Height - (mm)	1065
Seat Height - (mm)	810
Wheelbase - (mm)	1270
Clearance - (mm)	115
Wet Weight - (kg)	184
FRONT END
Suspension Front	Independent double wishbone
Tyres Front	AT21 x 7-10 radial
Brakes Front	Dual hydraulic disc, twin piston
REAR END
Suspension Rear	Swing arm
Tyres Rear	AT20 x 10-9 radial
Brakes Rear	Hydraulic wave type disc, twin piston