Engine
YZ450F-based, "reversed" liquid-cooled, 450 cc, DOHC, 4-valve (titanium), 4-stroke, single with fuel injection & electric starting.
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engine has been tuned for excellent rideability & control
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broad, easy-to-use powerband
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power characteristics optimized for enduro style racing or riding
Rearward-slanted, reversed cylinder design.
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rearward slant moves a significant amount of rotating weight toward the centre of the chassis
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rearward-slanted design centralizes mass for excellent handling & a light feel
"Reversed" engine design - FI system is front-mounted, exhaust exits from rear of cylinder.
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FI throttle body & air box are front-mounted, providing a straight intake path
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straight intake path into the cylinder provides optimum fuel/ air flow for excellent power
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front-mounted intake keeps fuel cooler since engine heat has less effect on incoming fuel (cooler fuel is more dense & increases power)
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design centralizes mass for light, agile handling
Electric start with auto decompression system.
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unit can be re-started in any gear
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elimination of kick starter reduces weight
There is no main ignition switch on this model.
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electric start button (RHS handlebar) activates the entire electrical system
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kill switch (LHS handlebar) if held for a few seconds shuts down entire electrical system
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design reduces weight
Compact 4-valve cylinder head features a 12.8:1 compression ratio.
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titanium 37 mm intake valves & titanium 30.5 mm exhaust valves - TBD
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4-valve design offers optimum flow for excellent power & torque
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compact combustion chamber design
Lightweight titanium valves use load-reduced valve springs.
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titanium valves reduce reciprocating weight & allow for a higher rpm limit (40% lighter than steel valves)
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reduced friction (load reduced valve springs)
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faster-revving & smoother power delivery
Automatic cam chain tensioner.
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reduces maintenance & mechanical engine noise
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special cam chain "sliders" reduce internal frictional losses.
Lightweight hollow intake & exhaust camshafts.
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provide a broad power band well suited to enduro racing or serious recreational riding
Lightweight, ceramic composite coated aluminum cylinder.
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reduced weight (no sleeve or heavy liner) plating is sprayed directly on the aluminum block
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ceramic coating ensures faster, more uniform heat dissipation
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coating enhances the thin film of oil between the cylinder & piston, reducing friction & increasing power
Special cylinder "cutaways" allow air "trapped" under the piston to enter a side chamber (or cutaway).
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reduces horsepower-robbing "pumping losses"
Crankcase also utilizes cutaways which match the cutaways in the cylinder for maximum efficiency.
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reduces horsepower-robbing "pumping losses"
Lightweight, short-skirt, forged aluminum piston.
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lightweight design means faster throttle response
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reduced mechanical vibration for excellent durability
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special coating on piston skirt reduces friction
Piston oil cooler jet nozzle directs oil to the desired portion of the cylinder, rod & underside of piston.
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reduces piston, cylinder & rod temperatures for excellent durability
YZ450F crankshaft & connecting rod feature a carburizing process for excellent durability.
Lightweight, gear-driven counterbalancer shaft.
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reduces vibration for improved rider comfort & reduces rider fatigue
5-speed, wide ratio transmission utilizes a 2-bar, floating shift guide system & a 14 mm shift shaft.
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smooth, positive shifts
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good durability in the event of a crash (14 mm shift shaft)
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optimized ratios for good performance in difficult sections & solid top end speed for fast sections
Heavy duty, multi-plate, clutch with quick access magnesium outer cover.
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clutch is designed for the rigours of enduro riding
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clutch action is light to reduce hand fatigue during extended races / rides
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quick access outer cover provides fast & easy clutch access
44mm Keihin throttle body fuel injection system.
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12-hole injector
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maximizes fuel atomization for more complete combustion & excellent power delivery
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FI settings are specific to enduro racing / riding
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FI benefits include automatic adjustments to insure the optimum fuel - air ratio regardless of outside air temperature & altitude
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other benefits include excellent starting & excellent throttle response
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cold start knob also doubles as an idle adjuster
Optional, compact, hand held "GYTR Power Tuner" allows tailoring of both fuel injection duration & ignition mapping.
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9- different setting points can be accessed for both fuel duration & ignition maps
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maps can be stored & shared with other Power Tuners if desired
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easy access GYTR Power Tuner connector port
NOTE: Competition Only Kit ECU is required for Power Tuner use on the WR450F
Forward mounted air box features a washable, dual-stage, foam air filter.
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No tools required to access air filter
Wet sump lubrication system.
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reduces weight (no remote oil tank or oil lines)
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eases maintenance (easier & faster oil changes)
Easy access "cartridge-type" oil filter for fast, easy oil changes.
Lightweight, single-core, dual radiators with electric cooling fan.
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standard cooling fan maintains consistent engine temperatures during slow speed, technical riding
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radiator fin pitch is optimized for good air flow even at slow speeds
Maintenance-free transistor controlled ignition (TCI).
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produces a strong spark for fast starts
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provides precise ignition timing / mapping for optimum engine performance at all rpms
High capacity AC magneto to power the FI system.
Lightweight, wrap-around exhaust system based on YZ450F design.
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exits from the rear of the engine & circles cylinder body
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design ensures the optimum tuned header length
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maximizes exhaust "pulse effect" for excellent power delivery
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centralizes mass by moving weight closer to the centre of the chassis
Lightweight aluminum / stainless steel muffler (aka silencer).
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multi-expansion design
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spark arrestor equipped