Yamaha YZ450F - wikipedia Yamaha YZ450F Yamaha YZ450F Manufacturer Yamaha Motor Company Class Motocross Engine DOHC, multivalve, water - cooled, four - stroke, single The Yamaha YZ450F is a four - stroke racing motocross bike built by Yamaha Motor Corporation. It was the successor to the previous YZ426F which was discontinued in 2003. It is credited by Cycle World and Dirt Rider magazines as the bike that started the four - stroke dirt bike revolution. It is a replacement for the YZ250, which is slowly being phased out. The 2006 YZ250F and YZ450F were the first production motorcycles equipped with titanium suspension springs. The WR450F is the enduro version of the YZ450F. Contents 1 Introduction 2 First generation : YZ400F 1998 -- 2000 3 Second generation : YZ426F 2001 -- 2002 4 Third generation YZ450F 2003 -- 2005 5 Fourth generation YZ450F 2006 -- 2009 6 Fifth generation YZ450F 2010 - 2013 7 References 8 External links Introduction For many years, the motocross world almost exclusively used two - stroke engines. AMA racing classes had two classes : 125 cc and 250 cc two - strokes, with no provision for four strokes. Most riders considered four - stroke engine technology to be largely utilitarian and uncompetitive, relegated solely for trail riding. In 1996, the AMA changed racing rules to allow 450 cc four strokes to compete in the same racing class as 250 cc two - strokes. Yamaha engineer Yoshiharu Nakayama first came up with the idea of creating the first competitive four - stroke race motocross bike. The Yamaha YZ400F was developed to fit into this category. It solved the power dilemma by borrowing superbike technology and giving the YZ a five - valve head, liquid cooling and a 12.5 - 1 compression ratio. In 1997, Yamaha rocked the motocross world with the introduction of the YZ400M prototype, a concept motorcycle which borrowed much technology from road racing. The YZM was far ahead of all competition among four - stroke motocross bikes. Doug Henry piloted the YZ400M to its first victory in 1997 at the Las Vegas Supercross. This was the first time any four - stroke had won an AMA event. The YZ400M was the predecessor of the production YZ400F, which was released the next year. First Generation YZ400F Production 1998 - 2000 Predecessor YZ250 2 - stroke Successor YZ426F Engine Five - valve, 400 cc, compression ratio 12.5 : 1 Transmission 5 - speed Weight 250 lb ( 110 kg ) ( dry ) First generation : YZ400F 1998 -- 2000 Yamaha introduced the YZ400F in production in 1998 after a successful AMA season in 1997. It was `` the first modern production four - stroke motocrosser that was directly competitive against two - strokes. '' Initially, Yamaha targeted a dry weight of 233 pounds ( 106 kg ) ( on par with the 250 two - strokes of the time ), but by production, the bike weighed 250 pounds. The bike had an 11,600 rpm redline power and torque close to its 250 cc two - stroke rivals. It benefited from engine compression braking, which allowed the engine to slow the bike down during deceleration, giving the brakes a rest. The 1998 YZ400F was the first bike to come stock with a Keihin FCR carburetor. In 1998, Doug Henry won the AMA National Motocross Championship aboard the YZF, becoming the first rider to win a championship on a four - stroke motorcycle. This victory is considered by some to be the major turning point in the motocross world -- for the first time, four strokes were considered a competitive racing machine. Second generation YZ426F Production 2000 - 2003 Predecessor YZ400F Successor YZ450F Engine Titanium five - valve, 426 cc, 95mm x 60.1 mm stroke, compression ratio 12.5 : 1 Transmission 5 - speed Suspension Kayaba Brakes Disks Wheelbase 58.7 in Fuel capacity 2.1 gallons ( 7.95 L ) Second generation : YZ426F 2001 -- 2002 In 2000, Yamaha updated the YZ400F, increasing the displacement to 426 cc for greater power and throttle response. In addition, the carburetor and jets were updated to ease the YZ400F 's starting woes. The next year, in 2001, Yamaha replaced the previous steel valves with titanium ones. The new valves were more than forty percent lighter than the previous valves, allowing for lighter and softer valve springs, in turn allowing a quicker revving engine, improved throttle response, higher rev ceilings, and more power. The crankshaft was also reshaped and the whole assembly was redesigned for quicker throttle response and, Yamaha claimed, `` less high - end horsepower loss. '' In addition to motor modifications, a few changes were made to the transmission to help contain the power and ensure longevity. The suspension also received a bit of an overhaul with the goal being reduced weight and smoother action throughout the stroke. Yamaha also designed a new exhaust pipe design so that exhaust header removal would no longer be required when replacing the oil filter. Carburetor tuning was modified to deal with starting and off - idle take off difficulties. Also in 2001 the subframe was changed from a steel to a blue painted aluminum style. In 2002 the blue painting was stopped and left to a bare aluminum look. Motorcycle.com says that `` The gas tank is reasonably thin and allows good forward and backward movement while providing something nicely shaped to hold onto with your knees. In fact, the entire ergonomic package on this YZF is well thought out. The handlebars have a nice bend to them and are well - placed for good rider control and legroom. The footpegs are well - made units with a wide platform and sit in a position that keeps them from dragging in ruts without cramping a rider 's legs. '' In 2002 Yamaha remapped the digital CD ignition system which delivers a more precise spark and optimal timing for faster, stronger response during hard acceleration, and less kickback during starting. Also an all - new swingarm which is lighter and stronger for reduced weight, greater rigidity and more compliant rear suspension action. While an anodized finish gives the bike a tricked out look. The 426 also includes a larger pivot shift for increased durability. A larger rear brake disc was also added which means greater stopping power. Third Generation YZ450F Production 2003 - 2005 Predecessor YZ426F Engine Titanium five - valve, 449 cc, 95.0 x 63.4 mm, compression ratio 12.3 : 1 Transmission 2003 - 2004 : 4 - speed 2005 : 5 - speed Frame type Steel Related YZ250F, WR450F Third generation YZ450F 2003 -- 2005 For 2003, the YZF received the biggest update in its history. First, the engine displacement was increased with 449 cc in compliance to the new AMA Motocross maximum displacement rule, the engine now produced over 52 hp ( 39 kW ). Next, the frame and plastic were updated for a new, sleeker look. Additionally, the YZF 's weight was decreased from its original 250 lb ( 110 kg ) to 233 lb ( 106 kg ). The bike made tremendous power ; however, many thought that the bike had too much power for a motocross track. The 2005 YZ450F was the first YZ450F to feature KYB twin chamber cartridge forks. Fourth generation YZ450F 2006 -- 2009 Fourth Generation YZ450F Production 2006 - 2009 Predecessor YZ450F Engine Titanium five - valve, 449 cc, 95.0 x 63.4 mm, compression ratio 12.3 : 1 Transmission 5 - speed Frame type Aluminum Fuel capacity 1.9 gal Related YZ250F, WR450F The YZ450F received a major update in 2006, with over 300 parts changed and improved. The power was smoothed out, and the bike was made easier to ride, putting to rest the complaint that the YZ had too much power. The transmission was returned to a more traditional five - speed. An all - new aluminum single backbone frame shaved another 10 pounds off the weight. The 2006 saw KYB SSS forks. 2007 saw camshaft and exhaust changes, moving power from low - RPMs to mid-RPMs. 2008 - 2009 furthered pushed the powerband to mid-RPMs. Fifth generation YZ450F 2010 - 2013 Fifth Generation YZ450F Production 2010 - Present Engine Rear slant, titanium four - valve, 449 cc, 97.0 mm x 60.8 mm stroke, compression ratio 12.5 : 1 Transmission 5 - speed Related WR450F, YZ450FX September 8, 2009, Yamaha introduced its all - new YZ450F with fuel injection. The engine cylinder is rearward slanted, the crank rod angle has been changed to provide a more complete combustion, the 5 - valve head is now a 4 - valve head, the gas tank is located under the seat, the exhaust pipe exits the rear of the cylinder, and the air intake is now in the front of the bike. They have a new bi-lateral frame which allows for new improved steering and the new engine components. The entire package comes together to create a bike that is mass - centralized. The bike was introduced by Yamaha Factory Motocross rider James Stewart. The top speed has been recorded at 80 mph stock. References ^ Jump up to : Lewis, Jimmy ( January 2002 ), `` The Main Event : Honda CRF450R lines up against KTM 520 SX and Yamaha YZ426F '', Cycle World, 41 ( 1 ), pp. 70 ff ( 8 ) Jump up ^ Hoffman, Scott ( February 2002 ), `` Concept 2003 YZ450F imminent future '', Dirt Rider, Primedia Enterprises, pp. 28ff ( 3 ), It was less than a year ago that innuendos regarding ' an all - new Yamaha YZ450F ' circumnavigated the motocross world. The gossip was far less shocking compared to when Yamaha first unveiled its works YZ400M in ' 97 and its plans to build a competitive motocross four - stroke, although it still held merit. This was also mixed in with Honda 's breaking news of its project four - stroke motocross bike, the CRF45OR. Nevertheless, Yamaha forged its name into the hooks five years ago and its revolutionary machine will forever be remembered as the catalyst that sparked the fire under the smoldering world of four - stroke motocrossers. Jump up ^ `` Titanium spring improves motocross motorcycles '', Advanced Materials & Processes, 164 ( 7 ), p. 9, July 2006, For model year 2006, the Yamaha YZ125 and YZ250 two - stroke and the YZ250F and YZ450F four - stroke motocross motorcycles all carry titanium shock springs, marking the first time production motorcycles from any manufacturer have been fitted with titanium suspension springs as original equipment, reports Timet Automotive, Morgantown, Pa. Yamaha claims the new springs offer `` outstanding strength and fatigue tolerance '' and reduce unsprung weight for improved suspension performance. ^ Jump up to : `` 2001 Yamaha YZ426F : MD Ride Review ''. motorcycledaily.com. Jump up ^ `` Page not found ! '' ( PDF ). www.amaproracing.com. Jump up ^ `` YZ426F : Miracle Machine ? -- Motocross News, Race Reports, Videos, Photos, Interviews, How - Tos ''. transworldmotocross.com. ^ Jump up to : Motorcycle Hall of Fame : Doug Henry Archived 2010 - 01 - 13 at the Wayback Machine. Jump up ^ GT Thunder Test Bench Jump up ^ `` Year 2001 Yamaha YZ426F ''. Motorcycle.com. 2000 - 10 - 27. Retrieved 2011 - 12 - 27. Jump up ^ `` Year 2001 Yamaha YZ426F ''. motorcycle.com. Jump up ^ `` New Yamaha Dirt Bikes For 2002 : Off-Road.com ''. Dirtbike.off-road.com. 2005 - 11 - 01. Retrieved 2011 - 12 - 27. Jump up ^ `` First Impression : 2004 Yamaha YZ450F -- Motocross News, Race Reports, Videos, Photos, Interviews, How - Tos ''. transworldmotocross.com. Jump up ^ `` 2006 Yamaha YZ450F - First Ride - MotorcycleUSA.com ''. motorcycle-usa.com. External links The Long History of Reverse - Cylinder Engine Designs - motocrossactionmag.com Yamaha motorcycles Standard XS400 XS500 XS650 XS750 XS850 XS1100 Yamaha XSR900 SR500 SRX 400 / 600 FZX250 FZX750 XJ600 / FJ600 XJ600 Diversion XJ900 XJ900 Diversion XJR400 XJR1200 Yamaha XZ550 XJR1300 YX600 Radian YBR125 FZ150i FZ16 FZ8 & FAZER8 FZ1 MT - 125 MT - 25 MT - 03 MT - 07 MT - 09 MT - 10 Sport TZR50 TZR125 TZR250 FZ700 FZ750 Fazer FZ400R RD250LC RD350 RD350LC RD500LC FZ750 FZR250 FZR400 FZR600 FZR750 FZR1000 YSR50 YZF600R YZF750 YZF1000R YZF - R6 YZF - R7 YZF - R1 YZF - R125 YZF - R15 YZF - R25 YZF - R3 SZR660 TRX850 FZS600 Fazer FZ6 M - Slaz MotoGP YZR500 YZR - M1 Touring / Sport touring Venture Royale FJ1100 FJ1200 FJR1300 GTS1000 Tracer 700 Tracer 900 Power cruiser V - Max / VMAX BT1100 Bulldog MT - 01 MT - 03 Cruisers XS Special 400 650 750 850 1100 XJ Maxim 400 550 650 700 750 1100 XV Virago 125 250 400 500 535 750 920 1100 XV Road Star / Wildstar 1600A 1600ALE 1600AS 1600AT ( Silverado ) 1600ATLE ( Silverado ) 1700A 1700AM 1700AT ( Silverado ) 1700ATM ( Silverado ) XV1900 XVS Drag Star / V Star 125 250 400 650 950 1100 1300 ( Midnight Star ) XVZ Royal Star 13A ( Royal Star / Boulevard ) 13AT ( Tour Classic ) 13LT ( Tour Deluxe ) 13TF ( Venture ) Supermoto XT660X Dual - sport / Enduro / Off - road XT125R XT125X XTZ 125 XT 225 TDR250 XT250 WR250F XT350 WR400F WR426F WR450F XT600E XT660R XT660Z Ténéré XTZ660 Ténéré XTZ750 Super Ténéré TDM850 XT1200Z Super Ténéré YZE750 YZE850T Agricultural TW200 AG100 AG175 AG200 Motocross YZ85 YZ125 YZ250 YZ250F YZ400F YZ426F YZ450F Scooter TMAX Aerox Lagenda Majesty Mio Nouvo QT50 Vino Classic Vino 125 X-City XF50X Zuma Zuma 125 V50M Tricycle Tricity First models Yamaha YA - 1 Yamaha DT - 1 Commons hide Yamaha motorcycle timeline, 1990s -- present Type 1990s 2000s 2010s 0 5 6 7 8 9 0 5 6 7 8 9 0 Standard \Naked FZX250 FZX750 XJ600 / FJ600 XJ600 Diversion XJ900 XJ900 XJR400 XJR400 XJR1200 XJR1300 YX600 Radian Sport TZR250 FZR250 FZR400 FZR600 Both FZR600 and YZF600R Both YZF600R and YZF - R6 YZF - R6 FZ750 FZR750 YZF750 YZF - R7 FZR1000 YZF1000R Both YZF1000R and YZF - R1 YZF - R1 SZR660 TRX850 FZ6 FZ1 MotoGP YZR500 YZR - M1 Touring Sport touring FJ1200 FJR1300 GTS1000 Power Cruiser V - Max VMAX BT1100 Bulldog MT - 01 MT - 03 Cruisers XV125 / Virago 125 XV250 / Virago 250 XV400 / Virago 400 XV500 / Virago 500 XV535 / Virago 535 ( US sales ended in 2000 ) XV750 / Virago 750 XV1100 / Virago 1100 XV1600 / Road Star / Wildstar XV1700 / Road Star Warrior XV1900 / Midnight Star / Roadliner XVS125 / Drag Star 125 / V Star 125 XVS250 / Drag Star 250 / V Star 250 XVS400 / Drag Star 400 / V Star 400 XVS650 / Drag Star 650 / V Star 650 V Star 950 XVS1100 / Drag Star 1100 / V Star 1100 XVS1300 / Midnight Star XVZ 1300 / Royal Star XVZ 1300 / Venture Royale XVZ 1300 / Royal Star Venture XVZ 1300 / Royal Star Tour Deluxe Supermoto XT660 X Dual - sport Off - road TDM850 TDR250 XT125 R XT125 X XT600 E XT660 R XTZ660 Ténéré XT660Z Ténéré XTZ750 Super Ténéré XT1200Z Super Ténéré Motocross YZ125 YZ250F YZ400F YZ426F YZ450F Retrieved from `` https://en.wikipedia.org/w/index.php?title=Yamaha_YZ450F&oldid=841876975 '' Categories : Yamaha motorcycles Off - road motorcycles Motorcycles introduced in 1998 Hidden categories : Webarchive template wayback links Pages using deprecated image syntax All articles lacking reliable references Articles lacking reliable references from May 2015 Talk Contents About Wikipedia Polski Português Edit links This page was last edited on 18 May 2018, at 17 : 07. 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Question: how many gears does a 2003 yz450f have
Answer: 4