- The design goals for the YZ450F are a balance of easy cornering, a lightweight & compact feeling due to excellent mass centralization and a deep, useable power band.
- "Reversed" liquid-cooled, 450cc, DOHC, 4-valve (titanium), 4-stroke, single with fuel injection. The engine has been tuned for excellent "ride-ability and controllability" and delivers a broad power band with "deeper power" in the higher rpm range.
- Unique engine design features a rearward slanting cylinder that is "reversed" compared to traditional designs. The FI throttle body and air box are front mounted and provide a straight intake path, while the exhaust exits from the rear of the cylinder. This design is used to centralize mass for excellent handling and a light feeling. It also means that engine heat will have less "heating effect" on the incoming fuel charge (cooler fuel helps increase power). The other major benefit is the straight shot intake system which maximizes power output. The engine is slanted 7.5 degrees rearward.
- Compact, 4-valve cylinder head design, features a 12.5:1 compression ratio. The intake valves are 37mm in diameter while the exhaust valves are 30.5 mm, for optimum flow and improved power.
- Lightweight titanium valves (intake & exhaust) and load-reduced oval valve springs reduce reciprocating mass for less friction, faster-revving and a smoother-hitting power delivery across the rev range.
- Automatic cam chain tensioner reduces maintenance while special cam chain "sliders" reduce internal frictional losses.
- High performance, light weight hollow intake and exhaust camshafts.
- The lightweight aluminum cylinder features a ceramic composite coating applied directly to the aluminum, eliminating the need for a liner or sleeve. The ceramic coating insures faster, more uniform heat dissipation, reduced friction and a longer service life.
- The cylinder is "offset" relative to the crankshaft to reduce frictional losses between the piston and the cylinder wall during the power stroke.
- Special cylinder design features cutaways that allow the air "trapped" under the piston to enter a side chamber (or cutaway) to reduce horsepower-robbing "pumping losses."
- The crankcase also utilizes cutaways to reduce "pumping losses". The crankcase cutaways match the cutaways in the cylinder for maximum efficiency.
- Lightweight, short-skirt, forged aluminum piston features a unique crown design that improves combustion efficiency and a special surface treatment on the skirt to reduce friction. Con rod is carburized for excellent durability.
- Piston oil cooler utilizes a pinpoint nozzle that directs oil to the desired portion of the cylinder and underside of the piston, which reduces piston, cylinder and rod temperatures for excellent durability.
- Lightweight gear driven counterbalancer shaft reduces vibration for improved rider comfort and less rider fatigue.
- The crankcase features a tri-axis layout for the crank, main and drive axles. This tri-axis design keeps the crankcase more compact while also centralizing mass for excellent handling.
- Revised 5-speed transmission features a 2-bar shift guide system, a revised shift cam stopper and a 14mm shift shaft. The benefit is smooth, positive shifts and good durability in the event of a crash. Overall, the transmission is well matched to engine output and reduces "driving force" losses.
- Heavy duty multi-plate (wet) clutch
- Quick-access, lightweight magnesium outer clutch cover for fast, easy clutch maintenance.
- Keihin 44mm throttle body fuel injection system is a battery-less design. The 12-hole injector maximizes fuel atomization for more complete combustion and excellent power delivery. The benefits of fuel injection include constant ongoing adjustments to insure the optimum fuel - air ratio regardless of outside air temperature and altitude. Other benefits include improved starting and improved throttle response. There is a cold start knob which also doubles as an idle adjuster too.
- The injector spray pattern, spray direction and the distance to the intake valves have been optimized, while the specially designed straight intake tract helps to maximize the benefits of the FI system and overall power output.
- Revised return spring on throttle body for less fatigue during long motos or extended riding periods.
- New ECU settings for both ignition timing and the FI system settings.
- Optional, compact, hand held "YZ Power Tuner" allows tailoring of both fuel injection settings and ignition mapping. Nine (9) different setting points can be accessed for both the FI map and the ignition map. Maps can be stored and shared with other Power Tuners if desired.
- Forward mounted air box features a flat style, washable, dual-stage, foam air filter which is easily accessible without removing the tank or seat. New quick release, no tools required, fasteners on the air box cover for faster servicing.
- Wet sump lubrication system reduces weight, allows for more compact engine cases and eases maintenance.
- Oil volume in the engine has been optimized (0.95 L) to reduce weight and oil drag related power losses.
- Compact, lightweight in-tank electric fuel pump.
- Maintenance-free transistor-controlled digital ignition (TCI) ensures fast starts and great performance at all rpms.
- High capacity ACM (alternating current magneto) is used to eliminate the need for a battery.
- Automatic decompression system ensures easy starts in any gear.
- The exhaust pipe has an innovative layout, circling the cylinder, giving the exhaust pipe the correct tuned length for an excellent exhaust pulse effect. The exhaust pipe has three different diameters throughout the exhaust tract, bringing out excellent power characteristics. This design centralizes mass by moving weight closer to the centre line of the bike.
- Re-packable lightweight aluminum / stainless steel muffler (aka silencer) sound output is 94dba to meet the current AMA and CMRC sound regulations.
- Compact, lightweight, single core, dual radiators provide outstanding cooling efficiency.
- Special "G" sensor system will shut down the fuel injection system if the bike lies on its side for more than 10 seconds to help prevent costly engine damage. There is 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.
- Easy access oil filter.
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- Compact "Bilateral Beam" aluminum frame centralizes mass for exceptional handling and a lightweight feeling. The frame is made up of forged, cast and extruded aluminum parts providing outstanding strength, an optimum rigidity balance and shock absorbing qualities that contribute to exceptional cornering. This frame is compact and offers excellent "rider - machine communication" (a.k.a. feedback). The engineers have optimized the balance between strength, rigidity and flex. The key goal of the chassis is faster and easier cornering ... one of the main keys to winning races.
- Revised front engine mounts
- Lightweight, tapered aluminum swingarm is produced using "hydro forming", a special method that uses high pressure liquid to form shapes. The swingarm pivot shaft is 17mm.
- Lightweight detachable rear sub frame is constructed of square-section, lightweight aluminum pipe with no bends. The detachable design allows easy access when servicing rear suspension components.
- Cast aluminum upper triple clamp. The handle bar clamps are rubber mounted for improved rider comfort.
- Adjustable handlebar clamps offer a total of 4 different handlebar positions with an adjustment range of 30mm, to suit a wide variety of riders.
- Revised 48mm, adjustable, inverted, Kayaba cartridge fork offers 310mm (12.2") of wheel travel. Inner tubes feature a special surface treatment for smoother performance. Optimized fork settings with slightly stiffer spring rate. Front fork adjustments include: 20-way compression damping and 20-way rebound damping. Optional fork springs are available through Genuine Yamaha parts.
- The fork features a twin-chamber, "Speed Sensitive System" design meaning the damper unit is in a separate structure which prevents aerated fork oil from entering the inner damper assembly and reducing its damping abilities. Since the inner damper is pressurized, it also eliminates bubbles forming in the oil.
- The 48mm inverted KYB fork also features a Transfer Control Valve (TCV). The TCV enhances the damping force from mid to full stroke and improves bottoming characteristics. The benefit of TCV is more precise control throughout the full suspension stroke. The TCV is located on the upside of the spring and 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. The "self-supporting" design reduces friction for smoother fork operation.
- Monocross link rear suspension system features a fully adjustable, large capacity, Kayaba piggyback shock which provides 315mm (12.4") of wheel travel and features separate adjusters for high- and low-speed compression damping. The shock is in-line with the center axis of the bike for excellent control. Shock adjustments include: spring preload, 30-way rebound damping, 20-way low-speed compression damping and 2 turns of high speed compression damping.
- 250mm floating front "wave-style" disc reduces weight, improves cooling and adds style too. The disc is squeezed by a compact Nissin twin piston caliper fitted with lightweight aluminum pistons.
- "Shorty style" adjustable front brake lever can be adjusted to fit various hand sizes.
- 245mm rear disc brake features a "wave-style" disc. The rear disc is squeezed by a single piston compact Nissin caliper.
- Lightweight, compact, integrated Nissin rear master cylinder (fluid reservoir is integrated into the top of the master cylinder) provides strong stopping power with excellent feel and control.
- The rear caliper and the lower portion of the wave disc are protected by heavy duty plastic protectors.
- Plastic resin 7.5 litre fuel tank is located under the seat, reducing the centre of gravity and centralizing mass for exceptional handling performance. The fuel tank is able to pivot backwards 180 degrees (flip onto its back) without disconnecting the fuel line for easier servicing under the tank.
- Compact body work reduces weight and enhances the lightweight feel and look of the YZ450F. This "minimal design" bodywork allows for fast, easy rider movements. The minimal design aids in keeping the body looking good throughout the life of the machine.
- Graphics are impregnated directly into the plastic rad shrouds. They will not peel off or get damaged by pressure washing.
- Flat design seat for easy rider movements and features a "cap cover" to access the fuel cap. There is no fuel cap visible with this design. The fuel filler "cap cover" snaps into place, via grommets. The non-slip seat cover material resists clogging with dirt or mud to ensure long lasting good looks.
- Rugged, 21" front and 19" rear black Excel rims provide exceptional durability and help reduce unsprung weight for optimal suspension performance and handling.
- New Dunlop MX52 tires mounted to new black rims
- 22mm front axle increases overall front end rigidity.
- 25mm rear axle and a hub design which features a second bearing on the sprocket side for increased rigidity and durability.
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"Reversed" liquid-cooled, 450cc, DOHC, 4-valve (titanium), 4-stroke, single with fuel injection. The engine has been tuned for excellent "ride-ability and controllability" and delivers a broad power band with "deeper power" in the higher rpm range.
Innovative circular exhaust system provides the correct tuned length for an excellent exhaust pulse effect. The exhaust pipe has three different diameters throughout the exhaust tract, bringing out excellent power characteristics.
Compact "Bilateral Beam" aluminum frame centralizes mass for exceptional handling and a light, easy to handle feeling.
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