Carb Basics (pdf)
KZ900 Factory Tune Up Specs
KZ900 Parts Manual
Racing & Performance Tips
Results achieved by these tips are the sole responsibility of
Question on Mikuni carbs ... The standard main jet number
for the kz900 is #110. Kawasaki show in the exploded view, five different main jet
sizes from 110 to 120. I know Vance & Hines Sidewinder recommends installing #130
main jets before installing there 4 into 1 exhaust. I think this just prevents the
pipes from bluing / fine tuning. What's the difference is my question? Does the
main jet size give more fuel to the carbs? The number means how big the hole
is in the jet .. its a measurement ... so yes the bigger the number the more
gas it can flow and yes it helps stops the pipes from bluing, bluing is from the
motor running too lean (not enough gas for the air going through it) lean = hot
very lean = melting pistons the richer it is the cooler it burns until you have
so much fuel in it your not burning it off then you get black smoke out the pipes.
So white smoke would mean a very lean mixture? White like a fog is either
anti-freeze or ATF being burned, nothing else burns white, now there are different
shades of blue.. from a grayish to navy blue.. the richer the blue the fresher the
oil is that's being burned like rings, light blue.. I would say valve seals gray
to black is gas not being burned.
Head GasketsOn motors using 10.5 to 1 compression ratio pistons, a fiber head gasket
will work fine. For racing applications; where 13.5 to 1 compression ratio pistons
are used, a copper head gasket is required. Also, when using a copper gasket, the
cylinder block must be o-ringed to help the copper gasket seal. Cutting a groove
around the sleeve and using a copper wire thickness of .039 is common place. Leave
about .009 height of wire above the block surface.
*A Note Of Caution:
When using fiber head gaskets, put them on dry; no sealers or coatings. For copper
head gaskets, a spraying of copper coat on both sides is sufficient. Allow it to
dry and tack-up for 2 hours before installing. Make sure both the head and cylinder
surfaces have been machined flat and are clean before installing the gaskets.
Do not use a Copper Head Gasket on a water-cooled motor. If the
cylinder has been o-ringed, the gasket will not seal enough by biting into the wire
and the water will leak by causing overheating problems. Use a spring steel head
gasket and do not o-ring the cylinder.
Piston To Valve ClearanceFor those of you with a GSXR 1100, this is the easiest method:
Put a degree wheel on crank, get exhaust at 8 degrees BTDC. Set dial indicator on
valve tip and put screwdriver between the rocker arm and cam. Pull down read indicator
in thousandths to check clearance. With intake set at 8 degrees ATDC, do same as
Ignition SystemFor those of you who plan to purchase the new Dyna-2000 ignition for
a GPZ 1100 motor (1981-85), you must use the ignition housing with seal from a KZ1000J
IgnitionsIf you are having problems with your ignition or rev-limiter check your
ground. Make sure that you are grounding to bare metal, not a painted surface. Dyna
Ignitions, rev-limiters, two steps and Dyna 4000 Ignitions require the use of Dyna
wires to work properly These wires have a wire spiral core center which doesn?t
interfere with the electronics on your bike.
When using a Vance & Hines PowerPak Ignition on your sport bike,
use 3 OHM coils with graphite suppression wires. With a Dyna-2000 Ignition, use
2.2 OHM coils with the same type of wire.
Ignition TimingWhen running a motor at high altitude you must advance the ignition timing.
Example: a Suzuki GS 1100/1150 motor running at 4000 feet above sea level would
advance the ignition timing approximately 3-4 degrees.
Spark Plug GapsWhen running a Suzuki or Kawasaki with a Dyna-S and high performance
coils set plug gap at .026. When running an MSD or Dyna-4000 Ignition system set
plug gap at .018.
Spark PlugsRacing motors usually require a heat range one colder than stock. We
recommend NGK plugs. For a Suzuki GS1100-1150 use a D9EA. For a Kawasaki KZ 900-1000
use a B9ES. With a Dyna-S ignition and aftermarket coils run a gap of .028. If your
vehicle has a MSD box or Dyna 4000 ignition run a plug gap of .018 - .020.
Turbo Engine TimingTurbo bikes under boost create a tremendous intake charge. In order to
release this charge the exhaust must stay open longer than usual. Suzuki and Kawasaki
engines benefit greatly when exhaust cams are set at 112 degrees lobe centers. Set
ignition timing at 28 degrees.
Nitrous OxideWhen running NOS on your bike use a gasoline with an octane rating of
116-120. The higher the octane the slower the fuel burns. This allows you to run
a high compression without fear of pre-ignition and detonation. The higher the compression
the smaller you go on NOS and gas jet sizes. If you have a low compression motor
the bigger you can go on NOS and gas jet sizes. Ignition timing must be set at 28?
on Kawasaki KZ and Suzuki GS motors. A rule of thumb in jetting is to allow a spread
of 4 jet sizes between gas and NOS, with gas being the larger of the two sizes.
Battery ChargingWhen using a total loss ignition system where the charging system has
been removed the battery only takes 1-2 runs to lose its peak voltage. Re-charging
battery between rounds with a 5 amp charger will cure this problem.
ManifoldsFor those of you who are planning on running 40mm Mikuni Radial Slide
carbs on your '91-92' GSXR-1100 motors, use the intake manifolds from a 1988-89
GSXR-750 and match these to your intake ports.
Connecting RodsWhen installing Carillo rods on most late model sport bikes, you need
around .002 clearance on the big end of the rod. You need to use Plasti-Gauge to
determine how much clearance you have, then contact a dealer about bearing sizes
HorsepowerThe formula for figuring correct horsepower is RPM x Torque divided by
If you are using a car tire chassis with your Kawasaki motor,
it is a good idea to have a heavy-duty 2nd gear input installed in your transmission.
In a high-horsepower motor there is a tremendous load put on this gear when going
into 2nd gear, because of the traction the tire gives you.
Most racing engine applications use an octane rating of 108-114
when compression ratios of 12 to 1 or higher are used.
On turbo/nitrous applications where compression ratios of 8 or 9 to 1 are common,
an octane rating of 120 should be used. The higher the octane rating, the slower
the fuel is burned. This helps overcome detonation and pre-ignition when large amounts
of turbo-boost increase cylinder pressures causing heat build-up.
If you want more bottom-end torque, advance your intake cam by
For those of you running high-lift cams, .485-.507 lift Kawasaki
and .410-.420 lift Suzuki, we recommend changing your complete set of valve springs
every 15 passes for maximum performance.
If you are having problems with busted clutch plates in your
motor, Check the steel plates to see if they are warped. Clutch plates need to be
mated properly in order to get a proper grip and not distort.
CarburetorsFor those of you running 29 smoothbores on a mildly modified street machine,
here are some suggestions for carb modifications to give better mid-range performance:
# 20 Pilot Jets
# 0-4 Needle Jet
# 1.0 Air Jets
# 2.5 Needle & Set
* Float level heights, base of gasket to top of float 23.5 - 24.5mm
RingsWhen breaking in a new motor DO NOT use synthetic motor oil as rings
will not seal properly. Only use petroleum based motor oil.
Kaw Lock UpFor those of you setting up your Kawasaki lock up clutch: spring pressure
should be checked at .930? in a spring checker. You should look for around 40lbs
CamshaftsAnyone building a CBR 600 F2/F3 motor for formula car autocross competition
with a turbo charger may benefit by using a set of California EPA cams for these
engines. With added boost from a turbo you don?t need as much lift and duration
in the cam. The EPA California cams are .220 duration compared to the .235 duration
49 state cams of the regular CBR 600F2/F3 models. These are factory OEM camshafts.
NOTE: California cams only have .263 lift compared to .325 lift for the 49 state
PistonsWhen cutting the domes of blank pistons cores you must leave a minimum
of .150 piston dome thickness for aspirated motors and .300 for turbo charged applications.
ValvesWhen doing a street/strip port job on a GSXR-1100 water cooled head we
have found it very beneficial to go to a 1mm oversize intake valve.
NOSBefore filling that NOS bottle make sure it?s good and cold. Place bottle
for several hours in your freezer at home. NOS is under pressure at about 200 degrees
below zero. Getting the bottle cold allows it to pack more tightly by creating a
denser atmosphere. MAKE SURE BOTTLE STAYS COLD UNTIL YOU GET IT FILLED.
Exhaust PipesTired of that new chrome exhaust system turning blue after a couple of
passes? Paint the inside of megaphone and head pipes with header paint like VHT,
etc. The heat is reflected off the coating and out of the exhaust system. Heat does
not get absorbed as quickly through the pipe wall.
Chain AlignmentA neat little trick to get your chain properly aligned on the sprocket.
Measure from center of swing arm pivot bolt to center of rear axle. Make adjustments
to either side to get them exactly the same.
Front End StiffnessDon?t run too high an air pressure in your front tire. 30-35 lbs is satisfactory.
Keep front end springs on medium stiffness. Not following these steps can cause
the rear tire to lose traction at high end due to unloading of chassis.
Heavy Duty Cylinder StudsWhen installing studs in cases put a drop of red Lock Tite on threads
and torque to 10-12 ft lbs.
Suzuki 750 Straight Cut GearsAnyone installing these gears in their motor will need to take approximately
7 teeth off the rear wheel sprocket.
Intake ManifoldsAnyone planning on building a 1978 GS 1000 2V Suzuki and doing a semi-pro
ported head with 38 mm Lectron carbs, use Mikuni manifolds Part #VM 36 -200.
Valve SealsFinding it hard to install seals on late model GSXR heads with valve
tappets? Applying a little white lithium grease to an 8mm socket will hold seal
on socket, then press firmly and evenly into place.
Air Kill / Rev LimiterWhen wiring a two-step with an air shifter on your bike you need to wire
the air kill to wherever the tach source is (i.e. Dyna-4000 MSD box) so as not to
interrupt the two-step.
Valve Spring PressureWhen checking valve spring pressure on your Kawasaki KZ900/1000 or Suzuki
GS1100/1150, measure the seat pressure at 1.400? in a valve spring checker. Kawasaki
90-100 lb, Suzuki 55-60 lb.
Valve Spring PressureGS1100/1150 48-50 LB Street GS110/1150 55-60 LB Street
Cylinder HeadWhen installing a GPZ head on a KZ-1000 Kawasaki bottom end you must
install a cam conversion tower. If the crank has a 15 tooth sprocket use a 122 link
cam chain and KZ 900/1000 cam sprockets (30 teeth). If the crank has a 16 tooth
sprocket use a 124 link cam chain and Kawasaki MK II cam sprockets (32 teeth).
Wristpin ButtonsA method for determining what size teflon wristpin button you need is
to subtract the length of the wristpin from the bore size. Subtract .020 from this
figure, then divide by 2.
CrankshaftWhen using a GPZ crankshaft in your drag motor you should replace the
thrust bearing which is susceptible to failure with a needle bearing. Crank will
have to be disassembled. At this time it is a good idea to also have your crank
index trued and welded.
AirboxWhen running a full body and fairing combination on your drag bike it
is essential that you install an air box. The air is streamlined around your fairing
causing a dead air space in the area of your carburetors. This starves your carbs
of air and performance is dramatically decreased as much as three tenths or more.
Lining your air box with a heat reflecting material will keep engine heat out so
that you have clean cool air.
Street TiresFor you street racing fans here?s a hot tip for the stickiest tire that?s
DOT approved. Yokahama makes two compounds of this tire - either a D-003 or D-006.
Check your local dealers for a size that may be compatible with your bike.
Intake ManifoldsWhen mounting Lectrons on your Suzuki GS1100/1150 use Dayco Radiator
hose cut to 1-5/8? length. For 40mm Lectrons use 1-5/8? I.D. hose, for 44mm Lectrons
use 1-3/4? I.D. hose.
Oil LevelWhen changing oil in your drag racing motor never exceed 2-1/2 - 3 quarts.
This amount allows adequate lubrication while allowing minimum crank windage. Break
in new motors with good grade petroleum base 30w motor oil. We recommend a 5w-30
synthetic motor oil either Mobil 1 or Torco at oil changes.
Wheelie BarsIn setting up your wheelie bars we recommend painting your wheels with
white shoe polish. After making a run check wheels to see if both are having weight
applied equally. Adjust wheelie bar heim joints to compensate.
Fuel PressureIf you?re having trouble figuring out correct fuel pressure on your turbo
bike buy yourself a 16oz ratio-rite cup like the one moto-crossers use for pre-mixing
fuel. Disconnect fuel line going to carb and place in ratio-rite cup. Turn on fuel
pump switch and spin motor over with ignition off. Cup should fill in Approx. 15
seconds. If not, adjust fuel pressure regulator in either direction until result
Mikuni 33mm SmoothboresFor those of you who still own these carburetors a little jetting trick.
In order to get better throttle response install 0.6 air correction jets. This allows
you to run a smaller main jet while still giving you approximately the same air
fuel ratio as before. Good starting point is 4 main jet sizes smaller than you previously
had. Also installing a O-6 needle jet will help lean out the mid range.
Master LinkA good way to keep that master link clip from coming off of your chain
is to apply a small amount of clear silicone over the clip and let it harden.
SlicksWorn and dried drag slicks can come back to life with a paint brush and
a can of VHT traction compound available at your local speed shop. Apply a few coats
and let dry.
CoolingUse a portable fan hooked up to your generator to cool your motor down
OilingTo get maximum lubrication to your GS1100/1150 motor, remove stock oil
pump gears and replace with gears from a GS 750 4 valve model.
Camshaft LiftA simple method of determining the lift of your camshaft. With a vernier
caliper measure from heel of cam to nose, then subtract the base circle. This gives
total valve lift.
Tire Temperature/PressureA little trick that will keep your tires at a constant temperature and
pressure. Keep a nitrogen bottle with adapter and filler hose hook-up in your van.
Filling tires to recommended pressure with nitrogen keeps tires from growing on
hot days. Better foot-print maintained means consistent times while keeping chassis
from unloading due to traction loss.
Head Gasket SealingProper sealing of head gasket can be accomplished following these three
1. Have your cylinder o-ringed
2. Treat both sides of copper head gasket with a light film of Copper Coat, let
dry for 2-3 hours
3. Torque stock cylinder studs to 36 ft lb., heavy duty cylinder studs to 42 ft
Note: both head and cylinder surfaces must be parallel.
Piston to valve clearance ( minimum ): KZ / Z1 - 0.050 Int., 0.075 Ex.
GS 1100/1150 - 0.050 Int., 0.075 Ex.
Valve to valve clearance ( measured on the seat ): KZ / Z1 - .200
GS 1100/1150 - .100
Cam Timing: KZ 900/1000, GS1100/1150
naturally aspirated motors 110 both intake and exhaust.
GSXR (stock cam) - 105 both intake and exhaust
GSXR (G21X cam) - 106 intake, 108 exhaust.
Use Kaw "J" model manifolds for mounting Lectrons
or Mikuni RS carbs on your KZ/Z1.
Use 1-3/4" radiator hose for mounting Lectrons on
your Suzuki GS1100/1150.
Lectron carbs set needle height adjustment at 1.825
Valve spring seat pressure:
KZ / Z1 / GPZ - 100lb
GS1100/1150 - 55-60lb
Standard lock-up clutch
use O.E.M. Clutch Springs
Kaw KZ 900 / 1000 / GPZ
Single plug head - 38 degrees
Dual plug Head - 32 - 34 degrees
NOS motors - 26 - 28 degrees
Suz GS 1100 / 1150
Single plug head - 34degrees
Dual plug (2-valve) - 32 - 34degrees
NOS motors - 26 - 28degrees
Heavy-duty cylinder studs torque to 40-42 ft lb.
Heavy duty main studs torque to 20 ft lb.
Largest valves on a stock seat:
GS 1100/1150 - 28.5mm Int, 24mm Ex
GSXR 1100 - 30mm Int, 26mm Ex
KZ 900/1000 - 37.5 Int, 31mm Ex
KZ 1000J/GPZ - 38.6 Int, 33mm Ex
To Degree Cams: Install degree wheel and find TDC
with a positive stop. Setup dial indicator on valve and zero indicator with valve
closed. Rotate engine until valve is .050" off seat and write down reading on degree wheel. Continue to rotate engine until valve is .050" from closing. Note the number.
To figure lobe center for intake cam subtract opening number
from closing number, divide difference by two and add that number to 90. For the
exhaust subtract the closing number from the opening number and follow the same