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HomeMotocross“Maxxis Tires” – Traditional Metal #197 “1999 Yamaha YZ250” – PulpMX

“Maxxis Tires” – Traditional Metal #197 “1999 Yamaha YZ250” – PulpMX

For this version of Traditional Metal, we’re going to look again at Yamaha’s revamped 1999 YZ250.

At first look the 1999 YZ250 appeared little modified from the yr earlier than however beneath these Daring New Graphics beat the center of a winner. Photograph Credit score: Yamaha

The 1998 season was an enormous one for Yamaha. Jeremy McGrath introduced the model its first 250 Supercross title since 1980, John Dowd secured Yamaha a 3rd straight 125-West Coast SX crown, and Doug Henry captured the 250 Nationwide Motocross title on the all-new YZ400F four-stroke. The Blu Cru dominated racing in 1998 with a superb lineup of machines that delivered race-winning efficiency.

By far essentially the most important replace on the YZ250 for 1999 was its all-new 249cc motor. All the things from the bore and stroke to the facility valve design was all-new and engineered to carry the underpowered YZ as much as snuff with its rivals. Photograph Credit score: Yamaha

Within the magazines, Yamaha’s 1998 YZ400F and YZ125 had been the darlings of their respective lessons. The revolutionary YZ-F four-stroke broke new floor for Open class efficiency and the venerable YZ125 continued its dominance of the 125 division with its unbeatable mixture of broad energy and blistering acceleration. Within the 250 class, nonetheless, the YZ’s fortunes had been much less extraordinary. Revamped in 1996, Yamaha’s deuce-and-a-half was aggressive, however not a standout towards its rivals. With a motor that would hint its roots again to the Nineteen Eighties, Yamaha’s YZ250 was simple to experience however not notably thrilling. It lacked the “proper now” burst of Kawasaki’s KX250 and the “rev it to the moon” top-end pull of Honda’s CR250R. Its energy was broad and nice, its suspension was effectively sorted, and its dealing with was center of the highway. It was an ideal do-it-all bike for riders who prized total competence and ease of use over tire-shredding efficiency.

Except for modifications required to accommodate the brand new motor the YZ’s body was unchanged from the yr earlier than. The Why-Zed was already thought to be one of many best-handling machines within the class and Yamaha selected to keep up the identical geometry for 1999. Photograph Credit score: Yamaha

In 1999, Yamaha appeared to carry a little bit of pizzazz to their quarter-liter racer by introducing their first all-new 250 motor design in almost twenty years. Since 1982, Yamaha had relied on a rotating-drum energy valve variable exhaust design they coined the YPVS (Yamaha Energy Valve System). The YPVS was groundbreaking in 1982 and the primary variable exhaust port design to make it to manufacturing. Finally, nonetheless, extra superior twin and triple valve designs had been launched that delivered broader energy and extra peak efficiency.

An all-new crank for 1999 was lighter and featured an extended stroke than prior to now. The brand new piston was lighter and maintained a double-ring design for optimum sealing and longevity. Photograph Credit score: Yamaha

In 1995, Yamaha added an exhaust resonance chamber to the YPVS to broaden the YZ’s powerband, however it continued to lag behind powerhouses just like the Honda CR250R in peak motor efficiency. The YZ250’s powerband was vast and straightforward to experience, however not as quick as a few of its competitors in inventory situation. With its do-it-all dealing with and well-sorted suspension many riders nonetheless felt the YZ was a superb machine, however the time for an all-new motor was rapidly approaching.

The YZ’s all-new motor lastly did away with the rotating drum energy valve design Yamaha had been utilizing on their 250 machines since 1982. The brand new energy valve design featured a single guillotine-style foremost valve and two smaller valves for the exhaust enhance ports for extra exact exhaust management. Photograph Credit score: Yamaha

The ’99 YZ’s carburetor was all-new and featured a solenoid-controlled “Energy Jet” that fed further gasoline to the motor under 8000 RPM to spice up low-to-mid response.

In 1996, Yamaha launched an redesigned YZ250 that moved the machine ahead in each means however one. All-new from the bottom up, the 1996 YZ improved dealing with and ergonomics, and to most rider’s eyes, the looks of Yamaha’s venerable YZ250 was improved by an all-new look. Up to date bodywork launched Yamaha’s new blue shade pallet and provided a slimmer and sleeker profile. The brand new chassis was stiffer and extra correct with the YZ providing probably the greatest mixtures of turning prowess and high-speed stability within the class.

Probably the most important change to the YZ250’s chassis for 1999 was an all-new linkage and swingarm that repositioned the shock mount to be 12mm decrease on the chassis and shaved half a pound on the scales. Photograph Credit score: Yamaha

In 1998, one of many greatest tales in motocross was Jeremy McGrath’s transfer to Yamaha after a disappointing season on Suzukis. As soon as on the blue machines, Showtime was rapidly again to his outdated type and carded Yamaha its first Supercross title since Mike Bell in 1980. Photograph credit score: Yamaha

The place issues went astray for the brand new YZ was within the motor division. The YZ was underpowered in comparison with its competitors and simply lower than operating with the most effective machines within the class. Modifications made to the powerplant for 1996 narrowed its beforehand broad supply and at its peak, it gave up almost 4 horsepower to the category leaders. In some ways, the brand new blue YZ was an enchancment, however with out the firepower to run on the entrance, it slipped from one of many class leaders to the caboose of the 1996 250 area.

An all-new rear wheel for 1999 added Takasago Excel rims, bigger spoke nipples, a redesigned sprocket mount, and a 2mm bigger rear axle. Photograph Credit score: Motocross Motion

In 1997 and 1998, Yamaha refined the YZ250 package deal with motor, chassis, and suspension updates that improved its competitiveness. The engineers rolled again the modifications made to the motor in 1996 and that resulted in a much wider however nonetheless not blisteringly quick energy plant. The vast powerband was simple to experience and glorious for less-skilled riders however its continued lack of holeshot-grabbing horsepower held it again within the last standings. Most riders appreciated the YZ’s versatile chassis and well-sorted suspension however with out extra horses on faucet, it was by no means going to outclass powerhouses like Kawasaki’s glorious KX250.

Employed Gun: One of many extra attention-grabbing controversies of the 1999 season was Kevin Windham’s shocking departure from Yamaha to Honda. Initially set to be underneath contract for the ’99 season, Windham appeared prominently in Yamaha’s promoting for the brand new YZs then abruptly left the model (reportedly over disputes with administration relating to the presence of his girlfriend within the group semi) to signal a 2-year take care of Honda. Yamaha sued Windham for Breach of Contract seeking to recoup the price of the shiny and dear seven-page advert. Finally, the 2 events settled out of court docket for an undisclosed quantity. Photograph Credit score: Yamaha

For 1999, Yamaha’s engineers lastly obtained the inexperienced mild to scrap their well-worn motor design and begin contemporary with an all-new engine. The brand new motor was redesigned from the bottom up with every little thing from the position of the crankshaft to the angle of the cylinder rethought to optimize efficiency. The crankshaft was repositioned to sit down 13mm decrease within the circumstances whereas additionally being bigger in diameter and lighter total. The connecting rod was redesigned with a smaller diameter decrease bearing and thinner development to save lots of weight. The piston was all-new and lighter with a shorter wrist pin and barely smaller diameter. The brand new motor reconfigured the bore and stroke from the outdated motor’s 68mm x 68.8mm to the identical 66.4mm x 72mm employed on Honda’s CR250R. The highest-end was all-new with a smaller diameter head, an all-new energy valve system, and a extra vertically organized placement. The outdated cylinder cantered ahead at 10.7 levels whereas the brand new ’99 design sat at an almost vertical 2.5 levels. The brand new cylinder retired the unique Yamaha Energy Valve System design in use since 1982 and launched an all-new triple-valve design that featured a guillotine-style foremost valve with two further valves to regulate the exhaust enhance ports. The ball-ramp governor that managed the facility valve was redesigned by rising the dimensions of the balls and reshaping the cup for extra exact management of the mechanism.

An all-new silencer for 1999 added an enclosed resin finish cap that Yamaha claimed was much less more likely to pack with grime within the occasion of a crash. Photograph Credit score: Motocross Motion

In 1998, one of many nice surprises on the all-new YZ400F four-stroke was the silky-smooth operation of its transmission. Lengthy a Yamaha bugaboo, notchy gear engagement had been a YZ custom for over twenty years. For 1999, the YZ250 adopted the 400F’s transmission design with bigger shafts and redesigned shift forks that had been pinned to the shift shafts. The transmission remained a five-speed with ratios similar to the 1997 YZ250. The clutch remained largely unchanged, however the actuator was repositioned contained in the ignition cowl and a brand new O-ring seal changed the outdated gasket on the clutch cowl to ease upkeep. The clutch cable was lowered in diameter by 0.5mm to enhance really feel and cut back weight. The oil filler gap was enlarged to make oil modifications simpler.

An all-new shock for 1999 featured elevated journey, new valving, and enlarged nitrogen quantity to combat fading. Photograph Credit score: Yamaha

On the consumption aspect, an all-new 38mm Keihin carburetor was put in that added a “Energy Jet” circuit for elevated response at low RPM. First launched by Honda on the 1997 CR250R, the Energy Jet was an extra gasoline circuit within the carburetor that was managed by a solenoid that enriched the gasoline combination at low RPM. At 8500 RPM, the solenoid lower off gasoline to this extra circuit to forestall the motor from operating too wealthy and lowering efficiency at excessive RPM.

All-new circumstances for 1999 moved the clutch mechanism to a Honda-like inside location contained in the ignition cowl. Photograph Credit score: Motocross Motion

Powering the Energy Jet was an all-new digital ignition that featured 3-D mapping and a revamped 8-bit CPU (the 1998 YZ250 used a 4-bit CPU) for extra exact ignition management. Exhaust duties had been dealt with by an all-new pipe with thinner stampings to cut back weight and a redesigned profile to enhance energy. A brand new silencer added a flush resin finish cap to cut back the possibility of the stinger packing with grime or inflicting an harm in a crash.

Jeremy Mcgrath was as soon as once more again to his successful methods in 1999 on the revamped YZ250. He would seize eight victories on his Mazda Chaparral Yamaha on his strategy to the 1999 AMA 250 Supercross title. Photograph Credit score: Dust Bike

On the chassis entrance, the YZ was new however not as radically up to date. The brand new body featured a number of modifications wanted to accommodate the brand new motor, however the total geometry was similar to 1998. The largest change to the chassis was the all-new swingarm which was a half-pound lighter than in 1998 and featured all-new castings and a repositioned decrease shock mount. The axle plates had been redesigned as effectively and manufactured to just accept a 2mm bigger rear axle for 1999. A brand new linkage for ’99 retained the identical rising charge as 1998 however featured a mechanical benefit over the outdated design by repositioning the angle and placement of the shock mounting. Except for the brand new swingarm and linkage, essentially the most important body change was the brand new footpeg bracket that relocated the footpegs 3.5mm nearer the body and lowered weight barely.

Redesigned circumstances for 1999 made servicing simpler by enlarging the oil fill gap significantly and shifting from a gasket to a reusable O-ring for the clutch cowl. Photograph Credit score: Yamaha

Paired with the brand new linkage was an up to date Kayaba shock with 15mm of further journey, elevated fuel capability, and up to date valving. The extra fuel capability was designed to cut back fading and the prolonged journey and relocated linkage had been employed to supply smoother efficiency underneath braking. The revised valving was set as much as supply freer motion of the shock at sluggish speeds whereas offering higher resistance to bottoming on laborious hits. Whole journey clocked in at 12.4” with exterior changes out there for compression and rebound damping.

New forks for 1999 featured stronger outer tubes and revamped valving. Whereas their preliminary journey was plush, most laborious chargers discovered their inventory springs and valving too comfortable for severe motocross use. Photograph Credit score: Yamaha

Up entrance, the 1999 YZ250 employed a considerably revised KYB fork with stronger outer tubes and lowered friction within the piston, seals, and bushing areas. The brand new silverware maintained the “bumper-style” design for the bottoming system however added up to date valving with further high-speed compression damping and a revised blow-off valve. To additional save weight the outer tubes had been tapered and the nut on prime of the cartridge valve was modified to aluminum.

By far the largest enchancment on the YZ250 for 1999 was its all-new motor. Clean, snappy, highly effective, and broad, it was an enormous enchancment over the mellow YZ powerplants of the earlier three years. Photograph Credit score: Yamaha

Bodywork remained unchanged from 1998 aside from the good-looking new “works” graphics that mimicked the designs seen on the 1998 manufacturing unit Yamaha machines. The bars, seat, and brakes had been all carryovers. New wheels entrance and rear added Takasago Excel rims, a 2mm bigger axle within the rear, 1mm bigger spoke nipples, and lighter weight hubs. All advised, Yamaha’s weight-saving measures for 1999 added as much as a 2-pound discount in weight.

After three years of sucking on the purple, yellow, orange, and inexperienced vapor trails of the competitors, the YZ was again within the horsepower sweepstakes in 1999. Photograph Credit score: Motocross Motion

On the monitor, the revamped YZ250 proved to be probably the greatest 250s of 1999. The brand new motor was head-and-shoulders higher than the 1998 energy plant with an extremely vast powerband and hooked-up supply. Throttle response was glorious with a a lot livelier really feel than prior to now. The brand new motor picked up quick and revved extra rapidly whereas by no means feeling abrupt or troublesome to regulate. The low-end energy was not as sturdy because the burly KX and the midrange hit was much less abrupt than the shoulder-tugging CR, however no different bike within the class provided the Yamaha’s mixture of outright energy and ease of use. It retained the sleek supply of 1998 whereas pumping up the facility considerably. Low-to-mid energy was considerably improved with a robust surge off idle and a wholesome midrange hit. The highest-end pull was good, however the YZ was happier if you happen to grabbed the following gear fairly than conserving it pinned till the cows got here dwelling. Grabbing that subsequent gear was additionally a lot simpler than prior to now because of the YZ400F-style transmission. For the primary time within the YZ’s historical past, a Yamaha 250 provided the smoothest and most optimistic shifting within the class. Missed shifts had been unparalleled and shifting underneath energy was not a hit-or-miss affair. The Yamaha’s clutch remained vaguer in its engagement than the wonderful Honda unit, however total, the YZ’s motor proved probably the greatest out there in 1999.

The all-new shock on the YZ250 provided a luxurious and managed experience that was higher sorted than the undersprung and underdamped entrance forks. Most riders felt the shock was raceable in inventory situation with solely minor fine-tuning of the clickers. Photograph Credit score: MX Racer

On the dealing with entrance, the YZ as soon as once more nailed the most effective mixture of dealing with precision and high-speed stability within the class. The YZ’s turning was glorious with manners that a number of riders ranked on the prime of the 250 division. The entrance finish caught like glue within the turns and the YZ was predictable in excessive and slow-speed corners. At velocity, the YZ was rock stable as effectively with the blue machine not often exhibiting a shake or wobble. At 228 kilos, the YZ gave up 6 kilos to the CR, however the Yamaha’s extra compact chassis and snappy motor made it really feel lighter than the dimensions indicated. Within the air and on the bottom, the YZ exhibited a nimble really feel that made it simple to jump over bumps and clear difficult jumps. The YZ’s compact ergonomics made it a bit cramped for NBA sorts, however for many riders, the YZ provided one of many best-handling chassis within the class.

At 228 kilos the YZ was removed from the lightest bike within the class, however its glorious ergonomics and snappy motor made it really feel like one of many lightest. Whips and jumps had been a pleasure on the YZ as soon as the comfortable entrance forks had been addressed. Photograph Credit score: Yamaha

Whereas the YZ’s chassis was universally praised, not everybody was in love with its up to date suspension. The entrance forks provided a comfortable really feel that much less skilled riders loved however consultants discovered lacked management. Regardless of coming with comparatively stiff .43kg/mm inventory springs, most riders felt the forks wanted stiffer coils to forestall bottoming and steadiness out the chassis. In inventory situation, the forks provided a comfortable really feel that was good at gobbling up monitor detritus however massive whoops and massive jumps rapidly overwhelmed its inventory settings. Slower riders cherished this comfortable really feel however as soon as the speeds ramped up their lack of management turned obvious.

In 1999, Jeremy McGrath moved to a Supercross-only schedule that allowed him to take the summers off to recharge his batteries. Whereas the Motocross collection was not his focus McGrath nonetheless confirmed he had the velocity to run on the entrance main a superb little bit of the Glen Helen spherical earlier than clutch points slowed the 1995 250 Motocross champ. Photograph Credit score: Motocross Motion

Within the rear, the brand new shock was extra universally praised for its plush really feel and glorious monitoring within the tough. It was noticeably firmer than the entrance forks whereas nonetheless providing glorious consolation and management. Huge jumps and whoops had been no concern and the YZ might deal with novices and professionals with out too many complaints. In inventory situation, the comfortable forks and stiffer shock hindered the YZ’s chassis steadiness, however as soon as the entrance springs had been upgraded and the clickers dialed within the YZ’s suspension was a prepared motocross companion.

The YZ’s brakes labored very effectively, providing glorious energy and management. Photograph Credit score: Yamaha

On the detailing entrance, the YZ was a largely well-thought-out machine. The blue plastic appeared nice when new however proved a lot much less abuse-friendly than the outdated white shade scheme had been. Scuffs and scratches had been readily seen and any time the plastic was bent it confirmed ugly white creases. The inventory graphics had been additionally of abysmal high quality with many of the stickers giving up the ghost by the third experience. The ergonomics had been glorious for many average-sized pilots with a compact really feel and slim structure. The seat was a bit skinny on the rear however total, it was way more comfy than the laborious Honda and KTM saddles. Taller riders benefited from taller foam however sadly, the inventory clamps didn’t function reversible bar mounts, so an aftermarket clamp was essential if you happen to wanted a bit extra room within the pilot’s compartment. The inventory radiator shrouds additionally continued to be an aggravation for knee brace wearers with its tendency to hook and bend out the rearmost nook. The brand new bigger oil fill gap was a blessing to mechanics as was the reusable O-ring employed on the up to date clutch cowl. The clutch itself labored decently however clutch abusers rapidly discovered that it was much less strong than a few of the YZ’s rivals. If pushed, the lever went away rapidly, and most routine clutch hammerers benefited from an aftermarket improve. Except for the clutch, nonetheless, the brand new motor proved completely bulletproof with glorious efficiency and trouble-free operation. The metal bars weren’t notably strong, however this was par for the course in 1999. On the time, solely KTM provided premium-quality alloy bars as inventory tools. The brand new Takasago Excel rims had been extremely sturdy, and the identical high-quality elements had been utilized by the manufacturing unit groups. The brand new rear hub additionally featured a Honda-style bolt sample, so any spare CR sprockets bolted proper up. The YZ brakes labored very effectively, however its sophisticated Akebono entrance grasp cylinder made lever changes a little bit of a ache.

In 1999, Yamaha launched the machine that will dominate 250 racing into the brand new Millennium. Twenty-five years later, the fundamental DNA of the ’99 YZ250 can nonetheless be seen in Yamaha’s surprisingly aggressive two-stroke machine. Photograph Credit score: Yamaha

Total, the 1999 Yamaha YZ250 proved to be a stable enchancment in efficiency and probably the greatest 250s of 1999. Its new motor was broad, versatile, and quick, whereas its chassis offered the dealing with to place it on the entrance. Its suspension required a little bit of fine-tuning, however when you dialed it in you had a motorbike able to successful on any monitor and at any degree. At the moment, the YZ250 lives on with the identical primary engine that debuted in 1999 and it stays aggressive towards far newer and extra technologically superior rivals. In 1999, Yamaha launched the machine that will dominate the 250 class for many of the 2000s. Its mixture of dealing with prowess and motor efficiency was almost unbeatable till the four-strokes took the highlight away from the oil burners for good. One of many final nice two-stroke designs, the 1999 YZ250 is a machine that has stood the check of time.



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