ENGINE
Potent, liquid-cooled, 250cc, DOHC, 4-valve power plant with super light titanium intake valves & electronic fuel injection. This engine out performs its 250cc displacement and offers best in class performance.
Electric starting & automatic decompression system.
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easy no hassle starting
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decompression system reduces battery power requirements... reducing weight
Lightweight magnesium cylinder head cover reduces weight.
Double overhead cam, 4-valve, compact combustion chamber.
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features a compact "pent-roof" combustion chamber design for optimum combustion
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maximum breathing efficiency for excellent power output
Lightweight titanium intake valves & load-reduced oval valve springs.
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titanium valves reduces reciprocating weight & allows 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
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"Ti" intake valves are 30mm in diameter, steel exhaust valves are 24.5mm
Valve adjustment intervals are every 42,000 kms.
High performance intake & exhaust camshafts
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provide outstanding class leading power
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cams feature a WPC (Wonder Process Craft) treatment that increases surface hardness for excellent durability & reduced sliding resistance
Downdraft-type straight design intake port.
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most efficient intake flow for maximum engine performance
Automatic, hydraulic 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 roller bearing style crankshaft.
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optimized mass delivers excellent throttle response & strong acceleration
Engine counter balancer
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reduces vibration for improved rider comfort & reduced rider fatigue
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despite being "only" a 250 this unit can cruise at highway speeds comfortably
Direct ceramic composite plated cylinder uses "liner less" bores.
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ceramic coating sprayed directly on the aluminum block, eliminating the liner & reducing weight
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excellent heat dissipation for consistent power delivery
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coating enhances the thin film of oil between the cylinder & piston, reducing friction & increasing power
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
Piston oil cooler jet nozzle
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directs oil to the desired portion of the cylinder & underside of the piston
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reduces piston, cylinder & rod temperatures for excellent durability
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 special "cutaways"
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reduces horsepower-robbing "pumping losses"
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crankcase cutaways match cylinder cutaways for maximum efficiency
Wet sump lubrication system.
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reduces weight & complexity versus a dry sump system
Easy access element-type oil filter & drain plug for fast oil changes.
38 mm Mikuni throttle body fuel injection system.
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system uses throttle position sensor (TPS)
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12 hole injector with dual spray pattern for optimum fuel atomization
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fuel injection benefits include choke-free starting, steady idling during warm up, excellent fuel economy & reduced emissions
Wide ratio 6-speed transmission with heavy duty clutch
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optimized gear ratios for both on & off road riding
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transmission adopts a "shower type" lubrication system for great reliability
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6th gear is an overdrive gear to reduce engine rpm at highway speeds
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clutch lever pull is light & easy
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Quick-access, lightweight aluminum outer clutch cover
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allows fast, easy access to the clutch
Easy access, 4.1 liter air box with foam air filter
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special intake control valve provides state of the art intake & emission control
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foam air filter is a washable design to reduce tune-up costs
Single, 9.5KW rad... located on right side, below steering head.
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electric cooling fan maintains consistent engine temperatures even in stop & go traffic or during technical off road riding
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 performance direct ignition coil (ignition coil is built into the spark plug cap).
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reduces weight & complexity
Lightweight, compact "rare-earth-type" ACM (alternating current magneto).
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reduced weight
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14V & 350W output
Upswept exhaust system
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stainless steel header pipe & a compact 3-stage expansion type muffler
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honeycomb catalyzer reduces exhaust emissions
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system maximizes engine power & allows hassle-free replacement of the oil filter element
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cleanable screen-type spark arrestor
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heat shields protect rider & passenger
Exhaust system also features Yamaha's EXUP System (Exhaust Ultimate Power Valve).
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single butterfly valve prevents the "blow back" phenomenon caused by "valve overlap"
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EXUP system eliminates "flat spots" in the power band & reduces emissions too.
Solenoid activated Air Induction System (AIS) reduces harmful exhaust emissions.
Heavy duty plastic water pump & stator cover guards.
