Cycle News is a weekly magazine that covers all aspects of motorcycling including Supercross, Motocross and MotoGP as well as new motorcycles
Issue link: https://magazine.cyclenews.com/i/128400
-
Chris Walker's PSG- 7 Kawasaki ZX- 7OR
L...-
_
neutral-steering and responsive. It would go
where it was told and felt better balanced.
Then I could start to work on keeping up
cornering speed, with the help of the compliant Ohlins fork.
The chassis was also much easier changing
direction from side to side, and for the first
time I could feel how low the weight is carried in the Kawasaki chassis, and how small
and agile the bike is compared to, say, a
Honda CBR I000.
However, I couldn't just hang off and
enjoy the ride, because with the optimum
setup the team had dialed in with a softer
rear-shock setting, I now found I had to consciously stand on the footpegs and lever my
weight forward onto the front wheel exiting
a tum hard on the gas, or else my extra
weight compared to Walker's gave the
Kawasaki a serious attack of the shakes,
which hadn't been the case before. Sensitive
isn't the word - we're not talking kilos of
reduced spring preload here, just grams, yet
it makes such a difference to setup.
Resolving this by weighting the footpegs
gave me problems with Walker's street-pattern gearshift - since I now couldn't get my
toe under the gear lever easily to shift up.
Solution: Use the Kawasaki motor's userfriendly flexibility and flat torque curve to
short-shift with just one green light shOWing
on the dash (around 12,500 rpm, at a guess),
and let it shrug off the fact you're not maxing
out revs without any noticeable complaint.
Magic. At least this meant I no longer arrived
at the end of that front straight at over 185
mph and felt the brake lever come back to
the bar because the pads had knocked back
in the course of the fourth-gear tank-slapper
I'd just lived through over the slight rise just
before the pits. That happened to me on two
different laps before I wised up and realized I
had to move my body weight forvvard.
When Kawasaki first entered MotoGP
racing three years ago, they did so with a
massively proportioned motorcycle based on
their old-generation Superbike that was
unkindly but aptly nicknamed "The
Incredible Hulk." Last season, they turned
that concept on its head with the current
ZX-RR, a compact, low-slung, good-handling
package that leapfrogged Suzuki to put the
green screamie on a rostrum-earning level.
Now Kawasaki has flipped the coin over to
produce a Superbike that's built like its
MotoGP racer - small, stiff, sensitive, and
potentially successful once the PSG-I team
can accumulate the necessary experience
and vital data needed to challenge for top
honors.
That takes time, and testing, and the
budget for both - but my Mugello ride convinced me that with a star like Walker in the
hot seat, Kawasaki is back with a potential
contender for World Superbike success.
Only painted yellow, not green - for the time
being, at least!
eN
Continued from page 39
working on a traction control system, which measures the
To develop the motor, Akira must (under current
differential speeds of the front and rear wheels and
four-cylinder World Superbike rules) retain the
retards the ignition if their difference exceeds a cerrather heavy stock crankshaft but can compensate
tain tolerance, and can cut ignition entirely to
for this on appropriate circuits and in suitable
one cylinder if needed. The system isn't yet
track conditions by fitting a lighter ververy subtle, though - Walker and Sansion of the ramp-style slipper clutch,
chini would still highsitle if they
to reduce flywheel inertia
opened the gas wide open while still
Akira's own titanium rods are fitted
cranked over, as the works Ducati
with ultra-slipper two-ring pistons delivriders are able to do with their Marelering a 15: I compression ratio - Keller
Ii-developed traetion-control syssays they'd like to go higher, but
tem, since the PI equivalent is
then, with the slipper clutch, it
only programmed to wori<
becomes hard to start the
with the big slides.
engine. Akira ports and gasSo while the PSG-I
flows the stock ZX-I OR cylinKawasaki ZX-I OR motor is
der head, then modifIeS the
very much a worl< in
combustion chamber while
progress, Keller is satisfied
retaining the standard titaniwith its potential with less
(Top) Wolker's control •• (Bo"om left) Ohllns provides the rear
um exhaust and steel intake
than one year of developsuspension on Walker's bike. (His teommate uses a Bltubo
valves, each still with a single
ment under its wheels.
rear shock.)
spring.
"We still have a lot to
come from this engine," he
"The new four-cylinder
SBK regulations require you
to maintain the same diameter of valve and valve stem,
as well as the same material
as the stock valves," says
Keller. "It's a handicap with
this motor, as the choice of
material should be the other
way around - titanium inlet
valves at least, or else all titanium. I hope they change
this."
In this form, fitted with
one of the six different cam
profiles Akira has developed
for the ZX-I OR offering
increased lift of up to I.Smm
on both valves, the PSG-I
Kawasaki engine is rev-limitEngine development Is by PSG· 1 's portners In
ed to 13,700 rpm and now
France· Aklra Technologies.
produces peak horsepower
of 20 I hp at the gearbox at
13,000 rpm, with maximum torque at 10,500 rpm, but with a much
says, "but I know Kawasaki has an updated version coming for next
wider spread of power and a softer, smoother delivery.
season, which I hope will see an improved alternator mounted in the
"We've done this by varying the injection map considerably
ColTect position, titanium valves all around, a single top injector, and a
between gear ratios," Keller said. "So the map for fifth gear is quite diflighter crank, which will allow us to play more easily with the engine
ferent to fourth, which is not the same as third - it makes a big differinertia If they do all that, and we can rev it a little higher to just over
ence in controllability and engine response, but takes a lot of time to
I",000 rpm without power tailing off, I know we'll have the basis of a
get just right. We're still wori