$1000 Sportbike Surgery
Source: Motorcyclist, January 1996
Supple suspension and burly brakes give Kawasaki's ZX-11 twisty road
manners to match its straight-line speed.
Nine out of ten ZX-11 bull sessions around here begin with celebrating
its 131 horsepower and 175-mph escape velocity. But the tenth invariably
berates the bike's harsh, uncontrolled suspension and fade-prone brakes.
So after five years of waiting for Kawasaki to cure the Maximum Ninja's
afflictions, we set out to doctor them ourselves.
For starters, we wanted enough linear, fade-free stopping power to match
the ZX-11's triple-digit proclivities. Even the grippiest aftermarket
brake pads alone weren't enough. Reining in 601 pounds of Ninja (that's
an 800-pound projectile with a full-size rider on board) generates more
heat than Kawasaki's heat-treated stainless steel rotors can dissipate.
Working against standard sintered-metal pads, hard-core backroad antics
generate enough heat to fade or even warp stock ZX-11 rotors.
To dissipate 175-mph heat more efficiently and generate more consistent
stopping power, we cued up a set of Ferodo ductile iron (that's ductile
as in malleable, as in more likely to bend than crack or break) brake
rotors ($535 including brake pads and hardware).
The rotor swap is reasonably easy if you know a die grinder from a blow dryer.
Still, follow the directions to the letter and triple-check everything.
Extra care now can prevent big trouble the first time you reach for the lever.
If you're not comfortable with the process, have a pro do it.
Grind off the stock rivets to remove the stainless rotors, then mount new
iron "blades" on the standard aluminum carriers using new buttons that
come with the kit. Presto! Race-spec floating rotors. It takes a few miles
for the new pads to chew through the anti-rust zinc plating to bare iron
be neath. Once the swept area shows clean iron, popping the pads out to
scrub off any accumulated zinc (try emery cloth spread over a hard, flat
surface) accelerates the bedding-in process.
Though they're rated to survive 1100 degrees Fahrenheit, Ferodo says the
semi-metallic C.P. 901-compound pads run cooler and are kinder to rotors
than the average sintered-metal equivalent. No worries about "Racing" in
big letters on the package. Ferodo recommends their less aggressive (and
less abrasive) SuperSport-compound pads for streetbikes with stainless steel
rotors. You could use C.P. 901-compound pads with stainless steel rotors.
Still, the ductile iron works much better.
Even so, prepare to be slightly underwhelmed for the first few stops out of
the garage in the morning. Even warm, initial bite is slightly less
immediate than fresh, stock ZX-11 brakes. But from there, the new setup
seems to thrive on heat rather than wilt under it. Spreading impressive power
over a broader band of lever travel, the Ferodo brakes have a more linear
feel than stock, making it much easier to feed in just the right amount of
stopping power in any situation. They're never grabby. And shy of outright
abuse, they don't fade either.
Onward to the suspension ward. The easiest way to make the ZX-11's
alternatively harsh and mushy damper-rod fork behave itself is to slide in
firmer fork springs, followed closely by a set of Race Tech Cartridge Fork
Emulators ($124.95, plus two pints of your favorite 15W fork oil).
With the patient opened up on the table, we traded the flaccid 0.83kg/mm
ZX-11 fork springs for stiffer, straightrate 0.92kg/mm Race Tech units
($89.95). And since each stiffer, straight-rate fork spring is shorter
than the progressive coil it replaces, a steel spacer takes up the slack.
An Emulator transplant is more complex than just swapping springs, but
anyone with reasonable mechanical aptitude, a good set of tools and opposable
thumbs can handle it. Instructions are first-class, as is the installation
video that comes with the kit. But what if you read the instructions, watch
the video, then get everything apart and still panic? Then there's a calm
voice at Race Tech's tech support hotline to talk you down.
On the Eleven, defeating Kawasaki's external rebound damping adjusters
complicates installation a bit. Let somebody else handle the brazing if
you're welding-impaired. Race Tech does the job for $15. Otherwise, if you
can change fork seals, you can probably install the Emulators.
What you get for your time and money is more precise, more adjustable rebound
and compression damping. The Emulator-equipped fork controls rebound damping
with fork oil viscosity; 15W in this case. Meanwhile, varying the Emulator
valve's adjustable spring and bleed hole lets you tune low-, mid- and
high-speed compression damping to taste. The only downside is the lack of
external damping adjustments. You'll have to spin off the fork caps, slide
out the springs and fish out the Emulators to make changes. Adjustments take
about 15 minutes after a little practice.
Heading aft, the main problem is inconsistent damping from a painfully basic
KYB emulsion shock. The air/oil meringue flowing through its stock valving,
you see, is inherently variable, and the design of the stock shock's damper
piston limits the amount of tuning you can do. The net effect: Dreaded
High-Speed Wallow at prime roosting velocity. The fix is another type of
crafty Race Tech valving gear.
Rather than burn the limited budget with a new shock, we tried Race Tech's
40mm Gold Valve Shock Kit with a remote reservoir ($259.95, plus $24.95 for
one quart of shock fluid). To keep the shock body's soft aluminum bore from
wearing away and contaminating the damping fluid, Race Tech hard-anodized
ours ($55) to keep damping consistent over the long haul. From there, one
shock doesn't fit all, so Race Tech sets up each kit according to your bike,
your weight and riding style.
The stock ZX-11 spring was perfect for our 200-pounder. So $340 and some
sweat buys a fully adjustable, rebuildable, remote reservoir diaphragm
rear shock. Remember, it's shock surgery, not brain surgery. Between
the instructions, the video and tech support line, it's actually a little
easier than our fork work. Once the shock is buttoned up, you'll need a
source of high-pressure nitrogen (200 psi) to charge the reservoir, as well
as a pressure gauge capable of adjusting small-capacity/high-pressure
settings. If you're still queasy about the whole thing, Race Tech will
install the kit for another $85.
OK, wash your hands. It's time for a little fine-tuning. We set sag at
37mm up front and 33mm in the rear; a little firmer so the chassis stays
balanced as it squats under power. (See our July '95 issue, p. 70 for the
full rundown on setting sag.) Our Secret Suspension Test Loop told us
baseline damping settings were better suited to a smooth racetrack than
public pavement. Thus we factored some compression and rebound damping out
of the shock valving for more compliance at street speeds, setting the
compression damping 15 clicks out and rebound at the second of four positions.
Up front, we reduced preload in the standard 64-pound Emulator springs from
four turns to one-half turn.
At that rate, the ride is taut, but comfortable. On surface streets, all
but the nastiest craters are effectively erased, as are most freeway
expansion joints. That controlled, compliant feel continues through the
twisty bits. Cranked over in a fast, bumpy corner, the Emulator-equipped
fork impersonates pricey aftermarket cartridge forks, tracking an appointed
line that would have the stocker chattering and threatening to run wide.
Sharp-edged bumps are no longer fed straight into the chassis, boosting
Add accurate damping from the re-valved shock, and the Maximum Ninja is
dead-stable carrying large speed through long sweepers. No more wallowing,
grasshopper. just more comfort, more compliance and more front-end feedback,
even at full-tilt lean angles.
So where does that leave us? Those of you obsessed with such things have
already figured we blew our budget by $100. So we won't tell you about the
extra $320 we spent on new D205 Dunlop Sportmax Touring radials that stick
famously and hardly look worn at all after 2200 miles of hammering. These
are great skins.
We'll say this much, though. It doesn't matter where you ride or how quickly.
Suspension and brakes worthy of The Engine make that 99.9 percent of the time
you can't pull the 175-mph trigger almost as much fun as the 0.1 percent when
you can. Almost. And that, boys and girls, is a certified bargain. Even if
we blew an extra C-note or so to do it.
Quadrant ZX-11 Street Shock
We were looking for another solid, sub-$400 shock to test in this Surgery
deal when thunk!-an EMC Dynamics' Quadrant ZX-1 I shock tumbled out of the
mail bag. Okay, then.
The British Bolt-On Alternative
On paper, the Quadrant looked interesting enough. Though it uses a less
pricey steel body rather than aluminium (steel is notas adept at dissipating
heat), the Quadrant is fully rebuildable and, according to Quadrant, fully
adjustable. Rebound and compression adjustments, which work through a single
knob, are integrated through the use of a twin-tube internal damping
apparatus similar to that of a cartridge fork's internals.
There's also, says Quadrant, an internal "gas cell" for (theoretically) more
consistent damping. And priced at $395 including spring, the price was
Once mounted on the bike (a 1.5-hour job on the ZX-11, notincluding bad words
and throwing things), we set spring preload via the Quadrant's threaded
adjuster (which is almost inaccessible on the ZX). At least the
rebound/compression adjuster's large knurled knob is readily accessible,
allowing roadside damping changes sans tools. But no detents through the
5-turn adjustment range and no marks on the knob itself make precise changes
The standard spring rate (Quadrant offers various alternatives) is aimed at
riders between 143 and 209 pounds -right in the ballpark for most of us.
Once adjusted to taste (we prefer 25 to 35mm of sag), the Quadrant delivers
a controlled, well-damped ride that's more comfortable and compliant than the
stock ZX-11 shock.
But stuck between 601 pounds of ultra-quick Ninja and a few hours worth of
rough tarmac, the Quadrant's damping still fades enough to let the rear of
the bike move around more than we'd like. The single adjuster had marked
effect on rebound damping, but did little to alter the compression side.
It's not quite a match for our more sophisticated Race Tech conversion in
terms of pure performance. However, the Quadrant does offer more control
and a better ride than the stock ZX-11 unit as well as many original-
equipment shocks-at a reasonable price. For those with some extra cash to
spend, Quadrant also offers a higher-performance, remote-reservoir race
shock for $595. But if you're looking to upgrade the average sportbike's
rear suspension without evacuating your wallet, the Quadrant is a viable