Kawasaki KIPS
Kawasaki's KIPS exhaust valve system has gone through a steady
refinement of design. Kawasaki uses a different system to suit the
needs of the different model bikes. The earliest KIPS design used
two drum shaped valves to control the flow of the sub exhaust
ports. Opening the ports gave the exhaust port more time-area. The
main exhaust port was relatively small with modest timing and
duration. A rack and pinion set up controlled the drum valves,
opening them at about 6,000 rpm. Kawasaki uses the rack and pinion
design in all their KIPS systems except the 1998 and later
KX80-125cc models. The 1992 KX125 and KDX used the next generation
KIPS which featured a center wedge valve with two side drum valves
engaged to a rack-and-gear actuating system. This system was very
complicated with all its moving parts. The top and bottom racks had
to be synchronized through the left drum valve, which has two drive
gears molded in it. The drum valves are made of aluminum. When the
drum valve becomes carbon seized, the steel teeth on the rack shear
off the aluminum teeth on the drum valve, rendering the drum valve
inoperable. Check the condition on the gear teeth every time you do
a top-end service, because if one gear fails the whole system runs
out of sync.
On the late model 80-125cc KXs, the KIPS is relatively simple
relying on a wedge valve and flapper. This system is self-scraping
so it requires little maintenance. In the first year of operation
(199
the KIPS system was
plagued with failures like the pin breaking on the flapper, the
valve receding into the cylinder and contacting the piston, and
over-extension of the valve causing cock and jam. In 1999 Kawasaki
changed the wedge valve and flapper design for more rigidity and
that solved all the reliability problems.
However, the drum valves eventually wear at the drive channels for
the center wedge valve, and the sloppy fit between the wedge and
drum valves prevents the center valve from fully opening. That is
why these bikes get noticeably slower as they get older. There is
no preventative cure or aftermarket part. You just need to replace
the drum valves when the drive channels wear out.
1993 was the first year for the KIPS system used through present
day models. The system uses a single wedge and flapper valve for
the main exhaust port and two drum shaped valves for the sub
exhaust ports. The valves are all linked together with two racks
and pinions on the right drum valve and a steel gear on the upper
rack linking the wedge valve. A left-hand-thread nut retains the
gear to the rod that actuates the wedge valve. Check the nut
periodically, if the nut loosens, the wedge valves become
inoperable.
