GP’s Classic Steel #70: 1984 Yamaha YZ250L

For this week’s GP’s Classic Steel we are going to take a look back at the machine that took Ricky Johnson to his first National Motocross title, the 1984 Yamaha YZ250L.

For this week’s GP’s Classic Steel we are going to take a look back at the machine that took Ricky Johnson to his first National Motocross title, the 1984 Yamaha YZ250L.

While the 1984 YZ250 looked to be little more than a warmed over ’83 model, it was actually a majorly revamped machine. Careful refinements and a major injection of horsepower made it one of the most competitive machines of ’84.

The early eighties was an era of the have’s and have-nots in the world of motocross. At the top of the pecking order was Factory Honda, with their $100,000+ works specials and limitless resources. On the bottom wrung was Yamaha, hamstrung by financial woes and sub-par production machines. By 1984, this dichotomy between the rich and poor came to a head with Yamaha’s decision to campaign production machines for the ’84 season. This meant that Broc Glover and Rick Johnson would be stuck campaigning little more than privateer YZ250’s against the likes of David Bailey and Johnny O’Mara on their mega-bucks RC250’s. It was truly a case of David vs. Goliath for motocross supremacy.  

 

Luscious vibes: From the low-end to the midrange, nothing could touch the Yamaha in ’84. It barked off the line and ripped through a vicious midrange surge, before running out of steam on the top-end. Only a recalcitrant transmission held it back from being the best motocross motor of ’84.

Amazingly, in 1984, the little guy actually won. In spite of riding a basically stock YZ250, Yamaha’s Rick Johnson captured the 1984 250 National Motocross title over a field of full-works Suzuki’s, Honda’s and Kawasaki’s. Yamaha had claimed that their stock bikes were good enough to win against everyone else’s Factory bikes, and for once; it seemed to be more than just a bunch of hyperbole. So was this a case of superior talent and will overcoming an inferior machine, or was the ’84 YZ250 just that good?

In truth, the answer is certainly more of the former than the latter, but the YZ250 was certainly part of that success. So what was the key to Yamaha being able to run with the big boys in ’84? One word: horsepower.

 

Man over machine: There can be little doubt that Ricky Johnson brought a knife to a gunfight in ’84. Pitted against Ron “The Machine” Lechien and his $100,000+ works Honda RC250, RJ waged a season long battle on his lowly “production” YZ250. Equipped with little more than an Ohlins shock, a front disc and a Simmons Anti-Cavitation kit in his forks, the Bad Boy overcame the might of Team Honda to claim the 1984 250 National Motocross title.

In 1982, Yamaha had unveiled an all-new YZ250 to the motocross press that packed every buzz word available into one package. It was a liquid-cooled, power-valved, mono-shocked motocross weapon, which…turned out to be an utter disappointment. It was overweight, underpowered, ill handling and unreliable. While it looked impressive on the spec sheet, on the track, it was an unmitigated disaster.

 

After many YZ’s suffered frame failures in ‘83, Yamaha beefed up the steering head and added a two-piece head stay to the ’84 YZ. In addition to the added bracing, the motor was moved down and forward to shift additional weight to the front end. The result was one best handling packages of ’84.

Enter 1983, and Yamaha once again introduces an all-new YZ250. The new bike is a clean sheet design and shares only a passing resemblance to its unloved predecessor. It is much improved with a punchy, powerful motor and greatly improved handling. Reliability is a bit of an issue, as frames prove prone to breakage and there are numerous problems with the water pump and its seals, but overall it is a huge step in the right direction.

 

Classic: I still love these retro bike ads.

Which brings us to 1984, and the third all-new YZ250 in just as many years (Can you imagine Yamaha doing this today?). For ’84, Yamaha once again went back to the drawing board to come up with a bike that could unseat the mighty Honda CR250R. Nearly everything, including the forks, shock, rear lever ratio, tank, seat, pipe, ignition, porting, wheels, grips, transmission, airbox, silencer, water pump, side plastic and drive chain, was changed on the new YZ. While it once again may have looked like the same old Yamahdog, this was actually a whole new breed of Y-Zed.

 

With a scooped out saddle and tall, bulky tank, moving forward and aft on the YZ was no easy task. When it came to ergonomics, no one came close to Honda in ’84.

Without a doubt, the star of the ’84 YZ package was its awesome motor. For ‘84, Yamaha took a hard look at their YPVS (Yamaha Power Valve System) mill and agreed that they needed to find a way to get more ponies out of its 246cc’s if it was going to have a prayer of hanging with the Honda’s. In ’83, The YZ had produced a strong hit, but no breadth. It was fast, but hard to use and difficult to keep on the pipe. With the new mill, Yamaha hoped to keep the strong midrange blast, but mate it to a wider spread and easier-to-manage delivery.

Broc Glover would struggle indoors on the YZ in ’84. His best finish of the year would be a second at Pasadena, finishing out the season in seventh overall. He would fare better outdoors on the YZ490, winning two events and finishing second in the final standings.

In order to accomplish this, Yamaha added a new three-port exhaust, reconfigured the intake boost ports, redesigned the reed-valve and recalibrated the YVPS to open later. They also spec’d a new piston, pipe and enlarged the airbox in hopes of broadening the power. In order to better complement the new powerband, a new transmission was also added with closer ratio’s for third, fourth and fifth gear. 

For ’84, Yamaha made several changes to their 246cc YPVS  (Yamaha Power Valve System) mill. A new three-port exhaust, reconfigured the intake boost ports and a redesigned reed-valve all helped broaden its previously narrow spread of power.

The result of all this hard work was one of the best power packages on the track in ’84. The YZ barked from the first crack of the throttle with a meaty surge of low-end torque that hooked up and positively blasted the bike out of tight corners. After it’s burly low-end surge, the Y-Zed climbed into its patented mid-range explosion, before falling off as the revs neared redline. It was the kind of brawny power that craved deep loam and ripped holeshots. On really fast circuits, its lack of top-end pull was a handicap, but on most courses, its impressive “right now” delivery gave it an advantage.

Return to sender: Yamaha tried to literally reinvent the wheel in ’84, to disastrous results. Their new “Z-spoke” wheel design employed a single long spoke (instead of two short ones) that ran through small tabs in the hub from one side of the rim to the other.  Unfortunately for Yamaha, the new design placed fantastic loads on the small hub brackets, breaking them at alarming rates. This “bright idea” would only last one year.

As with any Yamaha of this era, the biggest issue with its motor was its recalcitrant transmission. In short, the YZ was nearly impossible to shift under a load. Catching that second to third shift on a tricky jump face was like playing Russian Roulette on the stubborn Yamaha. The only thing helping matters was the Yammi’s powerband, which could be short shifted and easily pull the next gear. By doing this, a rider could hopefully avoid that tricky shift all together. Overall, the YZ gave up a good bit of top-end power to the blazing-fast Honda, but made up for it with its lighting fast response and meaty midrange power.

Grim: By far the biggest handclap on the ’84 YZ’s, were its pathetic forks. The 43mm KYB’s were so under sprung and under damped, that they were nearly unridable in stock condition. Even with a set of stiffer springs, these were the worst forks in motocross.

After the frame breakage issues of ’83, Yamaha focused a great deal of its R&D efforts on the chassis for ’84. The new frame was both stronger and better handling than the ’83, by beefing up the weak areas that need attention (steering head, head stay) and reconfiguring the engine cradle to place more weight on the front end to aid cornering. Also aiding the new YZ was an off-season diet plan that yielded a five-pound loss over ’83. This put the YZ at a svelte 216 pounds and made it by far the lightest bike in the class.

 

Yamah-hopper:  The Mono Cross rear suspension on the YZ offered a huge range of adjustments, but mediocre performance. Overly light on rebound damping, it was notorious for kicking up on sharp hits and while under braking.

With its lightweight chassis, redistributed weight bias and excellent engine response, the YZ actually handled for the first time in years. Gone was the floppy front-end feel and vague steering response; replaced with a solid feel and sharp turning. While the new YZ was not quite as agile in the turns as the scalpel sharp Honda, it was light years better than previous Yamaha efforts. On the plus side, the YZ also was far more stable than the Honda at speed. Headshake was minimal and the bike felt light whether on the ground or in the air. While somewhat pudgy in the middle and bulbous at the tank, most riders could live with the layout. Overall, the YZ rated a “very good” in the chassis department. It was by far the best handling YZ in nearly a decade and certainly good enough to keep the YZ in the hunt.

After several years of clankers, Yamaha finally hit the mark on the new Y-Zed. A new frame and snappy motor made changing direction a breeze in ‘84. Mike “Too Tall” Bell demonstrates.

Where things went wrong for the YZ was in the suspension department. For ’84, Yamaha spec’d out a set of 43mm front forks that looked to be as up-to-date as anything in the class. Newly added, was the ability to adjust compression damping remotely with the use of a small screw threaded to the bottom of the fork tubes. This was a bit overdue, as many of the YZ competitors already offered this feature, but it was a nice addition nonetheless.

While the forks looked up-to-date, their performance left a lot to be desired. They were badly undersprung and underdamped for anything more aggressive than trail riding. At even a moderate pace, they would bottom with a wrist jarring metal-to-metal (token Scott Sheak reference) clank. Damping was likewise, too light to properly control the action of the forks and adding stiffer springs only compounded the overly light rebound. Jump, clank, pogo, repeat, best described the YZ’s fork action. While none of the Japanese 250’s had what could be called “good” forks in ’84, the gruesome KYB’s on the Yamaha were the worst of a mediocre field.

 

Unfair advantage: While Ricky Johnson and Broc Glover were racing glorified stockers in ’84, Team Honda riders got to race rolling pieces of moto- exotica like this RC250 ridden by David Bailey. These one-off works specials shared not a single part with an off-the-shelf CR and cost upwards of twenty times the price of a production machine.

In the rear, the YZ faired a little better with a supremely adjustable Monocross setup. The Kayaba shock on the YZ offered compression and rebound damping as well as an adjustment for preload. This allowed a dizzying amount of possible combinations; all of which were no match for the performance of the Full-Floater Suzuki. Spring rates were in the ballpark, but just as in the forks, damping was too light for proper control, particularly on rebound. In short, Yama-hop was alive and well in ’84!

 

While the stock YZ was a pretty good bike, there is no doubt the talent and determination of riders like Rick Johnson made it look a lot better than it really was.

In the details department, the ’84 YZ took some gambles in ’84. Some that paid off and some didn’t. One of the first bikes to offer a “safety seat”, the YZ’s up-the-tank saddle was praised for safety, but panned for comfort. With its large, somewhat bulbous tank and low, scooped out seating position, sliding for and aft was far more difficult on the YZ than on the other machines. Seat reliability was also suspect, as the mounts tended to pull loose of the tank and the foam was notorious for splitting in the middle.

Another area of great concern for ’84 were the YZ’s innovative “Z” spoke wheels. In ’84, Yamaha had the bright idea to use one long spoke that ran from one side of the rim to the other, instead of two short spokes to lace the wheels. There was a kink in the middle of each spoke that ran thorough the hub, which accounted for its unique name. The problem with this innovative design was reliability, as the Z-spokes placed far too much stress on the small tabs that attached them to the hub. Broken wheels were the order of the day and any pro worth his salt went aftermarket in ’84.

 

Brake it to me: By 1984, Yamaha’s excellent dual-leading shoe brakes were beginning to look a bit like a moldy oldie. Amazingly, and in spite of disc brakes on the Honda and Kawasaki, both MXA and Dirt Bike picked the Yamaha as having the best overall brake package of ’84.

One gamble that did pay off in ’84 was Yamaha’s decision to stick with drums for ’84. Incredibly, and in spite of front discs on the Honda and Kawasaki, the YZ was picked to have the best overall brakes in the class. The Yamaha’s dual leading shoe drum front binder was praised for having far better feel than the grabby and wooden KX disc and offered nearly as much outright power. While the Honda front disc offered more bite, its chattery and short lived rear drum was panned by all. When you combined the front and rear, the YZ’s drums were chosen as the best overall package. Strange, but true- my how times have changed.

 

At $2429, the ’84 YZ250 looked like a pretty sweet deal for a true to life Factory bike. Of course, for that price you got a set of forks set up for an IT200 enduro bike and an eject-O-matic rear shock. But oh, you did get that sweet motor and a bike that weighed less than some European 125’s. Overall, it was a bike with a lot of potential, but a few details short of greatness.

In 1984, Yamaha made the bold decision to actually race what they sold. This, in an era of ultra-exotic, mega-bucks specials. Amazingly, the bike they produced was good enough to win the 250 National title and nearly good enough to capture the honors of 250 Bike of the Year. It was fast, light, handled well and backed by Yamaha’s extensive “Wrench Reports” technical database. If not for its abysmal forks, it would have be the best bike of ’84. C’est la vie.

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