These Tips were originally
posted on the Cope Racing website, which no longer exist. They
were authored by engine guru Greg Cope.
Many people missed these
tips when Greg shut the site down, so the fact that he is a good
friend, we thought it was OK to rip off his page and repost it
for everyone to enjoy. The page will stay up until we receive
the "cease and desist" letter from Greg's attorneys.
Most of this stuff applies
to the older Kawasaki KS and Suzuki GS style motors.
Technical tips are given
as a courtesy to the racer. Results achieved by these tips are
the sole responsibility of the racer.
When 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 airbox with a heat reflecting material will
keep engine heat out so that you have clean cool air.
If you want more bottom-end torque, advance your intake cam by
Anyone 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 cams.
A 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.
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.
Turbo Engine Timing
Turbo 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.
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 formula.
For 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
Mikuni 33mm Smoothbores
For 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
If 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 is obtained.
set needle height adjustment at 1.825 - 1.835.
For 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
Anyone 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.
When 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.
Use Kaw "J"
model manifolds for mounting Lectrons or Mikuni RS carbs on your
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.
Standard lock-up clutch
use O.E.M. Clutch Springs
For 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 per spring.
When installing Carillo rods on most late model sportbikes, 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 needed.
Use a portable fan hooked up to your generator to cool your motor
down between rounds.
When 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.
When 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).
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
Largest valves on
a stock seat:
GS 1100/1150 - 28.5mm Int, 24mm Ex
GSXR 1100 (oil cooled) - 30mm Int, 26mm Ex
KZ 900/1000 - 37.5 Int, 31mm Ex
KZ 1000J/GPZ - 38.6 Int, 33mm Ex
Tired 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.
Front End Stiffness
Don'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.
On 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 ar 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
Do not use a Copper Head
Gasket on a watercooled 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 headgasket and do not o-ring the cylinder.
Head Gasket Sealing
Proper sealing of head gasket can be accomplished following these
1. Have your cylinder
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 lb..
Note: both head and cylinder
surfaces must be parallel.
The formula for figuring correct horsepower is RPM x Tourque
divided by 5250
For 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 motor.
When using a Vance &
Hines Powerpak Ignition on your sportbike, use 3 OHM coils with
graphite suppression wires. With a Dyna-2000 Ignition, use 2.2
OHM coils with the same type of wire.
Air Kill / Rev Limiter
When 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.
When running a motor at high altitude you must advance the ignition
Example: a Suzuki GS 1100/1150 motor running at 4000 feet above
sea level would advance the ignition timing approximately 3-4
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
When 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.
Spark Plug Gaps
When 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.
Racing 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.
If 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 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.
Before 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.
When 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.
When 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.
When breaking in a new motor DO NOT use synthetic motor oil as
rings will not seal properly. Only use petroleum based motor
Kaw Lock Up
Piston To Valve Clearance
For 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 above.
A 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.
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.
Heavy Duty Cylinder
When installing studs in cases put a drop of red Lock Tite on
threads and torque to 10-12 ft lbs.
torque to 40-42 ft lb.
Heavy duty main studs
torque to 20 ft lb.
Worn 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.
A 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.
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.
Suzuki 750 Straight
Anyone installing these gears in their motor will need to take
approximately 7 teeth off the rear wheel sprocket.
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.
Valve Spring Pressure
When 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 Pressure
GS1100/1150 48-50 LB Street GS110/1150 55-60+ LB Race
When 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
Finding 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
In 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.
To get maximum lubrication to your GS1100/1150 motor, remove
stock oil pump gears and replace with gears from a GS 750 4 valve