Yamaha XJ 700X Maxim
Yamaha XJ 700X Maxim
Air cooled, four stroke, transverse four cylinder,
DOHC, 5 valves per cylinder.
Bore x Stroke
68.0 x 48.0 mm
4x Standard side-draft 33 mm Mikuni CV
CDI / electric
64.1 kW 86 hp @ 9500 rpm
6.90 kgf-m 49.9 ft·lb @ 8000 rpm
5 Speed / shaft drive
1st 35/16 (2.187) 2nd 30/20
(1.500) 3rd 30/26 (1.153) 4th 28/30 (0.933) 5th
38mm Telescopic fork, Air, coil spring, oil
damper, 150 mm 5.9 in wheel travel.
Swing arm Coil spring, oil damper, 99 mm 3.9 in
760 mm / 29.9 in
224 kg / 511 lb
You know the policy book on
cruisers: celebrations of form. Function missed the party or never got an
invitation. Now Yamaha rolls out its new five-valve Maxim-X, and this bike says
form and function can unite Peacefully in Coexistence. Make that
Sporting purists beware. It is no
longer possible to soft-pedal cruisers as mechanized cosmetology, two-wheeled
pompadours as debased of functional integrity as they are possessed of garish
filigree. Yamaha's new XJ700 Maxim may sparkle with ornamentation and shimmer
with stylish curves, but don't let its luminosity blind you. As a cruiser, it is
extraordinary in its ergonomic sensibility and functional leanings, exceptional
in its speed and acceleration. The new Maxim's five-valve, liquid-cooled engine
delivers performance that absolutely flattens anything in its class and makes it
as hot as any sporting 750 ever, save Yamaha's own five-valve FZ750.
The Maxim-X lays to ruin the
dichotomy of style and function: More significant even than its 20-valve
technology and high-performance numbers is its demonstration that trendy fashion
need not preclude comfort and versatility and that power and high-style need not
be at odds. With the Maxim-X, Yamaha has rounded the corner and headed back with
function as the central issue, back to the virtues of solid engineering that
remain long after the glitter has lost its sheen.
What's more, the Maxim provides
an engineering perspective of cruiser evolution. Yamaha's original Maxim,
introduced four years ago, marked the end of cruiser adaptations - the practice
of bolting high bars and low seats to existing standard models - and the
beginning of Japanese cruiser engineering from the ground up. The resulting 650
Maxim emerged as a huge marketing success even though it manifested distinct
handling disabilities and set new lows in spatial deprivation. The 650 was a
novelty - a bit of style in a single pictorial flash - but its 12-second engine
screamed motion loud and clear.
Four years later we have the
Maxim-X, more stylized and in every way a more accomplished piece than the
first-generation Maxim. Five-valve trickery aside, Yamaha trumpets no
breakthrough technology in bringing about this metamorphosis, a quick scan of
the essentials reveals precious little change from the original
article-twin-shock rear suspension, leading-axle fork, full-cradle frame,
stepped seat, and a shaft final-drive, crankcases and cylinder block that remain
unchanged. So where are the big improvements in the Maxim?
In truth, Yamaha engineers have
made drastic changes, visually subtle yet significantly effective. In choosing
to improve the Maxim while preserving the traditional cruiser look, Yamaha
encountered the single most difficult problem for anyone who makes such an
attempt. How do you maintain a profitable silhouette when the components most in
need of change are the very ones that dominate the picture? (Could Dolly Parton
become an effective sprinter without losing something along the way?) Sweeping
handlebars cramp the riding positions, stretched front ends tend to flex, and
low seats impose severe limitations in wheel travel. Cruiser engineers concerned
with ride quality, cornering ability, stability and general comfort face
formidable and unique problems.
Look at the new Maxim's handlebar
and see the previous buckhorns wrestled into a more sensible shape: lower,
flatter, angled to position the rider's palms down: look at the seat and see a
more comfortable perch that places a rider even closer to the ground - look at
the footpegs and see them moved forward and down to provide more leg room.
Simple enough, but what you don't see are the complex chassis alterations
fundamental to the Maxim's reshaping. Yamaha engineered an entirely new frame
for the X, one that plays visual tricks with the front end. The steering head is
located considerably higher than the old Maxim's to offset the lower handlebar.
Since the fork is much longer than the 650's, Yamaha increased the diameter of
the stanchion tubes from 36mm to 38mm and linked them with an aluminum fork
brace. In addition, the front end kicks out two and a half degrees farther, up
from the 650's 29-degree rake figure, and trail has dropped four millimeters. To
regain any steering agility lost in the additional rake, new aluminum triple
clamps carry the fork with less offset.
Given the additional fork length,
Yamaha was able to increase wheel travel to 5.9 inches, up from 4.7. The extra
travel also provides more latitude in suspension calibration: spring rates up
front are lighter than before, and rebound damping is slightly increased. To
keep the lighter coil springs from bottoming, Yamaha has provided a single
air-valve which links and balances pressure in both fork tubes and makes
Yamaha engineers also worked
style-engineering tricks on the rear. The tail section of the frame is lower,
bringing the seat height down, and the dual rear dampers are canted forward.
Though shock travel dropped 10mm, wheel travel is up three millimeters. We
suspect this change in shock position has more to do with styling than
rear-suspension performance; we also suspect the improvement in ride quality is
a reflection of more sophisticated damping components and knowledge gained in
coordinating spring and damping rates.
Yamaha first sought to control
heavy shaft-drive components in limited travel suspension systems with heavy
compression damping, light rebound damping and light springs: In the original
Maxim, the result was an alternately squishy and harsh ride with enough
shaft-induced spasms to initiate high-speed wobbles. In the XJ700X, Yamaha has
moved away from heavy compression damping, relying instead on heavier spring and
rebound damping rates to control the shaft. The XJ700X's rear suspension is far
more responsive than the old 650's - more linear, plusher, and more effective at
muting the shaft drive's up-and-down antics. Yamaha's stylists made the job of
recalibrating the rear suspension more complicated by fitting the Maxim with a
heavier rear wheel. The 16-inch cast aluminum hoop is solid but for five narrow
slots and carries in its hub a drum brake. Tire size and rim width are identical
to the old 650's and put a good deal of rubber on the ground. Up front, we see
function gaining clear advantage - in place of the 650's narrow 1.85-inch wheel
is a cast aluminum five spoke, 2.15-inch unit which wears a correspondingly
wider tire. With a bigger footprint up front, the Maxim rider can now take
advantage of the XJ's additional front disc brake.
Powerful and linear, the dual
front brakes do an admirable job of stopping the Maxim but we'd prefer less
lever travel. Coupled with a long travel throttle mechanism, the high-effort
brake can swell your forearm quickly doing swift backroad work. It is precisely
here - on snaky, torturous rovery, that the Maxim divorces itself from the
traditional cruiser crowd. While the Maxim may be visually linked to its back
contemporaries, its handling cues enable it to keep more sporting company. Its
accommodating ergonomics, suspension balance, grippy and ample cornering
clearance puts it in the same handling league as Honda's snappy Nighthawk S.
Despite gaining some 40 pounds
(but weighing in only 1.5 pounds heavier than the Nighthawk) 2.5 inches of
wheelbase over the first Maxim, the five-valve X-model displays superior
equilibrium and broader handling capabilities than the original. Though a good
deal of driveline lash is apparent in the lower gears, shaft effect is less
pronounced than anything we've sampled from Yamaha. With rear shock preload set
on the number four of five positions, shaft induced rise and fall is minimal.
Cushier during urban trolling and freeway riding at the lower settings, rear
suspension action at the upper settings translates to a firm ride.
Attribute much of the Maxim's
comfort to its excellent seat. Wide, well padded and properly dished, the
Maxim's saddle provides room to move about, support for the rider's thighs and a
good measure of isolation from jolts that sneak past the rear suspension. Sharp
bumps taken at speed would spike the rider's tailbone with a lesser seat or a
bolt-upright riding position, but the Maxim's plush perch and subtly aggressive
seating arrangement ensure unchecked jolts are dissipated.
The front suspension needs only
air resistance from 10-17 psi to perform its many tasks. Set up softly, the fork
is plush and responsive but prone to dive excessively during hard braking. Even
when the fork was set at higher pressures, some of our testers felt the need for
an anti-dive system. Keep in mind, however, this need arose only when the Maxim
was ridden well beyond the limits of the average cruiser. At these high speeds,
the fork provides the Maxim's only serious weakness. Cornering at a truly
sporting pace can cause the fork to flex, particularly on a ripply surface.
While the fork brace prevents torsional movement, it provides little resistance
to the fore and aft flexing that robs responsiveness in so many stretched
cruiser front ends.
Other manufacturers have solved
this problem with larger-diameter fork tubes and by increasing the distance
between triple clamps to provide more support. Yamaha instead fitted the Maxim
with a gull-wing-shaped lower clamp that increases the unsupported length of the
stanchions. This arrangement has traded style for function and is not in keeping
with the Maxim's new character.
Nevertheless, the Maxim-X has
elevated cruiser form to new functional heights. It is beyond doubt, the most
athletic cruiser we've ridden. This is progress. Yamaha's cruiser chassis
engineers, at one time two steps behind the stylists and engine designers, have
caught up in a single forward leap and freed the stylists and engine designers
to proceed unshackled.
Yamaha's approach to building the
XJ700 engine was simple and direct. Four years ago, engineers designed a
compact, in-line four to power the original Maxim. By moving the alternator from
its standard crank-end placement to a gear-driven jack shaft behind the cylinder
block, Yamaha could give this plain-bearing engine wide bore centers within
narrow overall dimensions. Through several bore and stroke variations this same
bottom end and drive shaft unit have proven a rugged foundation for eight
different Yamaha models - ranging in displacement from 650 to 900cc - including
The X distinguishes itself from
this group by being the quickest incarnation yet. Yamaha's XJ900 Seca - a rocket
just two years ago - posted an 11.82-second quarter mile, our Maxim ran a
scalding 11.79-second quarter at 112.82 mph. Furthermore, its 0-60 acceleration
is closer to Kawasaki's potent 900 Ninja than to anything in its own class. Its
top-gear roll-on figures from 45-70 mph place it deep into big-bike territory
and prove that the Maxim-X doesn't sacrifice mid-range for blinding top-end. If
this broad-range muscle is five-valve technology speaking, we like what we hear.
Not coincidentally does Yamaha's
five-valve FZ750 sport bike share cylinder bore and bore-center dimensions with
the Maxim-X even though the FZ's lower end is completely new. Yamaha had a
fire-breather Maxim in mind when the FZ was on the drawing board, and by sharing
dimensions the Maxim could also borrow from the FZ's parts bin. Both bikes use
common valve gear, liquid-cooled cylinder block and, upper cylinder head
castings. Though the bore centers were wide enough to accommodate liquid
cooling, there was not enough material between bores to provide the needed
structural strength with wet liners. Both the Maxim and FZ use semi-wet liners -
a sandwich arrangement with dry liners top and bottom and liquid flowing against
the iron liners in the center and up through water jackets to the cylinder head.
This central section is positioned within the cylinder block so the piston
always strokes within the wet liner where heat dissipation is most crucial.
Sliding the Maxim under the ITC
tariff wall was a matter of clipping the FZ's 51.6mm stroke down to 48.0mm, one
of the shortest stroke dimensions in all of motorcycling. With the same
top-to-bottom cylinder-block height as the FZ and a shorter stroke, new pistons
had to be made to bring the Maxim's compression ratio back up to FZ-spec 11:1.
These pistons are longer from wristpin to crown than the FZ's, and we suspect
the weight of their additional material is partially responsible for the Maxim's
lower redline - 10,000 compared to the FZ's 11,000 rpm.
After much deliberation over
valve configuration (see Cycle, March 1985, for the FZ750 Tech Analysis)
Yamaha engineers arrived at five valves per cylinder because it produced the
greatest benefits with the least complication. Which is not to say the system is
simple or a snap to adjust. Placing 20 valves and 20 cam lobes in a space
previously occupied by only eight is bound to complicate valve adjustment.
As in the FJ1100, Yamaha chose
direct valve actuation for the Maxim's five valve system. Each cam lobe rides
against a cylindrical, flat-topped follower. Adjusting shims, located between
the valve stems and the followers, can only be changed with the camshafts
removed. While this system is no doubt more trouble to adjust than a rocker-arm
setup with screw-and-locknut adjusters or a shim-over-bucket system, there are
no rocker-arms to flex and no possibility of shim spitting at high rpm. To
extend valve adjustment intervals, Yamaha used top-shelf valve components. Valve
seats are sintered copper iron, and the hollow chrome-moly camshaft lobes have
carburized surfaces - a treatment normally intended to decrease wear in heavily
stressed gears. In addition, each of the Maxim's valves are small and light,
requiring only a single, light-gauge spring for valve control.
Aside from increasing
displacement, the four-stroke engine builder must use innovative methods to gain
horsepower: raising the engine's rpm and improving the combustion chambers'
ability to burn fuel quickly and efficiently then become the goals. Using five
valves - three 21mm intakes and two 23mm exhausts - the Yamaha system offers
advantages in both areas. The Maxim's five valves yield increased valve
perimeter compared to a four-valve system: This allows shorter cam timing, which
means the piston requires almost no valve relief. The large cylinder bore and
small valves allow the use of narrow valve angles and a shallow combustion
chamber, which makes high-compression possible without domed pistons. In fact,
both the Maxim and FZ use dished pistons to form what Yamaha calls a
"lens-shaped" combustion chamber. This bi-convex chamber offers unobstructed
flame travel and a high concentration of charge near the centrally located plug.
By clearing the combustion chamber of obstructions, fuel can burn faster and
more efficiently, allowing the Maxim engine to tolerate a high-compression ratio
without the threat of destructive detonation.
To make room for all that valve
gear, Yamaha designed the Maxim's cylinder head in three tiers: the lower
portion contains the combustion chambers, ports and valves; the second storey
houses tappet guide bores, camshaft webbing and support bearings. A magnesium
valve cover serves as a roof for the structure. The Maxim's lower half differs
from the FZ750 because the FZ's cylinder block is angled forward at 45 degrees
to facilitate straight ports and downdraft carbs. By utilizing the existing 650
crankcases, the Maxim's cylinder heads are locked in at a 14 degree forward
cant, straight ports with such a head at this angle would put the carburetors
somewhere around your belt buckle. A new lower tier was cast to accommodate the
Maxim-X's downward port deviations and four standard sidedraft 33mm Mikuni CV
With the Maxim's five valve
system, Yamaha engineers have managed to thumb their noses in about five
different directions. Not only does the Maxim make startling mid-range in a
power curve that leads with few bumps to an astonishing top end poke, it does so
with flawless carburation that sips instead of gulps. Extended deep throttle
sessions dropped mileage to only 39 mpg. Leisurely highway riding delivered 51
miles for every gallon that passed over the Maxim's pallette.
Frugalities aside, the Maxim's
engine is a smooth piece - no fuss cold starting manners, slick, crisp, well
matched gearbox, sturdy clutch, no annoying vibration. At 55-65 mph, some
vibration passes through the engine's rubber mounts, but it is a muted roughness
with no sharp edges. Down low, the X is aggressive enough to let you zip past
freeway traffic without touching the shift lever, but at 7500 rpm an impressive
disappearing act occurs. The X kicks so hard above seven five its midrange feels
wimpy by comparison. From 7500, it will rev quickly past its 10000 rpm redline -
quickly enough to lighten its front end exiting corners and trigger its 12000
rpm electronic rev limiter if you're not careful. Those who aren't careful may
find reason to be - the Maxim continues to make serious power deep into the red
zone and will pull to redline in top gear at 129mph.
The Maxim X is a motorcycle that
doomsayers claimed would never be built. Traditional cruisers have function all
right, it's a function of style. In the Maxim-X, we see stylized function - a
different matter altogether. The suspension still has some weaknesses and it is
here that cruiser engineers must concentrate future efforts. Still, the Maxim's
broad range is impressive. It is capable of out gunning anything in its class,
while also being genuinely comfortable, nimble around town, and a willing and
able backroad accomplice. At a time when all motorcycles are more specialized
and yesterday's do all standard is history, Yamaha has created a balanced,
versatile machine that imposes few limitations, a machine that could easily
become the standard of tomorrow.
Source Cycle Magazine 1985