700/750 Maxim-X Menu

Cycle Guide  Magazine, May 1985

Although this article refers specifically to the Yamaha 700 Maxim-X Model XJ700X, it applies equally to the 750 Maxim-X Model XJ750X. The two models were identical in every respect except for engine displacement and related performance. While tariffs limited the sale of Maxim-X's to 700cc in the United States, Canada and other countries received the 750cc counterpart in the form of the XJ750X. No question, Canadians (and others) enjoyed Maxim-X performance in excess of that touted in this article.



Road Test: YAMAHA XJ700X Maxim
Slick, smooth and the quickest disappearing act in the 700 class.

Motorcycling has its own magic act these days, with daily shows all over the country and sport-customs as the main attraction. If you don't believe it, then consider: The sport-custom is a blatant contradiction in terms, emphasizing two wildly divergent brands of performance and styling. And combining the two into a single package is a feat that makes turning lead into gold seem like a cinch. But the rewards for success might be worth more than gold; the right sport-custom could command a broader appeal than could a motorcycle from either single category. And that's got the manufacturers putting on pointed hats and waving magic wands, each one trying to build a sport-custom of its own.

Well, Yamaha's wizards have performed their own special sorcery to brew up the XJ700X Maxim[-X], a laser-quick motorcycle that splits the difference between the two seemingly exclusive genres of sport and custom. The Maxim-X doesn't rely on any parlor tricks in its performance, though. Instead, Yamaha invoked a combination of proven and innovative engineering to conjure up this motorcycle, and sprinkled in a chest-full of custom-oriented talismans for good measure, such as a slim, teardrop-shape tank, acres of chrome and a Vmax-style disc/spoke rear wheel.

Those are items that have successfully charmed riders of the custom persuasion before. But Yamaha is counting on the Maxim-X's engine to bewitch performance-minded riders, too, and claims 86 horsepower to help cast the spell. Like most previous incarnations of Maxims, the X's motor is a transverse inline-four with double overhead cams, five-speed gearbox and shaft final drive, with both its starter motor and alternator mounted on top of the cases behind the cylinder block. The X also retains the same shaft centres of Yamaha's 650/750/900 Maxim/Seca engine family, and even the gear ratios for the primary drive, transmission and final drive are the samethroughout. The 700's clutch, too, comes from the XJ900 Seca, which used a strengthened 750 clutch.

Still, it took more than the mere wave of a wand over Yamaha's parts bins to create the Maxim-X's rubber-mounted motor. For instance, the crankshaft and connecting rods are 700-only items, and the cases are new, too. But it's the X's top end that really parts company woth past Maxim/Seca practice. For the 700, Yamaha reached into its hat and pulled out a liquid-cooled, five-valve design similar to that of the FZ750, the firm's new three-quarter liter sportbike. Both engines employ identical bore sizes, valve diameters, valve lift, cam timing and compression ratio.

Moreover, the X enjoys the same benefits from its five-valve setup (three 21mm intakes, two 23mm exhausts) that the FZ does. For example, because the valves are smaller than would be the case with a comparable four-valve design, they're also lighter. Therefore, the engine can both rev higher before valve float sets in, and respond more quickly to throttle inputs. Lighter valves mean lighter springs, too, which decreases seat and camshaft wear while increasing service intervals. Five valves also offer more valve circumference than four - although not necessarily more total intake area - and so expose their area more quickly, which benefits cylinder-filling at low valve lifts. Finally, the five valves are arranged radially, with narrow included angles, making for an exceptionally compact combustion chamber that promotes complete, rapid burning, in turn allowing a high, 11.2:1 compression ratio without detonation.

All the high-tech hardware would amount to so much hocus-pocus if it didn't produce horsepower. And in the Maxim-X's case, it does, making this motorcycle the 700-class top gun in the quarter mile. That's precisely what Yamaha intended, too, and the X ends any arguments to the contary with its scorching 11.779-second/113.63-mph time. What's more, the X smoked off that run on a bad day at the strip, when traction was a now-you-see-it, now-you-don't affair. Overall, that's a phenomenal display of power from an ITC-tariff-shunning 697.3cc engine, and it means the X can put the whammy on anything in its class, sportbikes and all.

Summoning up that performance forced some compromises, though. Yamaha tuned the X motor for high peak horsepower - a necessity for quick quarter-mile times - at the expense of low-end and mid-range power. As a result, the Maxim[-X] requires its pilot to crank hard on the throttle to get to the class-leading acceleration. Yet, despite the tuning, the motor isn't particularly cammy; the power doesn't come in with a bang, as it does with Homda's Nighthawk S, one of the Maxim[-X]'s 700-classmates. Instead, the Yamaha's power gets progressively stronger as the revs climb. Just past 6000 rpm, the X's tuning really starts to work, and you need to watch the tach closely to keep from overrevving the engine, because it will pull straight past its 10-grand redline, effortlessly and smoothly.

That style of power - not to mention the sheer volume of it - showcases the engine's FZ influence, and contributes to the X's ability to storm down backroads. Slick, positive shifting and well-spaced gearbox ratios make it a cinch to keep the motor in its best power range, where it can swoop out of corners in a thrilling, headlong rush. Yet the Maxim[-X}'s power also illustrates the compromises involved in creating a sport-custom. Low-end snap is far more useful for boulevard than the Maxim[-X]'s high-rpm power, and the Yamaha is at a disadvantage to pure cruiserbikes in that respect. Still, many riders will cheerfully accept that deficiency in trade for the 700's brand of fierce acceleration.

In designing the X's chassis, however, Yamaha didn't take such a single-minded approach. For example, the 700's frame, albeit similar to the 750 Maxim's, has a lower seat height and a raked-out 31.5 degree steering head angle (29 degrees for the 750). Yamaha changed the head angle not only to make the front end take on a chopperesque appearance, but to add almost 3 inches to the wheelbase, too, which contributes a long, low look a cruiserbike is expected to have. Conversely, Yamaha wanted the 700's suspension rates biased toward sporting use, and chose new components with stiffer springs and more damping than the 750 Maxim's. But, oddly enough, the 700's shocks adjust only for preload (five settings), whereas the 750 offered both preload and rebound-damping adjustments.

Even without that sport-oriented feature, though, the 700's chassis performs adequately - if not admirably - for frolicking in the canyons. The Maxim[-X] shows a basic willingness to be heeled into corners, and it responds to rider input with surprising ease, needling muscle only in fast esses. Considering the bike's chassis dimensions suggest they were chosen more for style and stability than agility, the steering seems almost supernaturally light. But Yamaha says the credit goes to careful tire selection - not magic.

Unfortunately, Yamaha apparently didn't exercise the same care in selecting the 700's spring and rebound damping rates; both are too soft for aggressive riding or bumpy corners. But for a 160-pound pilot, with standard air pressure in the fork (6 psi; 17 psi is recommended maximum) and shock spring preload set to the fourth or fifth position, the X feels capable and satisfying at an 8/10ths pace on smooth roads. It's when you're really charging that the bike gets unruly. Then the X starts hobby-horsing on its suspension, the tail-heavy weight bias becomes evident and the front wheel's sensitivity to bumps increases.

Hard riding points out some other shortcomings, too, such as the Maxim[-X]'s lack of cornering clearance. The footpegs drag fairly easily, especially if you happen to roll off the throttle in mid-turn. That causes the X to sink on its suspension, providing a pointed reminder that this is a shaft-drive motorcycle, and it wants the power kept on through turns. Fast riding, shaft-style, also means completing your braking before initiating a turn, and with the Maxim[-X] that's even more important. The X's front brake - the same dual opposed-piston calipers and rotors used on the Virago 1000 - takes a heavy squeeze and returns little feel in the bargain.

Still, even with the bike's quirkiness, it would be wrong to say the Maxim-X can't live up to the first part of its sport custom sobriquet. Because, in the right hands, the X can haul down a twisting road almost as quickly as a pure-bred sportbike. A crack sportbike will perform the task for a wider variety of riders, though, and with far less drama.

But sport riding subjects motorcycles to a harsh, unblinking scrutiny, and the Maxim-X regains much of its appeal when viewed as a custom. For example, the X feels far more at home in the city, where you can use the low-effort steering and crisp carburetion to dispatch traffic with ease. And if someone is foolish enough to challenge you on your own turf, just dial on the engine's top-end rush; they'll never know what hit them. Wherever you go, though, the bike's ergonomics feel just right. In fact, the X has one of the best seating positions of any custom bike. Unlike the traditional custom riding position that rocks you back onto the base of your spine and makes you grope for the far-forward pegs, the Maxim[-X]'s low, mildly swept-back handlebar tilts your torso forward only slightly, and finding the footpegs comes naturally, For conjuring up that combination, Yamaha should get a medal.


COMPARATIVE TEST DATA:

Year, Make and
Model
Quarter-Mile
(sec/mph)
Top speed
(mph)
Weight
(lbs.)
Stopping Distance
from 60 mph (ft.)

'85 Yamaha XJ700X Maxim-X
11.779 / 113.63
121
505
135
'85 Susuki GS700E
11.978 / 112.21
125
485
140
'84 Honda Nighthawk S
12.048 / 109.75
125
492
125
'84 Honda VF700F Interceptor
12.323 / 106.50
124
512
136
'83 Honda Nighthawk 650
12.287 / 108.04
122
451
127
'83 Yamaha XJ900 Seca
11.949 / 113.20
128
499
135


No such commendations accompany the Maxim[-X]'s saddle or suspension, though. The saddle is a two-piece, loose-cover affair that's a near-perfect Harley-Davidson copy; it even makes you feel as uncomfortable as an H-D seat does, and in the same short amount of time, too. Fortunately, the Maxim[-X]'s saddle isn't dished too deeply, so you can move around some. But moving around won't help you much in coping with the suspension. We quickly learned to ignore Yamaha's recommended air pressure for the fork (6 psi), instead bleeding it down to 0 psi and getting a great improvement in ride quality. The shocks, on the other hand, start out harsh and stay that way, especially when the rear wheel needs to respond quickly to bumps. The problem stems from excessive compression damping, and the bike flat beats on you over abrupt paving irregularities. So, between the saddle and the rear suspension, you'll be plenty ready to stop when the gas tank goes on reserve - which takes only about 100 miles.

And it's the suspension's shortcomings, more than anything else, thatthwart the Maxim[-X]'s sport-custom alchemy, because the suspension simply isn't up to either task the bike is supposed to take on. Just the same, the suspension isn't the root cause of the X's inability to serve two masters. It's only a symptom of a larger problem, of choosing the wrong set of compromises.

Sportbikes and customs are so far apart in the spectrum of motorcycling that any attempt to fuse the two poses a nearly impossible task; compromises have to be made. The magic, though, is in making the right ones. And Yamaha certainly pulled a couple of good tricks from its sleeves, such as the riding position and that remarkable motor; those things guarantee the bike a broad apeal. Yet, with the right compromises the Maxim-X could have had them all, from the hard-core knee-draggers to the ardent profilers. But to do that, Yamaha's wizards need to try on some more pointed hats, and wave some more wands.

by Charles Everitt - Cycle Guide  Magazine, May 1985