Featuring a "reversed" rear slanted engine design for mass centralization, minimal bodywork and a proven KYB "SSS" suspension system, the YZ450F offers class leading power in a 250 sized chassis. The YZ450F balances the 3 essential elements of an ultimate motocrosser: easy cornering, lightweight & compactness and a deep, useable power band.
Power: The "reversed" liquid-cooled, 450cc, DOHC, 4-valve (titanium), single has been tuned for excellent "ride-ability and controllability" and delivers a broad, deep power band.
Frame, suspension & brakes: The compact "Bilateral Beam" aluminum frame centralizes mass for exceptional handling while the fully adjustable "SSS" KYB suspension soaks up the rough staff with ease. And our large 270 mm front disc brake slows it all down in a hurry.
Key Improvements for 2017
- Revised air filter cover & fasteners
- Revised rear wave-style brake rotor
- New tire tread pattern front & rear
- Revolutionary reversed engine design with front mounted FI system & rear exiting exhaust
- Mass centralizing rearward-slanted-cylinder helps keeps weight centred in the chassis
- Launch Control System
- "Battery-less" 44mm throttle body FI & easy access airbox
- Compact aluminum Bilateral Beam frame & aluminum swingarm
- Industry-leading, fully adjustable KYB® "SSS" fork & Monocross rear suspension
- Large 270 mm front disc brake & twin piston caliper
- GYTR® Power Tuner Ready
- Design goals for the YZ450F are a balance of easy cornering, a lightweight & compact feeling due to excellent mass centralization and a deep power band tuned for excellent "ride-ability & controllability".
- "Reversed" liquid-cooled, 450cc, DOHC, 4-valve (titanium), 4-stroke, single with fuel injection.
- Rearward slanted, reversed cylinder design: rearward slant moves a significant amount of rotating weight toward the centre of the chassis; 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): FI throttle body & air box are front mounted, providing a straight intake path; straight intake path into the cylinder, provides optimum fuel/ air flow for excellent power; front mounted intake keeps fuel cooler since engine heat has less effect on incoming fuel (cooler fuel is more dense & increases power); design centralizes mass for light, agile handling
- Compact 4-valve cylinder head features a 12.5:1 compression ratio: 37 mm titanium intake valves & 30.5 mm titanium exhaust valves; 4-valve design offers optimum flow for excellent power & torque; compact combustion chamber design
- Lightweight, hollow intake & exhaust cams: excellent power & controllability in the low to mid rpm range; strong high rpm power
- Lightweight titanium valves use load-reduced oval valve springs: titanium reduces reciprocating weight & allows for a higher rpm limit (40% lighter than steel valves); reduced friction (load reduced) valve springs
- Automatic cam chain tensioner: reduces maintenance & mechanical engine noise; special cam chain "sliders" reduce internal frictional losses.
- Lightweight, ceramic composite plated aluminum cylinder: reduced weight... no sleeve or heavy liner... plating is sprayed directly on the aluminum block; ceramic coating insures faster, more uniform heat dissipation; coating enhances the thin film of oil between the cylinder & piston, reducing friction & increasing power
- Cylinder is "offset" relative to the crankshaft (to exhaust side): reduces frictional losses between piston & cylinder wall during the power stroke
- Cylinder "cutaways" allow air "trapped" under the piston to enter a side chamber (or cutaway): reduces horsepower-robbing "pumping losses"
- Crankcase also utilizes special "cutaways": reduces horsepower-robbing "pumping losses"; crankcase cutaways match cylinder cutaways for maximum efficiency
- Lightweight, short-skirt, forged aluminum piston: lightweight design means faster throttle response; reduced mechanical vibration for excellent durability; special coating on piston skirt reduces friction
- Piston oil cooler jet nozzle directs oil to the cylinder, rod & underside of piston: reduces piston, cylinder & rod temperatures for excellent durability
- Carburized (type of heat treatment) connecting rod for excellent durability.
- Lightweight gear driven balancer shaft: reduces vibration for improved rider comfort & reduces rider fatigue
- 5-speed transmission utilizes a 2-bar, floating shift guide system & a 14 mm shift shaft: smooth, positive shifts; good durability in the event of a crash (14 mm shift shaft); see spec page for gear ratios
- Heavy duty, multi-plate, clutch with quick access magnesium outer cover: quick access outer cover provides fast & easy clutch access; light lever pull for reduced hand fatigue
- 44mm Keihin throttle body fuel injection system: 12-hole injector; maximizes fuel atomization for more complete combustion & excellent power delivery; FI benefits include automatic adjustments to insure the optimum fuel - air ratio regardless of outside air temperature & altitude; other benefits include excellent starting & excellent throttle response; cold start knob also doubles as an idle adjuster
- The injector spray pattern, spray direction and the distance to the intake valves have been optimized. Forward mounted straight intake tract helps to maximize the benefits of the FI system & overall power output.
- Optional, compact, hand held "GYTR Power Tuner" allows tailoring of both fuel injection duration & ignition mapping: 9- different setting points can be accessed for both fuel duration & ignition maps; maps can be stored & shared with other Power Tuners if desired; easy access GYTR Power Tuner connector port
- Revised forward mounted air box with washable, dual stage foam air filter: No tools required to access air filter; new air box cover & new quick release fastners; washable design reduces maintenance costs
- Wet sump lubrication system: reduces weight (no remote oil tank or oil lines); eases maintenance (easier & faster oil changes); oil volume is optimized to reduce oil related drag & weight
- Easy access "cartridge-type" oil filter.
- Compact, lightweight, single core, dual radiators provide outstanding cooling efficiency.
- Maintenance-free transistor controlled ignition (TCI): produces a strong spark for fast starts; 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: exhaust exits from the rear of the cylinder & circles cylinder body; design ensures the optimum tuned header length; maximizes exhaust "pulse effect" for excellent power delivery; centralizes mass by moving weight closer to the centre of the chassis
- Lightweight, aluminum, re-packable muffler (aka silencer): revised muffler bracket reduces weight; sound output is 94 dB meeting CMRC & AMA regulations
- Launch control system (LCS): provides smoother, quicker starts with less wheel spin & front wheel lift; allows rider to concentrate on clutch control, body position & machine; system functions in 1st & 2nd gears only and is disabled as soon as the bike is shifted into 3rd gear; ECU controls the system and adjusts rpm to limit wheel spin & wheelies; activation button is on the LHS handlebar & features a LED indicator light.
- Special "G" sensor system: shuts down fuel injection system if bike lies on its side for more than 10 seconds; helps prevent costly engine damage; no special procedure to re-start the bike... just kick it and go.
- Works-style race-spec "barrel adjuster" for on-the-fly clutch lever free play adjustments.
- Compact, lightweight "Bilateral Beam" aluminum frame: centralizes mass for exceptional handling & manoeuvrability; frame offers an optimum rigidity balance between strength, rigidity & tuned flex, plus excellent shock absorbing qualities; frame design offers excellent "rider - machine communication" (a.k.a. feedback); key goal of the chassis is fast & easy cornering ... one of the main keys to winning races
- Lightweight, tapered aluminum swingarm: lightweight design reduces unsprung weight for optimum suspension performance; excellent rear wheel traction & control; 25mm rear axle
- Lightweight detachable rear sub frame: constructed of square-section, lightweight aluminum pipe with no bends; allows easy access when servicing rear suspension components; detachable design reduces costs in the event of a loop out
- Adjustable handlebar holders offer a total of 4 different handlebar positions with an adjustment range of 30mm: suits wide variety of rider sizes; handlebar holders are rubber mounted for reduced vibration & improved rider comfort
- 48mm, adjustable, inverted, Kayaba "SSS" cartridge fork with 310mm (12.2") of wheel travel: front fork adjustments include: 20-way compression damping & 20-way rebound damping; inner tubes feature a special friction reducing coating; 22 mm front axle; optional fork springs are available through Genuine Yamaha parts
- Fork features a twin-chamber, "Speed Sensitive System" design: damper unit is in a separate structure (completely separated air & oil chambers); helps prevent aerated fork oil from entering the inner damper assembly & degrading its damping abilities; since the inner damper is pressurized, it also eliminates bubbles forming in the oil.
- Fork also features a Transfer Control Valve (TCV): TCV enhances damping from mid to full stroke & improves bottoming characteristics; TCV offers more precise control throughout the full suspension stroke; TCV is located on the upside of the spring & its function is controlled by piston speed, not piston position, hence the term "Speed Sensitive System fork".
- Large "wrap-around" plastic fork protectors provide excellent lower fork tube protection: "self-supporting" design reduces friction for smoother fork operation
- Monocross link rear suspension with 315 mm (12.4") of wheel travel: features a fully adjustable Kayaba piggyback shock; separate adjusters for high- and low-speed compression damping; shock is in-line with the center axis of the frame for excellent control; shock adjustments include: threaded spring preload, 20 -way low-speed compression damping, 2 turns of high speed compression damping & 30-way rebound damping
- 270mm floating front "wave-style" disc & compact Nissin twin piston caliper: wave disc design reduces weight & improves cooling (wave design offer more surface area for better cooling); excellent braking performance
- "Shorty style" adjustable front brake lever can be adjusted to fit various hand sizes.
- 245 mm rear disc brake features a "wave-style" disc & single piston Nissin caliper & master cylinder: revised rear motor for improved heat resistance
- Rear caliper & lower portion of the wave disc are protected by heavy duty plastic protectors.
- Lightweight, plastic resin 7.5 litre fuel tank: reduces centre of gravity & centralizes mass for exceptional handling & a lightweight feeling; tank can be flipped on its back without disconnecting fuel line (easy servicing under the tank); compact in-tank electric fuel pump
- Compact body work: reduces weight & enhances the lightweight feel and look of the YZ450F; flat design, "minimal" bodywork allows for fast, easy rider movements & a natural riding position; minimal design aids in keeping the body looking good (less plastic to scratch or damage); graphics are impregnated directly into the plastic rad shrouds & will not peel off or get damaged by pressure washing
- Flat seat design: provides easy rider movements; features a "cap cover" to access the fuel cap; non-slip seat cover material resists clogging with dirt or mud
- Rugged Excel rims: excellent durability; reduces unsprung weight for optimal suspension performance & handling; front rim size is 1.60 x 21", rear is 2.15 x 19"; hub features second bearing on sprocket side for increased rigidity & durability
- Extra wide foot pegs provide excellent grip
- Convenient oil level sight glass
- Folding shift lever tip helps prevent damage
- Heavy duty DID 520 chain
- Lightweight Sun Star sprocket
- Heavy duty rubber swingarm protector
- Lightweight chain guide / support helps reduce chance of chain derailment & helps protect rear sprocket
- Clutch cable features integrated silicone grease & Teflon liner for smooth cable operation
- Easy access GYTR Power Tuner & Yamaha Diagnostic tool connectors
- Engine: 4-stroke, liquid-cooled, DOHC, 4-valve (titanium), single
- Displacement: 449 cc
- Bore and Stroke: 97 x 60.8 mm
- Compression Ratio: 12.5:1
- Fuel Delivery: Keihin 44mm throttle body F.I.
- Lubrication: Wet sump
- Ignition / Starting: TCI / Kick
- Transmission: 5-speed transmission; primary ratio 2.609 (60/23); secondary ratio 3.692 (48/13); 1st gear 1.929 (27/14); 2nd gear 1.533 (23/15); 3rd gear 1.300 (26/20); 4th gear 1.091 (24/22); 5th gear 0.952 (20/21)
- Final Drive: Chain
- Suspension (Front): Adj. 48mm, inverted fork / 310mm (12.2 in.) wheel travel
- Suspension (Rear): Fully adj. Monocross / 315mm (12.4 in.) wheel travel
- Brakes (Front): 270 mm, floating disc / twin piston caliper
- Brakes (Rear): 245 mm, disc / single piston caliper
- Tires (Front): 80/100-21
- Tires (Rear): 120/80-19
- Length: 2,180mm (85.8)
- Width: 825mm (32.5 in.)
- Height: 1,280mm (50.4 in.)
- Wheelbase: 1,480mm (58.3 in.)
- Ground Clearance: 330mm (13 in.)
- Seat Height: 965mm (38 in.)
- Fuel Capacity: 7.5 L (1.7 Imp. gal.)
- Wet Weight: 112kg (247 lb.)
- Colour(s): Purplish White, Yamaha Racing Blue
Specifications, appearance, and price of product are subject to change without notice.
Fuel economy estimates are based on US EPA exhaust emission certification data obtained by Yamaha and converted into Canadian measurements. Your actual mileage will vary depending on road condition, how you ride, maintain your vehicle, accessories, cargo and operator/passenger weight.