For this version of Traditional Metal, we’re going to have a look again at Yamaha’s all-new 2003 YZ450F.
In 2003, Yamaha debuted its first main redesign of the machine that shocked the motocross world in 1998. Lighter, sooner, and extra hard-edged than earlier than, the all-new YZ450F was bred to win. Picture Credit score: Yamaha
In 1998, Yamaha kicked off the fashionable four-stroke revolution with the introduction of its ground-breaking YZ400F. Earlier than the YZ400F, most motocross four-strokes provided slow-building powerbands that chugged and churned fairly than barked and blasted. This fashion of energy was glorious off-road, however not all the time very best for the cut-and-thrust world of motocross. Mega thumpers just like the ATK605, Husqvarna TC610, KTM 620, and Husaberg FC501 had their followers, however the majority of mainstream motocross racers discovered them to be extra of a curiosity than a viable racing different.
The all-new 449cc motor on the YZ450F featured a extra compact head, longer stroke, and dozens of adjustments geared toward shedding weight and boosting energy. Picture Credit score: Yamaha
The place the YZ400F broke new floor was within the design of its motor. Through the use of a short-stroke and five-valve Genesis head from their highway racing division, Yamaha was in a position to imbue the YZ400F with a quick-revving fashion of energy that was utterly in contrast to another four-stroke motocrosser earlier than it. With its ultra-smooth powerband, the YZ-F may discover traction on almost any floor whereas nonetheless providing sufficient energy to outmuscle most of its two-stroke rivals. It was each remarkably quick and extremely simple to journey and shoppers snapped them up in droves.
An all-new cylinder for 2003 (proper) adopted methods used on Tim Ferry’s manufacturing unit bike by including cutouts to the decrease skirt to enhance crankcase stress venting and enhance responsiveness. Picture Credit score: Yamaha
Whereas the unique YZ400F proved an unbelievable business success, it was not with out its share of peccadillos. The YZ-F’s weight remained considerably larger than its two-stroke rivals and that heavy really feel by no means went away on the observe. Total dealing with was glorious, but when the massive blue machine acquired off form it was a handful to reign again in. Beginning the 400F was an journey by itself with the machine requiring an elaborate ritual that was tough to grasp and almost unimaginable to execute within the warmth of battle. Grabbing a handful of throttle was usually rewarded with a hiccup from the motor and having the machine hesitate at an inopportune second was a surefire recipe for bother. Technical bounce combos that have been simple to execute on an ultra-responsive two-stroke have been usually extra like taking part in Russian Roulette on the sometimes-unpredictable YZ-F. In comparison with each different four-stroke earlier than it, the YZ400F was a revelation, however that didn’t cease it from affected by lots of the similar drawbacks as its valve-and-cam predecessors.
A brand new body for 2003 shed three kilos of weight over the 2002. Picture Credit score: Yamaha
In 2000, Yamaha launched the primary main replace to their YZ-F platform within the type of the all-new YZ426F. Visually nearly equivalent to the unique YZ400F, the brand new 426 featured an all-new motor, revamped body, up to date suspension, and two-pound weight financial savings over 1999. The brand new motor displaced an extra 26cc and provided a very new persona on the observe. Whereas the unique YZ400F pumped out a {smooth} and electrical fashion of energy that pulled from the underside to the highest with none hit or drama, the brand new YZ426F barked out of the outlet and snarled by the center. The brand new motor was far more like a standard massive bore four-stroke in its persona and a major departure from the rev-happy 400F. On the time, most racers appeared to love this transformation and the YZ-F continued its domination of the big-bore four-stroke wars.
For 2003, Yamaha shrunk the scale of the exterior oil tank by 500cc and repositioned it decrease on the body to enhance weight distribution. Picture Credit score: Yamaha
Because the 2000s began, nonetheless, the YZ-F started to really feel a bit extra stress from its rivals. The all-new Cannondale MX400 turned out to largely be vaporware, however the KTM 520SX proved its mettle with a rompin’ stompin’ powerband and a 15-pound weight benefit over the YZ426F. Neither machine was able to unseating the Yamaha because the king of motocross thumpers, however the class was heating up.
The 185 adjustments Yamaha made to the YZ-F in 2003 added as much as a claimed 13.5-pound weight financial savings over the 12 months earlier than. This earned it the excellence of being the lightest machine within the class, however its massive energy and enormous really feel fooled many into pondering it was the heaviest. Picture Credit score: Transworld Motocross
In 2002, the facility construction of the four-stroke class lastly shifted with the introduction of Honda’s YZ-F competitor, the CRF450R. Using the third technology of their revolutionary alloy chassis and that includes an all-new “Unicam” motor design, the CRF450 addressed lots of the points four-stroke holdouts had voiced concerning the authentic YZ-Fs. Lighter, sleeker, smoother, and much simpler to start out than the YZ426, the CRF provided two-stroke converts an excellent simpler transition to life with out premix. Practically in a single day, beginning gates throughout the county have been awash in crimson Unicam machines.
By sticking with metal for the body’s building Yamaha was in a position to design a machine with far simpler entry to many of the main parts than on the CRF. Picture Credit score: Yamaha
With the large success of the CRF450R, it was fairly obvious that Yamaha would wish to step up its recreation to recapture the highest place within the four-stroke division. As aggressive because the YZ426F was, its XR-like weight, stale seems, infuriating beginning drill, and fondness for hesitation made it a troublesome promote when pitted in opposition to the easier-to-live-with Honda. Each machines have been able to profitable, however most riders discovered the CRF to be the superior machine of the 2.
for 2003, Yamaha was in a position to ease upkeep by including a secondary oil fill to the engine circumstances. Picture Credit score: Yamaha
With a lot revenue and status at stake, Yamaha got here able to play in 2003. The unique YZ-F platform was retired, and an all-new machine was launched to do battle with Honda’s extremely standard CRF. In all, Yamaha made 185 distinct adjustments within the transition from the YZ426F to the reimagined YZ450F. Weight saving was a serious focus of the brand new design and Yamaha’s engineers checked out each element for a strategy to save just a few valuable ounces.
An all-new rear brake meeting lowered weight by shrinking the caliper measurement and integrating the grasp cylinder and fluid reservoir into one unit. Picture Credit score: Motocross Motion
On the motor entrance, Yamaha retained the identical fundamental DOHC structure and five-valve head it had used since 1998 however added 3.3mm of stroke to lift displacement to 449cc. An all-new cylinder shed weight by dropping two bolts from the cylinder base and the brand new head lowered the middle of gravity by lowering its top by 7mm. The valves remained titanium in building however have been barely shorter and 18% lighter than in 2002. Paired with the brand new valves have been extra compact springs and repositioned cams that allowed for a straighter valve angle inside the head. A brand new computerized decompression system lastly made its strategy to the valvetrain to simplify beginning and convey it on par with the Honda and KTM.
An all-new exhaust for 2003 shed kilos by shifting to titanium for the pinnacle pipe, warmth protect, and finish cap. Picture Credit score” Yamaha
A brand new crankshaft meeting lowered weight by 20% and a 7% lighter piston was added to enhance motor response. In a nod to Tim Ferry’s works machine, new cutouts have been added to the cylinder skirt to scale back pumping stress and additional liberate the highest finish. The cam-chain tensioner, oil pump, CDI, ignition coil, and flywheel have been all gotten smaller to decrease weight and shrink the general footprint of the motor. A brand new consumption saved 12 ounces by redesigning the clamps to be inner. All of the oil traces have been moved from metal to aluminum as nicely to avoid wasting just a few extra ounces. In one other nod to the works Yamaha machines the transmission was moved from a five-speed to a four-speed in 2003. Yamaha claimed the brand new transmission was each lighter and stronger than the previous five-speed with new ratios designed to reap the benefits of the brand new motor’s extra torque. A brand new airbox shed 12 ounces and a redesigned exhaust swapped out metal for titanium in most of its main parts.
Whereas US-bound YZ450Fs maintained the standard finish cap design of earlier machines, bikes headed for different markets acquired an enclosed exhaust tip geared toward bettering rider security in a crash. Picture Credit score: Yamaha
On the chassis entrance, the YZ450F was simply as all-new and improved. The redesigned body shaved three kilos off of 2002’s by the usage of thinner cross tubing, a tapered steering head, and a smaller oil tank. A brand new rear brake lowered weight by adopting Honda’s built-in grasp cylinder and lowering the scale of the caliper and piston. Up entrance, a brand new aluminum caliper piston improved really feel and additional shaved ounces. An all-new swingarm featured a tapered design and smaller axle blocks to avoid wasting 80 grams. Even the chain slider was redesigned to avoid wasting 25 grams.
Former manufacturing unit rider and 1991 San Jose Supercross winner Doug Dubach performed a serious position within the growth of the all-new YZ450F. Picture Credit score: Yamaha
On the suspension facet, a brand new shock saved 40 grams of weight and was paired with an eight-ounce lighter spring. The spring charge remained unchanged from 2002 however a better grade of metal was used to scale back weight. Internally, the brand new shock was just like 2002’s except for the usage of lighter-weight supplies inside. Up entrance, the YZ450F retained the Kayaba bumper forks it had utilized in 2002 however added new valving, a redesigned damper rod, and new stanchions with much less taper to enhance really feel.
Timmy Ferry was Yamaha’s prime gun on the YZ450F in 2003. Picture Pic: Simon Cudby
Visually, the most important change for 2003 was the YZ450F’s all-new bodywork. This was the primary main replace of the YZ-F’s look since its 1998 debut and Yamaha took the chance to make main adjustments to its structure and really feel. Every part from the fenders to the facet plates was all-new with a decrease, thinner, and flatter really feel all through. The brand new tank was narrower and fewer intrusive with a lowered capability of 1.85 gallons from the earlier 2.1 gallons. This allowed simpler rider motion and saved 10 ounces. The seat was flatter by the center and slimmer on the entrance making it simpler to slip ahead in turns. The brand new facet plates remained very massive and continued to include helpful cutouts to assist in lifting the machine when vital. Altogether, the numerous adjustments Yamaha made to the YZ450F for 2003 added as much as a claimed 13-pound weight financial savings over the 2002. When MXA weighed the 2 bikes filled with gasoline and able to race the true quantity grew to 18 kilos! This was an unbelievable distinction year-over-year and a testomony to how a lot effort Yamaha put into trimming weight on the YZ-F. At a claimed 232 kilos, the brand new YZ450F undercut each the CRF450R and KTM 450SX in 2003 and leapfrogged the YZ-F from the portliest machine within the class to essentially the most svelte of all of the 450 choices.
The brand new YZ450F was a superb handler in 2003. Nice turning and rock-solid stability made the machine a pleasure to shred on a freshly groomed observe. It was solely when the traction dried up that the bike turned a little bit of a handful. Picture Credit score: Dust Rider
On the observe, all of those adjustments added as much as a sooner, leaner, and extra severe machine. Whereas the ’02 YZ426F was no slouch within the energy division, it was no comparability to the fire-breather Yamaha produced in 2003. The brand new 449cc DOHC mill revved sooner, hit more durable, and pulled longer than ever earlier than. It barked off the underside, exploded within the midrange, and pulled until the cows got here dwelling on prime. Not like the CRF, which was {smooth} and nice, the YZ-F was all hearth and brimstone. On the dyno, it pumped out three extra horsepower than the Honda and each a kind of ponies was obvious any time you twisted the throttle. It revved quick, hit onerous, and demanded consideration to maintain issues below management. The brand new motor did away with plenty of the “chug” of the YZ426 and never everybody was a fan of the change. The occasional low RPM stumble remained, however it was less-pronounced than on earlier YZ-Fs. With the brand new motor, there was much less compression braking as soon as the throttle was closed however the engine was more durable to manage below energy and loads simpler to stall. Not less than in the event you did stall it was now not a nightmare to get relit. The brand new computerized decompression system did away with the flowery beginning drill of its predecessors and introduced the Yamaha on par with its kick-and-go rivals.
In 2003, this 449cc DOHC single was the grasp blaster of the four-stroke division. With a lightweight flywheel, an explosive midrange hit, and gobs of top-end energy, the YZ450F was an expert-level motor that was simply an excessive amount of for a lot of to deal with. Professionals beloved its pull, however mere mortals wanted a heavier flywheel and an excellent little bit of throttle self-discipline to maintain its fury below management. Picture Credit score: Motocross Motion
In comparison with a typical 250 two-stroke, the YZ450F provided glorious hookup, however when pitted in opposition to a KTM or Honda four-stroke, the YZ-F was a handful. Its onerous hit and a quick spin-up made throttle management crucial and the bike may very well be loads for much less skilled riders to deal with. If there was deep soil and tons of traction the YZ450F was a dream with gobs of usable energy on faucet. If, nonetheless, the observe was onerous and slick, the Yamaha demanded extra care with the throttle than its rivals to place all that energy to the bottom. With a lot muscle on faucet, most racers didn’t miss the extra gear within the transmission, however many felt the bike would have benefitted from a barely heavier flywheel. Including some weight to the flywheel smoothed out the explosive hit, aided hookup, and lowered stalling. With this addition, the fire-breathing YZ-F turned a way more livable companion. Whereas off-road riders have been by no means going to like the four-speed transmission, with a heavier flywheel and a few fine-tuning to the gearing it was not a difficulty for motocross.
a brand new four-speed transmission saved weight however proved polarizing with the general public. The shortage of a fifth gear turned off informal riders and even some moto heads thought the gear spacing it offered was not very best. Picture Credit score: Stefan LeGrand
On the suspension entrance, the YZ was rated nicely in most classes. The brand new valving offered a barely firmer really feel and the bike was well-balanced general. Up entrance, the Kayaba forks offered 11.8 inches of journey and exterior changes for compression and rebound damping. In inventory situation, they have been well-sorted and stiffer feeling than the CRF’s Showa parts however nonetheless compliant sufficient to take the chew out of most observe obstacles. Bottoming was not a difficulty and most riders beneath the professional class may get by and not using a revalve or spring swap. Lighter and slower riders discovered the plusher really feel of the Honda parts preferable however for severe racers, the YZ-F’s extra aggressive forks settings have been an excellent match.
In 2003, there have been three main contenders within the 450 division. The KTM provided high-quality parts and a {smooth} engine however was hamstrung by a poor shock and four-speed transmission. The Yamaha featured the lightest weight and most horsepower however delivered it abruptly with the identical four-speed points that restricted the KTM. For a lot of, the Honda’s mixture of easy-to-use energy, five-speed versatility, good-enough dealing with, and supple suspension made it the bike to beat. Picture Credit score: Dust Bike
Within the rear, the YZ-F was as soon as once more ranked at or close to the highest of the category. The inventory shock settings have been agency, and the rear delivered a well-controlled journey in most conditions. It was fairly compliant on small chop and glorious at coping with massive hits. This was an enormous enchancment over earlier YZ-Fs which frequently felt undersprung for his or her substantial weight. Simply as with the forks, the KYB shock was not as plush because the inventory CRF, however most quick guys most popular the firmer really feel of the Yamaha. The brand new thinner seat didn’t present plenty of cushioning, nonetheless, and various riders complained of a sore bottom after a day on the YZ-F.
The 46mm Kayaba fork on the YZ450F delivered a agency however well-controlled journey that was good for attacking the observe. Slower riders may need most popular the plusher settings discovered on the Honda, however for severe racers, it was a superb fork. Picture Credit score: Yamaha
On the dealing with entrance, the YZ450F continued to be an excellent all-around machine. Turning precision was glorious with the mix of the motor’s sturdy compression braking, well-sorted suspension, and glorious chassis design offering an distinctive front-end really feel. The brand new flatter seat and slimmer tank made it simpler than ever to get ahead in turns and the YZ-F may very well be trusted to carry its line with none concern of an surprising washout. In most circumstances, the YZ-F cornered prefer it was on rails and the bike was surprisingly adept at altering course for such an enormous and highly effective machine.
Metal bars have been nonetheless normal tools on Japanese machines in 2003. Picture Credit score: Yamaha
Whereas the YZ-F’s front-end traction was exemplary, it may very well be a bit tough to handle on the exit of turns if the observe was onerous and slick. In these circumstances, the machine demanded respect and it was necessary to train restraint to forestall breaking the rear finish free. The YZ-F’s sudden supply and monster hit made discovering traction in these conditions extra of a problem than on its rivals and the blue bruiser was recognized to hold its tail out abruptly if the pilot was ham-fisted with the throttle. The inventory seat was additionally fairly slippery, and lots of riders thought the YZ-F may have used a extra grippy seat cowl. With out it, it was a continuing battle to maintain your weight ahead because the Yamaha’s megatons of thrust tried to tug you off the again. Very similar to an old-school 500 two-stroke, conserving the Why-Zed a gear excessive and being {smooth} with the throttle have been the most effective strategies to maintain the sometimes-unruly machine in line.
The rear suspension on the YZ450F was probably the greatest setups on the observe in 2003. Its mixture of compliance and management allowed the Yamaha’s pilot to pin it by the tough with none concern of a sudden kick or swap. Picture Credit score: Stefan LeGrand
At pace, the YZ-F was in its factor and the bike was glorious at gobbling up massive swaths of observe in a rush. Even and not using a fifth gear, the YZ-F was able to quasar speeds and the bike was a bullet practice when it constructed up a head of steam. There was not even a touch of headshake and nothing in need of an act of God was more likely to knock the Yamaha off its meant path. Apparently, although the Yamaha was considerably lighter than earlier than, it didn’t really feel as mild as the dimensions proclaimed it to be. Regardless of its 232-pound weight, it felt heftier than the 235-pound CRF and KTM on the observe. It was a considerable enchancment over the previous YZ426F, however riders have been by no means going to mistake the massive and highly effective YZ450F for something however the Open bike that it was.
Excessive-speed sweepers have been a chunk of cake on the YZ450F so long as you didn’t get too carried away with the loud deal with on the exit. Right here PulpMX’s personal Kris Keefer places all these luscious vibes to the bottom for Bryan Nylander’s digicam. Picture Credit score: Dust Rider
On the detailing entrance, the YZ450F was glorious in most respects. Along with being the powerhouse of the category, Yamaha’s five-valve DOHC motor proved to be by far essentially the most dependable. Its small and light-weight titanium valves required much less upkeep than the Honda and the dry-sump motor’s extra oil capability gave it a margin of error not discovered on the CRF. So long as you modified the oil and cleaned the air filter repeatedly, the YZ450F was as bulletproof as any racing machine had a proper to be. Its air filter was additionally far simpler to entry than the one discovered on the CRF. Each, nonetheless, have been disappointing when in comparison with the toolless entry provided by the KTM. Off-road fans and extra informal riders hated the four-speed transmission, however most racers didn’t discover it an enormous hindrance for motocross. Some riders did complain that it sometimes felt “between gears” however it shifted nicely and many of the gaps may very well be managed with gearing adjustments geared toward particular person observe conditions. Whereas the four-speed labored nicely sufficient, many pit pundits thought deleting the fifth gear was an odd alternative by Yamaha. It tremendously hindered the YZ450F’s enchantment for something apart from observe use and contemplating shoppers usually purchase 450s for his or her versatility, the pound or so of weight financial savings it yielded appeared like a poor tradeoff to many.
An all-new carburetor for 2003 moved the hot-start circuit to the handlebars for added comfort. Picture Credit score: Motocross Motion
Whereas not as trick-looking because the Honda’s aluminum body, the Yamaha’s metal body building did have its benefits. With out the Honda’s large aluminum spars, entry to the motor and carburetor was a lot improved. The bike was additionally barely thinner by the center with out the body getting in the way in which. Cosmetically, all three 450s have been good-looking when new, however the painted body, darkish blue plastic, and flimsy graphics of the Yamaha tended to indicate their age far faster than the competitors. The powder-coated body of the KTM and the naked aluminum chassis of the CRF appeared new longer and each provided graphics that proved extra strong below onerous use. The butter-soft metal bars, flimsy inventory sprockets, and stretch-prone chain have been all de rigueur for Japanese bikes of the time and all three paled compared to the higher-quality parts discovered on the KTM. The YZ-F continued to make use of a fairly convoluted entrance brake routing (attributable to Honda patents) however its efficiency was glorious. The brakes have been highly effective entrance and rear and the brand new built-in rear grasp cylinder appeared to keep away from the overheating points that plagued the Honda’s transfer to this technique. With its highly effective brakes and tons of compression braking, the YZ-F was a tough machine to out-brake regardless of its massive measurement.
A redesigned pilot’s compartment for 2003 provided a flatter seat and slimmer profile. Whereas the brand new seat made it simpler to slip fore and aft, its skinny foam and onerous really feel offended many a bottom. Picture Credit score: Yamaha
Total ergonomics have been praised with the brand new structure providing a flatter and slimmer really feel that did away with the “pocket” that trapped some riders in place on the earlier mannequin. Some riders thought the seat-to-peg relationship was a bit cramped, however it match most pilots very nicely. Whereas the bike was simpler to maneuver round on for 2003, many riders have been much less enthusiastic concerning the new seat which was noticeably much less snug than the previous model. The redesigned seat featured foam that was very skinny and agency with the plastic base being noticeable on onerous landings. Each the KTM and Yamaha’s seats in 2003 have been akin to sitting on barely padded bricks and almost everybody most popular the cushier Honda’s lodging. The grips, levers, shifter, and operating gear have been all top-notch with a snug really feel and {smooth} motion. With the hot-start moved to the bars and its computerized compression launch, the YZ-F moved from the toughest bike to begin to one of many best. Usually, one good kick was all it took to get the massive blue beast lit. After 5 years of beginning drill distress, this was a TREMENDOUS enchancment for anybody pondering of shopping for a YZ-F.
In 2003, Yamaha constructed the lightest, quickest, stiffest, and most severe YZ-F but, however not everybody was as much as dealing with its Herculean nature. Picture credit score: Stephan LeGrand
Total, the brand new Yamaha YZ450F turned out to be a little bit of a polarizing machine in 2003. With its well-sorted suspension, glorious dealing with, rocket-fast motor, and lighter weight it was simply the machine many riders had been eager for the blue group to supply. Straightforward to start out, nicely put collectively, and stone dependable, the YZ-F had loads to supply, however it required loads in return. Not a machine for placing round or taking part in, the YZ450F was a brutish bike constructed to win on the observe on the expense of all the things else. Laborious, stiff, quick, and razor-focused, the YZ450F was a hairy-chested beast of a machine that demanded respect however delivered efficiency by the megaton.
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