Page 1
2006 CM-50
Owners Manual
Allegan Motorsports - 800-475-5660
June 2006
Page 2
For parts orders contact your local dealer
To
locate your closest Cobra dealer
log
on to
the
www
.cobramotorcycle.com
or call
(330)
you need technical assistance
If
contact
your local dealer or call
549-9600
Cobra Technical Support Hotline at
(330)
549-9603
Cobra Motorcycle MFG., Inc.
11511 Springfield Road
North Lima, Ohio 44452
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MCCM2006.2
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DISCLAIMER OF WARRANTY
This motorcycle is sold “as is” with all faults, obvious or not. There are no warranties
expressed or implied, including any warranty of merchantability and warranty of fitness
for any particular purpose.
“WARNING”
THE COBRA CM50 IS A COMPETITION MODEL ONLY AND IS NOT
MANUFACTURED FOR, NOR SHOULD IT BE USED ON PUBLIC STREETS, ROADS
OR HIGHWAYS.
THE USE OF THIS BIKE SHOULD BE LIMITED TO PARTICIPATION IN
SANCTIONED COMPETITION EVENTS UPON A CLOSED COURSE BY A
SUFFICIENTLY SKILLED RIDER AND SHOULD NOT BE USED FOR GENERAL
OFF-ROAD RECREATIONAL RIDING.
IMPROPER USE OF THIS MOTORCYCLE CAN CAUSE INJURY OR DEATH.
THIS BIKE IS INTENDED FOR EXPERIENCED RACERS ONLY AND NOT FOR
BEGINNERS.
IT IS YOUR RESPONSIBILITY AS THE OWNER OF THIS COBRA MOTORCYCLE
OR AS THE PARENT, OR LEGAL GUARDIAN OF THE OPERATOR, TO KEEP THIS
COBRA MOTORCYCLE IN PROPER OPERATING CONDITION.
THIS BIKE WAS DESIGNED FOR RIDERS THAT WEIGH LESS THAN 80 LBS WITH
FULL RIDING GEAR AND SHOULD NOT BE OPERATED BY RIDERS THAT WEIGH
MORE THAN THAT.
BE SURE THAT THE RIDER ALWAYS WEARS ADEQUATE SAFETY GEAR
EVERYTIME HE OR SHE RIDES THEIR COBRA MOTORCYCLE.
IMPORTANT SAFETY NOTICE
Failure to follow WARNING instructions could result in severe injury or death to
the machine operator, a bystander, or a person inspecting or repairing the
machine.
CAUTI ON:
A CAUTION indicates special precautions that must be taken to avoid damage to
the machine.
NOTE:
A NOTE provides key information to make procedures easier or clearer.
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Table Of Contents
General Information .........................................................................................................5
Specifications - General..............................................................................................5
Specifications - Torque Values ..................................................................................6
Optional Components..................................................................................................7
Break-In Procedure......................................................................................................8
Starting Procedure .......................................................................................................9
General Tips................................................................................................................10
Maintenance....................................................................................................................11
Schedule & Tips .........................................................................................................11
Replacing Transmission / Clutch Lubricant............................................................12
Chain adjustment .......................................................................................................13
Front brake adjustment .............................................................................................14
Rear brake adjustment ..............................................................................................15
Air Filter Cleaning .......................................................................................................15
Fork Oil Replacement................................................................................................16
Servi
ce .............................................................................................................................40
Engine Service............................................................................................................40
Engine Removal .....................................................................................................41
Complete Engine Disassembly Procedure.........................................................42
Top End Disassembly Procedure ........................................................................42
Splitting the Cases .................................................................................................43
Engine assembly ....................................................................................................44
Clutch ...........................................................................................................................46
Ignition..........................................................................................................................51
Cooling System...........................................................................................................53
Fuel & Air System.......................................................................................................57
Exhaust ........................................................................................................................60
Wheels & Tires ...........................................................................................................61
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ng ..............................................................................................................................61
Tuni
Suspension..................................................................................................................61
Rear shock ..............................................................................................................63
Front Forks ..............................................................................................................63
Gearing ........................................................................................................................64
Carburetion..................................................................................................................66
Troubleshooting ..............................................................................................................68
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General Information
Specifications - General
Items CM 50
Dimensions
Wheelbase 35.75” (908mm)
Wheel size 10” (254mm)
Seat height 23.9” (607 mm)
Engine
Type 2-stroke, single cylin der, reed valve
Cooling system Liquid-cooled
Coolant Liquid Performance Mini Coolant or Antifreeze
Displacement 49.8 cc
Bore and stroke 39 mm x 41.7 mm, “V” head
Ignition system Electronic, analogic advance
Spark plug Champion 8339-1, 8332-1 hotter, 8904-1 colder
Gap 0.023” – 0.025” (0.58 – 0.64 mm)
Ignition timing 0.045” (1.14 mm) Before To Dead Center (BTDC)
Fuel type High octane pump gasoline
Oil type Cobra Venom 2-cycle Race Oil
Fuel / oil mix ratios Between 32:1 and 40:1 (after engine Break-In)
Carburetion 14 mm Dell’Orto
RACE FUELS ARE NOT RECOMMENDED
Main Jet 92
Slow (Pilot) jet 55
Float Height 16mm + 0.5mm (0.63” + 0.020”)
Transmission
Speed / Clutch Single / Cobra 3 shoe
Final drive ratio 13/38T or 14/38 T
Chain 420
Transmission / clutch oil type Cobra Venom 3 Shoe Clutch Milk
Quantity 235 ml (8.0oz)
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Chassis
Front tire 2.50 – 10
Pressure 15 psi minimum
Rear tire 2.75 – 10
Pressure 15 psi min. (20 psi for hard pack or rocky conditions)
Front fork Marzocchi 32mm
Fork oil type SAE 20 weight
Fork oil amount 200 ml (6.8 oz) oil change, 220 ml (7.4 oz) rebuild
Collapsed fork oil height 70 mm (2.75”) spring in, no spacer
Specifications - Torque Values
Torque Value
Fastener
Cylinder head nuts
Crankcase bolts
Spark plug (SP) (SP) (SP) M14 x 1.25
Stator bolts 2.1 25 2.8 M5 X 0.8
Stator cover bolts 1.7 20 2.3 M4 X 0.75
Clutch cover bol ts 5.8 70 7.9 M6 X 1.0
Clutch nut (max.) 40 480 54 10 x 1.25*
Clutch bolts 12 144 16 M6 x 1.0
CFD nut 55 664 75 ½” x 20 LHT
Engine mount bolts 22 265 30 M8 X 1.25
Swingarm Pivot 21 250 28 M14 X 2.0
Intake manifold bolts 4.6 55 6.2 M6 X 1.0
ft-lb in-lb Nm
8.8 105 12
8.8 105 12
Size &
Remarks
M6 X 1.0
M6 x 1.0
Ignition rotor nut 40 480 54 M10 x 1.25*
Rear Sprocket Bolts 18 216 24 M7 X 1.0
Rear shock mounts 40 480 54 M10 x 1.5
Axle nuts 25 300 34 M12 X 1.25
* Apply high strength thread locking agent when installing
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(SP) To apply the proper torque to the spark plug when inserting, one must first
screw the spark plug in until the metal gasket ring causes resistance and then
turn another 1/8 to ¼ turn.
Optional Components
Call your dealer, or the factory, for details
• Carburetor jets
• Pre-filter for the airbox
• Sprockets
o Front
o Rear
• Suspension Springs
Weight of Rider (lb) Fork Spring Shock Spring
Less than 38 (light) KCMZ0012A
(12 lb/in, 2.10 N/mm))
38 – 45 (std) KCMZ0012
(14 lb/in, 2.45 N/mm))
46 to 55 (stiff) KCMZ0012B
(16 lb/in, 2.80 N/mm)
• Suspension valving
Damping Rate Fork Valving
Compression
(right)
Soft (fast) KCMZ0033A KCMZ0032A SCMUOH07
Standard KCMZ0033 KCMZ0032 SCMUOH08
Hard (slow) KCMZ0033B KCMZ0032B SCMUOH09
• Tires
• Tubes or ‘Tire Balls’
Fork Valving
Rebound
(left)
SCMUOH04
(275 lb/in) red
SCMUOH05
(285 lb/in) yellow
SCMU0H06
(295 lb/in) white
Shock Valving
(kit)
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Break-In Procedure
Your Cobra CM50 is a close-tolerance high performance machine and break-in
time is very important for maximum life and performance. The CM50 can be
ridden hard after the first ½ hour break-in time but it is recommended that no
adjustments are made to the carburetion or suspension until the full 8 hours of
bike break-in has elapsed. Also, after the engine, transmission, and drive train
have been broken-in for the full 8 hours, the bike will be faster!
Use a fuel / oil mixture of 32:1 for the full 8 hour break-in period. Be sure to use
high octane pump gas with Cobra’s specially formulated Cobra Venom 2-cycle
Race Oil
CAUTION:
Failure to use proper fuel, oil, or fuel/oil mixture may result in premature engine
wear or damage to the machine.
Adhering to the following break-in schedule will result in long lasting high
performance machine.
• Start bike on stand
• First 5 minute period, operate the bike on the stand with a combination of idle
and high RPM operation. (avoid prolonged high RPM but spin the rear
wheel good at least once or twice per minute)
• Allow bike to cool
• Ride for 15 minutes maximum (avoid prolonged high RPM operation and
avoid abusing the clutch with throttle blipping.
• Cool and inspect bike for loose fasteners.
• Next ½ hour of operation, avoid prolonged operation at Wide Open Throttle.
• After 1 hour of operation
o Check for loose bolts and nuts on the bike and retighten as
necessary (proper toque values are listed under Specifications).
o Clean the carburetor bowl.
o Change the transmission / clutch lubricant.
• After 8 hours of operation
o Change the fork oil.
o Have a Certified Cobra Mechanic change the shock oil.
• Your bike is now ready for the highest level of competition!
NOTE:
During break-in the bike will likely lose some engine coolant through the radiator
overflow hose. Losing up to 4 oz (120 ml, ½ cup) is normal. Proper coolant level
will cover the top of the radiator cores. Removing the radiator cap and looking
inside is the only way to check the coolant level.
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Never open the radiator cap of a machine that has a hot or warm engine or one
that has recently been ridden. Burning and scalding could occur.
CAUTION:
It is important that the radiator cap is installed correctly and completely otherwise
engine damage could occur.
Starting Procedure
Before starting the machine inspect the following:
• Make sure vehicle is properly maintained (see Schedule & Tips in the
Maintenance section)
• Check the throttle for smooth operation and sound closing.
• Insure that the fuel tank contains an adequate volume of fuel / oil mixture to
complete the distance required. (High octane pump gas with Cobra’s
specially formulated Cobra Venom 2-cycle Race Oil)
• Turn the fuel on by rotating the fuel petcock knob to the vertically downward
position (reserve position is horizontally forward)
CAUTION:
For best results from your Cobra Motorcycle use only the recommended fuels.
Testing has shown that most ‘race’ fuels actually degrade performance.
When your pre-ride inspection is complete the bike may be started. For a cold
engine follow this procedure.
1. Place the motorcycle on a stand of sufficient strength that positions the
motorcycle in a level upright position with the rear wheel off the ground.
2. Pull up the choke knob and turn it to lock it.
3. Kick start the engine.
4. Rev the engine in short spurts, turning the throttle no more than 1/4 open
until the engine will run without the choke.
5. Verify a functional engine shut-off switch by shutting off the engine.
6. Restart the engine and proceed with riding when the engine is sufficiently
warm (i.e. the side of the cylinder is warm to touch).
CAUTION:
Never rev an engine full throttle when it's cold or slightly warmed up. Cobra
recommends that you tell your child to take it easy the first couple of minutes in
practice until the engine comes up to full operating temperature. Make sure your
engine is properly warmed up before racing.
This is a high performance race motorcycle. Too much application of throttle will
likely land your little racer on his or her arse. Fenders can be replaced but
bruised egos and other body parts take longer.
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General Tips
1. Always wear a helmet and other protective riding gear.
2. Cobra recommends that you tell your child to take it easy the first couple of
minutes in practice until the engine comes up to full operating temperature.
3. Make sure your riders’ foot is not resting on the foot brake while they are
riding.
4. Evaluate the bikes jetting only after it has been warmed up to race
temperatures.
5. A properly maintained machine is safer, faster, and more fun to ride.
6. Cobra offers a carburetor inlet cover RCMU0109 to keep water and dirt
from getting into the carburetor when the bike is being washed.
7. New chains will stretch on first use. Never install a new chain prior to a
race. Always ‘break’ them in during practice.
8. Your Cobra Motorcycle has a 10 digit VIN (Vehicle Identification Number).
The first two digits indicate the model and the seventh indicates the model
year (MY).
a. Example, CMxxxx6xxx is a 2006 Model Year CM50.
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Maintenance
Schedule & Tips
It is important that you adhere to this maintenance schedule so as to promote the
longevity of your Cobra Motorcycle.
• Between each ride
o Check the air filter (clean and re-oil as necessary).
o Insure the smooth operation of the throttle cable (throttle soundly
‘clacks’ shut).
o Check for frayed strands of the throttle cable inside the throttle housing
and replace if necessary.
o Check for adequate tire pressures and adjust if necessary.
o Check all nuts and bolts for proper torque and re-torque if necessary.
o Spray all moving parts with WD40 or other light oil.
o Check drive chain for
§ Proper tension and adjust if necessary.
§ Adequate lubrication and lubricate if necessary.
o Insure that the ignition stator and rotor are clean and dry.
o Check the frame for cracks in the metal or cracks in the paint that
might indicate that the metal has been stressed beyond it’s safe limits.
Replace or get properly rewelded as necessary.
• Every 2 hours of operation
o Replace the transmission oil.
• Every 10 hours of operation
o Replace the fork oil.
o Hav e the shock oil replaced by a Certified Cobra Mechanic.
CAUTION:
1. Because of the amount of heat generated by the clutch and engine during
extended periods of riding, it is advisable to remove the ignition cover
afterward to allow the ignition to cool off. The heat transfers through the
cases and can damage the stator as it cools off because of lack of airflow
around the stator.
2. If you ever need to weld anything on the bike, disconnect the spark plug
cap, unplug the ignition, disconnect the kill switch, scrape the paint bare
near the area to be welded and put the ground clamp as close to the area
to be welded as possible.
3. Inspect CFD every couple months and replace paper when thickness is less
than 0.6mm.
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Be sure the fuel tank and carburetor have been removed and safely located
away from the welding process.
4. The frame is 4130 Chrome Moly and it is important to weld it with the proper
rod and heat settings set as light as possible. Cobra recommends replacing
the frame with a new one if the old one becomes damaged.
5. If your kick-starter lever does not return properly, first try loosening the six
kick/clutch cover screws ½ turn. Hold the kick lever ½ way down while
retightening the six screws starting for the center and working out.
Replacing Transmission / Clutch Lubricant
Tools needed:
• 225 ml (7.6 oz) Cobra Venom 3 Shoe Clutch Milk.
• 13 mm combination wrench
Procedure:
1. Begin this procedure with a bike that has been ridden more than 5 minutes
but less than 10 minutes. It is desired to have the engine warm enough so
that the oil is ‘runny’ but not so hot that there is risk of being burned by the
engine or the oil.
Hot oil and hot components on the
motorcycle may cause burns.
2. Lean the bike against something or set
on stand with oil drain hole.
3. Using a 13 mm wrench, remove the oil
drain bolt located on the right side of
the engine, on the clutch cover, near
the brake lever (Item 2, figure 1).
NOTE: You may need to adjust the brake pedal (up or down) to gain access to
the drain bolt.
4. After it has drained, reinstall the bolt being sure that the copper gasket is in
place. Torque to 15 Nm (11 ft-lb).
5. Reapply oil from oil fill plug 235 cc Cobra Venom 3 Shoe Clutch Milk thru the
fill plug.
Allegan Motorsports - 800-475-5660
Figure 1
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June 2006
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NOTE:
Lean bike over onto it’s left hand side so that the clutch cover is up unless you
have a squeeze bottle.
6. Reapply the oil fill bolt, hand tight, being sure the fiber gasket is in place.
CAUTION:
Cobra has spent considerable time and money developing the proper lubrication
to handle the harsh environment of the automatic clutch and transmission of this
motorcycle. Cobra’s specially developed Cobra Venom 3 Shoe Clutch Milk was
formulated to provide superior lubrication and cooling capability over
extended periods of time and is the recommended lubricant for your Cobra
motorcycle.
Chain adjustment
Tools required for chain adjustment
• 19 mm wrench or socket
• 13 mm wrench or socket
1. Make sure that the rear wheel is
aligned properly.
2. For proper adjustment, the chain
should have 35 mm (1 3/8”) free
movement just behind the chain
block with no load on the bike
(figure 2)
CAUTION:
Sit on the bike and verify that the chain has a minimum of 12mm (1/2”) free
movement when the chain is at it’s tightest point.
Allegan Motorsports - 800-475-5660
Figure 2
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June 2006
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3. If the chain requires adjusting, loosen the
axle with a 19 mm wrench and tighten the
chain by rotating the adjustor bolts
clockwise (CW) or loosen the chain by
rotating the adjustor bolts (CCW).
4. Retighten the axel bolt to 25 ft-lb (34 Nm).
5. Retighten the adjustor bolt
Figure 3
CAUTION:
Always check rear brake adjustment and free-play after adjusting the chain.
Front brake adjustment
Tools recommended for front brake maintenance:
• 10mm open end wrench
Figure 3, from the brake lever Figure 4, from the brake hub
From the brake lever:
1. Slide the cover out of the way
2. Loosen the locking nut on the brake lever.
3. Adjust the bolt to desirable position.
4. Tighten the locking nut.
5. Slide the protective cover back over the lever pivot and adjustor
From the brake hub:
1. Loosen the 10mm nut on the hub.
2. Adjust the brake cable to desirable position
3. Tighten the 10mm nut.
CAUTION:
If y ou tighten the front brake up too much, the brakes may hang up causing the
brake pads to wear incorrectly and prematurely.
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Rear brake adjustment
Tools recommended for rear brake maintenance:
• 10mm open end wrench
There are 2 adjustments on the brake.
Figure 5, adjust brake lever free height Figure 6, adjust brake lever ‘free play’
From the brake lever:
6. Loosen the 10mm nut on the back of the brake pedal.
7. Adjust the bolt to desirable position
8. Tighten the 10mm nut.
From the brake hub:
1. Adjust the wing nut to the desirable position.
CAUTION:
If you tighten the wing nut too much, the brakes may hang up. If so, the brake
pads will burn up, and need to be replaced.
Air Filter Cleaning
Tools recommended for air filter maintenance:
• #2 Phillips head screwdriver
• 4 mm hex key (Allen)
• Foam filter oil
Procedure
1. Removed the seat with the 4 mm hex key
2. Remove the filter/air inlet boot from the back of the carburetor with a phillips
screwdriver
3. Pull the filter / boot assembly back, up, and out the top of the airbox.
4. Clean the filter in a nonflammable solvent to remove the filter oil.
Do not clean the air filter with gasoline or other highly volatile petroleum product.
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Diesel fuel or kerosene would be preferred but caution should still be taken. Hot
soapy water works well.
5. Clean the filter in hot soapy water to remove all dirt particles.
6. Allow it to dry thoroughly.
7. Saturate with filter oil and remove excess.
NOTE:
The Cobra is equipped with a special designed Air box. It is very important to
keep the air filter clean and properly oiled with high quality water-resistant foam
filter oil. It’s very important to oil your filter consistently each time because varied
amounts of oil will change your carburetor jetting.
8. Reinstall the filter / boot assembly by pushing it down and forward into the
airbox making sure the letters “CM” are visible between the carburetor and
airbox (figure 8).
Figure 8
NOTE:
Make sure you change or clean your filter after each moto. We recommend
carrying multiple filters in your toolbox, one for each practice session and moto.
Fork Oil Replacement
Tools required
• 5 & 6 mm Allen wrench
• 19 mm wrench or socket (two required)
• Spring clip remover
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Disassembly
1. Remove the front wheel.
2. Remove the fork legs from the triple clamps.
3. Perform the following on one leg at a time.
4. Using your hands, remove the black rubber plug from the top of the fork leg
exposing the white plastic cap.
5. Secure the fork leg assembly in a vice by gripping the leg across the flats
through which the axle bolt goes through.
6. Depress the white plastic cap inwards (down) and remove the wire spring clip
from its groove.
7. Remove the white cap, the fork spring preload sleeve, and the fork spring.
NOTE: Depressing the fork leg will facilitate removing the white cap.
8. The fork can now be turned upside down and drained.
Assembly
1. Fill the leg with 200 cc (6.8 oz) 20 wt fork oil.
2. Standard fork oil level is 70 mm (2.75”) from the top edge with the fork
collapsed.
NOTE: Remove the preload sleeve but leave the spring in for the measurement.
3. Install the preload sleeve.
4. Install and depress the white cap while installing the spring clip.
5. Fork may be reinstalled.
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Service
Trained technicians with precision gauging and proper assembly fixtures carefully
assemble all Cobra engines to specific tolerances. If you feel you have the skills,
and the appropriate tools, to perform the following service tasks please follow the
instructions closely. The part numbers are listed throughout to help you when
ordering parts from your local Cobra dealer.
If you don’t feel comfortable with the service work, simply take your engine out of
the frame and sent it to:
Cobra Motorcycle Mfg.
11511 Springfield Road
North Lima, Ohio 44452
Cobra has specialized mechanics that will go through the entire engine, replacing
gaskets, bolts, or any old part that is worn. The engine will be rebuilt using the
same precision gauging and assembly fixtures as when it was assembled new.
Before leaving the engines performance will be measured on a dynamometer to
ensure that your engine is operating at its highest potential. All of this for one low
nominal fee please call (330) 549-9603 for details.
Engine Service
One method for determining whether the top end of your engine needs rebuilt is
to perform a WOT (Wide Open Throttle) kicking compression test. Before
performing the procedure please read the caution notes below.
CAUTION:
• There appears to be a wide range of variability in reading compression
gauges across the country.
• The head volume of this Cobra Motorcycle is very small and so requires many
kicks ~20 before you establish the most accurate reading possible.
• Because of the geometry of the spark plug used in this Cobra Motorcycle, the
adapter used with your compression tester must have a similar volume
protruding into the combustion chamber to establish an accurate value.
• Length of hose on the compression tester will affect the reading. The shorter
the hose length the more accurate your reading will be.
Because of these difficulties in measuring an absolute compression value, a
useful relative value can be achieved by testing your bike’s compression with
your own particular gauge after a new top end or when the bike is new so that
you know what your particular gauge reads on a ‘fresh’ engine. When it has
Allegan Motorsports - 800-475-5660
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June 2006
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dropped to 90% of its original value the engine will be down on power and would
benefit from a rebuild. When it’s dropped to 80% it really needs rebuilt! Using the
table below will help you determine monitor the condition of your top end.
Example
Engine is Fresh
Measured
Value
110 psi 110 psi * 0.9 = 99 psi 110 psi * 0.8 = 88 psi
Engine
Down on Power
Measured Value * 0.9
Engine
NEEDS Rebuilt
Measured Value * 0.8
Your Values
Procedure for Compression Testing
1. Shut off the fuel petcock.
2. Install the compression gauge into the spark plug hole.
3. Hold the throttle to wide open, and kick repeatedly (approximately 20
times) or until the gauge reading does not increase in value with each kick.
Engine Removal
To service the bottom end or transmission, the engine must be removed from the
frame.
Tools required
• 10, 11, 13, 22 mm wrench
• 8, 10, 14, 17 & 19 mm sockets
• 3, 4 & 5 mm hex key (Allen wrench)
• 7 mm nut driver, flat or Phillip, screwdriver for hose clamps
• Spring remover
• Flywheel / clutch puller.
• Clutch nut removal tool (Call local dealer for details).
Procedure
1. Remove the seat.
2. Turn of the fuel at the petcock and disconnect the fuel line.
3. Remove the tank (8 mm socket).
4. Remove the carburetor from the inlet (flat head or Phillips head
screwdriver, 7 mm nut driver).
5. Remove the silencer & pipe (spring remover, 8mm socket).
6. Locate a suitable container for the engine coolant and disconnect the
coolant lines connected to the engine (8 mm socket).
NOTE:
If the coolant looks to be free of contaminates it may be reused.
7. Remove the master link from the chain.
8. Remove front engine mount bolt (13 mm socket, 6 mm hex key).
9. Remove the swingarm bolt (22mm socket).
Allegan Motorsports - 800-475-5660
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NOTE:
Only drive the swingarm bolt far enough to clear the engine, leave it holding the
one side of the swingarm to the frame
10.Remove the engine from the right side of the frame.
NOTE:
If you are merely performing a top end service skip ahead to Top End
Disassembly Procedure.
Complete Engine Disassembly Procedure
1. Remove the magneto cover (4mm hex key)
2. Remove the bolt from the water pump shaft (4mm) and slide off the belt
cover and the water pump belt
3. Using a flywheel holding tool and 14 mm socket remove the nut that
secures the flywheel.
4. Using the Cobra flywheel / clutch puller, remove the flywheel from the
crankshaft
5. Remove the stator (5mm hex key).
6. Remove the nut holding the large gear to the transmission input shaft (19
mm socket).
7. Remove the special nut / starter gear that holds on the clutch (special tool
available, contact your local dealer).
8. With the Cobra flywheel / clutch puller, remove the clutch from the crankshaft
(de
tails in Clutch Service portion of this manual).
.
Top End Disassembly Procedure
1. Remove the cylinder head nuts (11mm).
2. Remove the cylinder head outer.
3. Remove the cylinder head insert.
Allegan Motorsports - 800-475-5660
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INSPE
CTION NOTE:
INSPECTION NOTE:
Inspect the cylinder head for deposits and abrasions.
1. If there are deposits they should be removed
a. Black oily deposits (indicating a rich mixture or improper oil
type/quantity) can be removed with solvent
b. Crusty deposits (indicating dirt ingestion) can be removed with
solvent and may require some scraping.
2. Abrasions
a. Pitting or erosion indicates detonation and may require cylinder
head replacement, also
i. Retard the ignition timing
ii. Use a higher octane fuel
b. Missing chunks or indentations indicate broken hardware or
ingested items - replace the cylinder head.
4. Remove the cylinder.
Inspect the cylinder bore for abrasions, deposits, and missing coating.
1. If abrasions: scrapes, scratches, pitting, etc… are found, replace the
cylinder.
2. If deposits are all are found
a. Clean with muratic acid.
b. Once the deposits are removed, inspect for abrasions and missing
surface coating.
i. If there are abrasions or missing coating, replace.
ii. If all looks well, the cylinder may be saved.
Muratic acid can be dangerous. Follow the manufacturers instructions closely.
INSPECTION NOTE:
Inspect the piston for abrasions and deposits on the top and sides and clean or
replace as necessary.
INSPECTION NOTE:
Piston ring end gap should be between 0.008” (0.2 mm) and 0.020” (0.5 mm)
Splitting the Cases
1. Remove the fasteners holding the two halves of the crankcase together.
2. Separate the cases with a proper case splitting tool.
5. Remove the piston clip with a scribe.
6. Remove the piston pin with a piston pin remover.
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CAUTION:
Take caution when handling the crankshaft. It is the main power transfer to the
rest of the engine. If it is out of alignment, it will cause premature failure of your
bearings which can lead to serious damage to the cylinder as well as the rest of
the engine. Do not try to true the crank yourself. Truing the crank should be
done professionally.
CAUTION:
• If you split the cases, check the gear tooth faces for chipping & signs of
fatigue.
• Check the small needle bearings for fatigue. If the bearings are damaged,
the engine cases should be checked to make sure the needle-bearing casing
didn’t oblong the bearing hole in the case.
• Needle bearings should be replaced every couple months of hard racing.
Engine assembly
CAUTION:
For any seals that are to be installed, apply a light amount of grease to the seals’
ID, assembly lube on all bearings and a small amount of Loctite to the OD.
1. Press the three bearings into the respective holes in each case half.
2. Press in the crank seals such that the concave side faces the crank weights.
3. Press in the counter shaft seal (concave side faces inside of transmission)
4. Install the water pump assembly wire ring retainer
5. Press in the water pump assembly
6. Tap both ways axially then verify easy rotation.
7. Inspect the crankshaft for proper true geometry (no more than 0.002 “,
0.05mm, measured at bearing journal area while supported from the ends).
CAUTION:
Insert a 7.05mm (0.278”) shim between the crank throws before pressing on the
crank.
8. Insert the screws with the proper lengths at locations shown.
Figure 21
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9. Torque to 12 Nm (105 in-lb) in the pattern shown in figure 21.
10. Trim away any excess gasket material if necessary.
NOTE: Check engine mount holes for excess material that may cause problems
in engine installation.
11. Install the piston with new wrist pin bearing and, pin and clips.
CAUTION:
Be sure to align the piston such that the arrow on the top piston surface points to
the exhaust (front of bike/engine) and put assembly lube on the connecting rod
bearing.
12. Install the piston rings.
CAUTION:
Ring end gap should be no less than 0.25 mm (0.010”) and no
more than 0.64mm (0.025”)
13. Install the base gasket.
14. Install the cylinder being sure that the piston rings are
properly aligned with the indexing pins.
CAUTION:
Never force the cylinder. If resistance is felt, determine the
problem and solve it. Once installed slightly rotate the cylinder
back and forth insuring that the rings are properly seated.
15. Install cylinder head insert.
NOTE: A light application of silicone grease can help hold the
o-rings into position during assembly.
16.Pressure test the engine insuring an acceptable leakdown
rate.
17.Install o-rings as shown in figure 22.
Figure 22
18.Install the cylinder head.
19.Install the washers (with flat side down) and nuts. Torque to 105 in-lb (12 Nm)
20.Install reed and inlet manifold with new gaskets (105 in-lb, 12 Nm) applying
1104 gasket sealer to both sides of all gaskets.
21.Leak check the engine to 20 psi to ensure proper seal.
22.Install stator reinstalling the grommet and wires (snug the bolts).
23.Install the rotor per Rotor Installation section, under the S3: Ignition portion of
this manual.
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24.Install the water pump outlet pipe (apply Ultra black Hi-Temp RTV silicon
gasket maker to the threads before assembly) before installing the clutch and
rotate to a vertical position with the engine resting on a bench
25.Install the clutch per Clutch Installation section in this manual.
26.Install the coolant drain plug with copper washer (11 ft-lb, 15 Nm).
27.Make sure that the exhaust spacer is on the cylinder (53 in-lb, 6 Nm).
28.Install the spark plug with a fresh gasket (to apply the proper torque to the
spark plug when inserting, one must first screw the spark plug in until the
metal gasket ring causes resistance and then turn another 1/8 to ¼ turn).
Clutch
CAUTION:
The clutch components (arbor, shoes, bolt, and Belleville washers) on your 2006
Cobra are similar looking but different in geometry from prior years. Do not mix
old and new parts as damage will occur.
Cobra clutch puller assembly:
Figure 23 Figure 24 Clutch puller installation
Tools recommended for clutch service:
• Universal clutch puller- a universal puller that pulls the clutch, main drive gear
and rotor.
• 5mm T-handle
• Clutch nut removal tool.
• Cobra 3 Shoe Clutch Milk.
CLUTCH REMOVAL:
1. Drain the engine transmission oil.
2. Remove the clutch nut (not left hand thread) on the end of the crankshaft with
the clutch nut removal tool.
3. Attach the Universal Puller. There are three 6mm clutch puller holes located
on the ends of the center hub. (figures 30 & 31) You must use a draw type
puller to remove the clutch.
CAUTION:
Do not use a jaw type puller or use the 6mm tapped holes as jackscrews or you
are likely damage the clutch or drum.
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4. If necessary apply heat to the center clutch hub.
CAUTION:
Do not heat the crankshaft threads or the aluminum shoes.
5. Keep tension on the puller as you are heating it.
The clutch will often pop off under tension from the puller and it will be very hot.
CLUTCH WASHER STACKUPS:
Once the clutch is removed, and cool to touch, carefully put it into a vice and
remove the center shoulder bolt out of each clutch shoe. You will probably have
to heat the center hub again to remove the bolts. Once you get a bolt loosened,
carefully remove it with the shoe and observe the way the spring washers are
stacked. Clean the washers and bolt if you intend to reuse.
The spring stacks in your 2006 Cobra clutch will contain 11 individual springs and
a flat washer configured as a 5 ½ stack. See figure 32. This clutch is designed
such that it reconfigured by the customer to achieve different clutch
engagements ‘hits’ by changing washer counts and configurations.
CAUTION:
Generally reassemble the springs as you removed them from the engine or as
you received them from Cobra. This will be either a 3, 4 ½ or, 5 stack. If you are
unsure call the Cobra Technical Support Group 330 549 9600, and consult the
experts.
CLUTCH ASSEMBLY REFERENCE DRAWING
REF # DESCRIPTION
1 Set of three shoes, springs, bolts, flat washers & nuts
2 Set Of three springs, washers, bolts & nuts
4 One metric clutch bolt
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Figure 32 Some configuration of clutch spring stack. Each ‘spring’ stack contains multiple
springs
against the flat washer(s). Shown is the 4 ½ stack..
(Belleville washers) - arranged into three, four, or five ‘flying saucers’, or turned away
Stack Total
Springs
Flying Saucers
or Cymbal Pairs
Turned Away
or Dish Stacked
Std. Flat
Washer
5 ½ 11 5 1 0.79mm (0.031”)
Clutch adjustment washers
Your Cobra comes stock with a single flat washer at the bottom of the spring
washer stack. The thickness of that flat washer is 0.031” (0.79mm). Cobra offers
several thicknesses of thin adjustment washers that allow clutch engagement
tuning. Increasing the flat washer(s) thickness increases the engine speed for
clutch engagement thus increasing the abruptness of clutch engagement (harder
hit). Conversely, decreasing the flat washer(s) thickness decreases the engine
speed for clutch engagement thus decreasing the abruptness of clutch
engagement (softer hit).
Part # Thickness mm (inch)
HCWS0801 1.4 (0.056)
HCWS0802 1.2 (0.047)
HCWS0803 0.79 (0.031)
HCWS0804 0.64 (0.025)
HCWS0805 0.51 (0.020)
HCWS0806 0.38 (0.015)
Use the table above to order adjustment washers. Replace the stock washer with
the proper combination of adjustment washers that delivers the desired clutch hit.
Hit Thickness (mm) Thickness (inch)
Softer 1.17 (0.79 + 0.38) 0.046 (0.031 + 0.015)
1.30 (0.79 + 0.51) 0.051 (0.031 + 0.020)
Stock 1.4 0.056
1.58 (1.2 + 0.38) 0.062 (0.047 + 0.015)
Harder 1.71 (1.2 + 0.51) 0.067 (0.047 + 0.020)
CAUTION:
It is easy to prematurely damage the clutch and other engine components with
improper clutch adjustment. If you are unsure of how to adjust the clutch, by even
the slightest, contact the Cobra Technical Support Group before making
adjustments.
Clutch shoe wear:
• If the clutch has been slipping and shows signs of glazing, it is best to replace
the shoes. We have found that once the shoes are glazed, even if deglazed
with emery paper or a file, the performance is reduced.
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? The best way to prevent glazing is by not gearing too high, changing the oil as
specified and by not blipping the throttle. Every time you blip the throttle, you
are working your clutch springs.
CAUTION:
The clutch produces a tremendous amount of heat and when a rider is blipping
the throttle. This makes the clutch and clutch springs wear out quicker. This also
makes your engine tend to run hotter which decreases engine power and
degrades ignition stator efficiency. It is important to train your rider NOT to be a
throttle 'blipper'.
CAUTION:
Sludge build-up between the spring washers also keeps the clutch shoe from
engaging fully and this will cause the clutch to start to slip. So you will need to
clean the sludge out or just replace the spring washers and bolts with new ones.
How quickly this sludge builds up depends on how often you change your oil
and whether your rider is a throttle ‘blipper’.
REF # DESCRIPTION
1 Crank seal
2 Clutch to hub spacer (standard 0.030” 0.76mm)
Clutch to hub spacer (thin, 0.015” 0.38mm)
3 Brass bearing
4 Clutch basket with bearing
5 Clutch Complete w/ Arbor
6 Clutch nut
Clutch arbor
Figure 25, Clutch Assembly Drawing
CLUTCH ASSEMBLY:
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INSPECTION NOTE:
1. After cleaning or replacing the spring washers, reassemble the stack up of
washers.
CAUTION:
It is important to reassemble the washer stack to that which is recommended or
to your own specialized stack.
CAUTION:
It is also important that all three shoes are stacked the same. (See figure 24)
2. Clean the threads of the stack bolt and the clutch with contact cleaner
removing all old thread locking material.
3. Apply high strength (red) thread lock material to the stack bolt and tighten to
12 ft-lb (16 N-m).
CAUTION:
Avoid allowing excess thread lock material to contact the spring washers and the
clutch or the clutch is likely to malfunction.
4. Use fine emery paper on the center hole of the clutch and on the tapered
section of the crankshaft.
5. Apply a small amount of wicking / bearing retainer (green) thread lock agent
to the center tapered section of the crankshaft and taper of clutch arbor.
CAUTION:
Lean the bike / engine such that any excess thread lock agent goes away from
the bushing in the clutch drum.
6. Put the clutch back in.
7. Apply high strength (red) thread locking agent to the threads and install the
nut and torque to 35 ft-lb (47Nm) with the special socket (see figure 25).
CAUTION:
Use high strength (red) thread locker on the threads of the clutch nut. If you are
using an impact socket, just zap it lightly with an air wrench to tighten it because
there are only about 4 threads inside the nut and they can be easily stripped. If
you are tightening it by hand, you can hold the crank from turning with the clutch
removal spanner.
Install the clutch cover tightening the bolts from inside out. (8 or 10 mm socket,
5.8 ft-lb, 7.8 Nm).
• There must be in / out play in installed clutch, 0.4mm to 1.0 mm
(0.015” to 0.040”).
• Excess in/out will cause early crank seal failure.
• A blue clutch drum is worn out from excessive slippage or improper
lubrication.
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NOTE:
To ensure proper engagement of the kick gear with the starter nut, tighten the six
screws only to the point of being not extremely loose. Using one hand rotate the
kick lever to ½ stroke and hold while tightening the six screws completely with
the other hand.
8. Fill with oil (235 ml (8.0 oz) Cobra 3 Shoe Clutch Milk.
Ignition
Stator care
Stator failure will result from running the bike hot. Following is a list of things that
will make your engine run hot.
1. The timing should not exceed the maximum specifications listed.
2. Improper carburetor jetting.
3. Improper spark plug heat range. Never run a hotter plug than the specified
spark plug.
4. Clutch slippage. See “CLUTCH” section for causes of slippage.
CAUTION:
• Because of the amount of heat generated by the clutch and engine during
extended periods of riding, it is advisable to remove the ignition cover
afterward to allow the ignition to cool off. The heat transfers through the cases
and can damage the stator as it cools off because of lack of airflow around
the stator.
• Ignition will overheat if the gap between the rotor and stator is not large
enough. There should be even clearance as the rotor rotates relative to the
stator.
• Non-resistor spark plug caps should be used. Resistor caps will result in a
weaker spark that will reduce performance.
• Make sure ground wires are secure.
• Make sure connections are free of dirt.
CAUTION:
If the engine is hot, it would be helpful to take the ignition cover off to allow
cooling.
The proper ignition timing for this model of is at 0.045” before Top Dead Center
(that means 0.045” before the piston reaches the highest point of it’s travel in the
cylinder).
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CAUTION:
Advancing the ignition timing will cause the engine to run hotter, in-turn causing
power loss, shortened clutch life, and possibly lead to premature stator failure,
and can also cause detonation which can lead to premature piston and ring
failure.
Tools recommended for timing service:
• Compact motorcycle dial indicator
• Universal clutch puller- a universal puller that pulls the clutch, main drive gear
and rotor.
TIMING YOUR IGNITION:
1. Remove the spark plug cap, and sparkplug.
2. Insert the dial indicator into the spark plug hole.
3. Remove the four bolts from the ignition cover.
4. Remove the water pump belt from the rotor and water pump shaft.
5. Turn the crankshaft counterclockwise until it reaches top dead center.
6. Set the dial indicator to zero
7. Turn the crankshaft clockwise until the dial indicator reaches 0.045” (1.14mm)
from top dead center.
8. Line up the lines on the stator and the rotor (figure 26). Otherwise loosen the
three 5mm bolts to adjust the stator.
0.045”
before
TDC
Figure 26, Lining up the line on the rotor
th the line on the stator.
wi
Figure 27, Using a dial indicator to measure piston
height for setting ignition timing.
ROTOR INSTALLATION:
1. Use wicking / bearing retainer (green) thread locker on the inside of the rotor,
and on tapered part of crankshaft.
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CAUTION:
It is recommended that you apply the proper thread locking primer to the
components that are to receive thread locking material per the manufacturers
instructions.
2. Eyeball the lines on the rotor and stator then press the rotor onto the
crankshaft firmly (figure 26).
3. Torque the nut on the rotor to 40 ft-lb (54 Nm) with high strength (red) thread
locking agent.
4. Recheck the timing following the procedure of timing your ignition.
5. Install the water pump belt back on.
6. Bolt the ignition cover back on.
7. Put the spark plug back in, and firmly stick the spark plug cap onto the spark
plug.
Cooling System
The water pump in the engine keeps the radiator fluid in circulation throughout
the motor. The air stream running through the radiator cools the radiator fluid.
Therefore dirty radiators additionally reduce the cooling effect.
Cobra has tested numerous brand name automotive and racing coolant /
antifreeze solutions and has found Liquid Performance Propylene Glycol based
Mini Coolant or Antifreeze to have the greatest effect on reducing cylinder head
temperatures.
Radiator fluid removal:
1. Remove the coolant drain plug (A) on the front of the engine case (figure 28).
A
Figure 28
To remove radiator cap:
1. Turn the cap counter clockwise to the first stop and wait there for a few seconds.
2. Push the cap down and turn it further in the same direction and remove the cap.
NOTE: Inspect the old coolant for visual evidence of corrosion and abnormal smell.
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Tools recommended for impeller service:
• Flat head screwdriver
• 13mm- hex wrench
• 3mm hex key
• 4mm hex key
• 5mm hex key
• 8mm hex key
• Propane torch
• 3/8” diameter x 8” long steel rod
• Hammer
COBRA IMPELLER SERVICE INSTRUCTIONS
1. Remove exhaust pipe and gas tank (you may be using a propane torch in step
12.
2. Remove radiator cap and drain engine coolant by removing the 13mm- hex head
coolant drain plug.
3. If the impeller is damaged or broken completely back flush the coolant system to
ensure no solid pieces are in the system.
4. Drain engine transmission oil by removing drain screw using a 13mm- hex
wrench. (item 2 in the figure below).
5. Remove right side radiator hose and unscrew coolant fitting with a 8mm hex key.
8. Remove ignition cover using a 4mm hex key (four places)
9. Stick a 3mm hex key in the water pump shaft cross hole, and remove belt
retainer screw using a 4mm hex key. (Figure 41 - item 1)
10.Remove belt retainer, water pump belt and water pump fan pulley.
11.Remove bearing retainer screw using a 3mm hex key. (Figure 29 – item 2)
Figure 29
12.Heat engine case around area of impeller lightly with a small propane torch.
Using a 3/8” diameter x 8” long steel rod, tap impeller assembly out of engine as
shown in figure 30.
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Figure 30
CAUTION:
Too much heat can be detrimental to the engine cases.
13.The shaft assembly is serviceable. Use a 4mm hex key to remove impeller
retainer screw. Remove impeller, seal and both bearings. Check shaft for wear in
the area of the seal. If there is any sign of wear (like a groove) replace the shaft.
Figure 31
14.Reinstall new bearings, seal (open side toward impeller) and impeller. Clean all
threads and use green (wicking / bearing retainer) thread locker.
15.Using a liberal amount of grease on the outside seal, bearings and inside of
case, reinstall bearing assembly by using a 0.500” ID by 1.000” OD steel tube 2”
long and tap on end of tube per figure 32.
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Figure 32
June 2006
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16.Re-assemble in reverse order of disassembly.
tainer
Temp RTV silicon or Teflon pipe sealant to the tapered pipe
Propylene Glycol based Mini
Do not mix Propylene Glycol based coolant / antifreeze solutions with Ethylene
CAUTION:
Clean all threads and use blue (medium strength) thread locker on the belt re
screw.
NOTE:
Apply Ultra black Hithreads of the coolant fitting before assembly.
NOTE:
Refill the coolant system with Liquid Performance
Coolant / Antifreeze.
CAUTION:
Glycol based coolant / antifreeze solutions.
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Fuel & Air System
Carburetor:
Tools recommended for
carburetor service:
? Small flat head screwdriver
? WD-40
? 8mm socket
Carburetor
REF. # DESCRIPTION
COMPLETE CARBURETOR 14MM
1 CARB SLIDE
2 NEEDLE
3 ATOMIZER AU 2.62
4 MAIN JET
5 PILOT JET
6 CHOKE JET
7 FLOAT
8 RUBBER CABLE CAP SEAL
9 CABLE ADJUSTOR
11 TOP CARB SCREW
12 CARB TOP
13 TOP CARB GASKET
14 SLIDE SPRING
15 NEEDLE RETAINER PLATE
16 NEEDLE CLIP
17 CHOKE ASS’Y. 2001 CM
20 FUEL MIXTURE SCREW
21 IDLE ADJUSTMENT SCREW
25 FLOAT BOWL GASKET
26 FLOAT NEEDLE
27 DIFFUSER
28 FLOAT RETAINER PIN
29 FLOAT BOWL
30
BOTTOM FLOAT SCREW
31
33 VELOCITY STACK – 04 and later
14MM CARB RESTRICTOR
Allegan Motorsports - 800-475-5660
Figure 33
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Your Cobra is equipped with an adjustable carburetor. Some fine-tuning may be
needed according to weather condition and altitude. Proper jetting is very
important for engine performance and engine life. Serious damage to the engine
can occur if not properly adjusted.
IDLE ADJUSTMENT:
On the left side of the carburetor, there are two adjustment screws. The larger
screw with the knurled head is the idle adjustment screw. To raise the idle, turn
the screw in clockwise (in 1/4 turn increments) and rev the engine after each
adjustment. To lower the idle, turn the screw counter-clockwise.
TOP END JETTING:
Indications that the engine is running too rich (too much fuel for the air) are:
• Engine not revving out or blubbering at high RPMs.
• Engine will not ‘clean out’
• Wet or black spark plug
NOTE: Before changing jetting be sure that the air filter is properly cleaned and
has the usual amount of air filter oil. An overly dirty air filter can cause the engine
to run rich.
If the engine is running rich on the top end it should be leaned out. Leaning it out
can be done by:
1. Changing the main jet to a smaller number.
2. Raising the needle clip (this lowers the jet needle) one notch at a time on the
slide.
Indications that the engine is running too lean are:
• Engine cutting out on top end.
• Engine overheating and ultimately seizure.
• White spark plug
CAUTION:
It is much safer to operate the engine slightly rich as opposed to slightly lean.
This is because an overly rich engine will just run poorly while an overly lean
engine will seize, potentially causing an expensive top end rebuild and a DNF.
To richen the carburetor:
1. Change the main jet one number at a time (larger).
2. Lower the needle clip (raising the jet needle) one notch at a time until the
engine starts to blubber on the top end, then move the clip back up one notch
or until you get the blubber out.
FUEL MIXTURE SCREW
The smaller brass screw that is towards the front of the engine is a fuel mixture
screw. This screw will also richen and lean your engine more on the bottom and
mid-range. In warmer conditions, turn the screw in. In colder conditions, turn the
screw out. Be sure to keep the carburetor very clean and make sure you don't
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have water or dirt in the carburetor bowl. Use automotive carburetor cleaner or
WD-40 to clean the carburetor inside and out.
STOCK CARBURETOR SETTINGS
The stock carburetor settings from the factory are:
• 55 pilot jet
• 92 main jet
Cleaning the carburetor:
Clean the carburetor in a well-ventilated area, and take care that there is no
spark or flame anywhere near the working area; this includes any appliance with
a pilot light. Because of the danger of highly flammable liquids, do not use
gasoline or low flash-point solvent to clean the carburetor.
1. Make sure the fuel is shut off.
2. Remove the carburetor.
3. Drain the fuel from the carburetor.
4. Disassemble the carburetor.
5. Immerse all the metal parts in a carburetor cleaning solution.
6. After the parts are cleaned, dry them with compressed air.
7. Blow out the fuel passages with compressed air.
8. Assemble the carburetor
9. Install the carburetor onto the motorcycle.
CAUTION:
1. The motorcycle will only operate
properly if the carburetor top is
installed properly with the mounting
screws, cable and choke knob
oriented as shown in figure 34.
Figure 34 Proper carburetor top
installation
rectangular
and vent elbows.
and location of
slide indexing pin
Reeds:
• The reeds must lay flat on the reed cage.
• If the reed tips aren’t lying flat, replace them immediately.
• The reeds must have a tight seal on the reed cage.
• If the reed is damaged in any way, replace it. This means cracks, chips,
and ruptures. Anything abnormal, replace the reeds.
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Take the reed cage out and hold it up to the light and look in through the cage. If
you see light between the reed pedals and the frame, then replace the reeds. If
you do not see light, then the reeds should be ok. (See figure 35)
Figure 35
The presence of light indicates that the reeds should be replaced, or possibly turned over.
Exhaust
The pipe is a crucial element to a motorcycle. Any kinks, dents, or damage done
to the pipe will result in a major performance loss.
NOTE:
Be sure to take the pipe off, and any carbon that may be built up. Carbon build
up is created from exhaust. Exhaust has oils in it, and the oils cling to the walls
of the inside of the pipe. Over a long period of time, the diameter of the pipe will
decrease, due to carbon build up. So it is essential to clear the residue.
CAUTION:
It is important to repack the silencer. Signs of your silencer needing to be
repacked are:
• The bike is louder than normal.
• A loss of power.
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Wheels & Tires
Rear wheel pullers
Disassembly:
Figure 36
Rear wheel alignment:
1. Remove axle, and
back wheel assembly.
2. Pull the rear wheel
pullers out of the back
of the swing arm.
Either
• Accurately measure the distance from the swingarm pivot to the axle center
on each side or
• From the rear of the bike, sight up through both sprockets to ensure that the
chain is running in a straight line (no bend in between or jog at either
sprocket).
Tuning
Suspension
Adjustment:
1. Front forks
1.1. Fork oil
1.1.1. Oil type
1.1.1.1. Heavier weight oil – more damping – slower responding
1.1.1.2. Lighter weight oil – less damping – quicker responding
1.1.2. Oil quantity / level
1.1.2.1. Greater quantity / higher level – greater bottoming
resistance, stiffer near the end of the travel.
1.1.2.2. Smaller quantity / lower level – less bottoming resistance,
less stiff near the end of the travel.
1.2. Fork spring (optional spring)
1.2.1. Stiffer spring (higher spring rate) – stiffer throughout the travel.
1.2.2. Less stiff spring (lower spring rate) – less stiff throughout the travel.
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1.3. Fork height
1.3.1. Rise in clamps for quicker turning.
1.3.2. Lower in clamps for improved straight line stability.
2. Rear shock
2.1. Shock spring (optional spring)
2.1.1. Stiffer spring – stiffer throughout the travel.
2.1.2. Less stiff spring – less stiff throughout the travel.
2.2. Compression damping (optional valve)
2.2.1. Harder (more damping, slower) – adds resistance to the
suspension motion when the suspension is compressing.
2.2.2. Softer (less damping, quicker) – reduces resistance to the
suspension motion when the suspension is compressing.
2.3. Rebound damping (optional valve)
2.3.1. Harder (more damping, slower) – adds resistance to the
suspension motion when the suspension is returning to full length.
2.3.2. Softer (less damping, quicker) - reduces resistance to the
suspension motion when the suspension is returning to full length
Front Forks Bottoming Too Frequently Fork oil level
If the front forks bottom harshly more than a couple of times per lap and the fork
springs are proper for the weight of rider (as detailed above), try raising the fork
oil level in increments of 10mm. Raising the fork oil level, reduces the air volume,
and increases the stiffness of the forks late in the travel, thus adding a
progressive’ feel.
Front forks feel too stiff over small bumps. Fork oil weight
If the forks feel too stiff over small bumps try decreasing the weight (increasing
the viscosity) of the fork oil.
Rear suspension troubleshooting. Damping
Always start with standard settings and make damping changes in no more than
two click increments and only make one change at a time.
Symptom Action
Rear end feels stiff on small bumps Softer compression damping
Rear end ‘sways’ on straights Harder compression damping
Bike tends to jump ‘rear end high’ Harder rebound damping
Bike tends to jump ‘rear end low’ Softer rebound damping
Frequent rear end bottoming Harder compression damping
Bottoms after end of continuous bumps Softer rebound damping
Rear end ‘kicks’ over square edge bumps 1) Harder rebound, 2) Softer
Compression
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Proactive Suspension Adjustments
Once you have the suspension adjusted for decent overall feel, you can make
proactive adjustments when faced with different racing conditions.
Situation Actions
Sand track Lower the rear end (increase race sag).
Sand track Stiffer compression and rebound damping.
Long fast track Lower the forks in the clamps by 3 mm.
Tight slow track Raise the forks in the clamps by 3 mm.
Mud track Lower the bike if the rider has difficulties
touching the ground.
Rear shock
The rear shock on your Cobra is adjustable to your riders weight and riding style
by changing the spring rate (stiffness) of the spring and / or by changing the
damping valves.
Due to the complexities of the shock absorber internals, Cobra recommends that
you either send the shock back to us for damping valve changes or send the
shock to a competent suspension specialist such as PR2.
Cobra offers stiffer and softer shock springs depending on the weight of your
rider. See the Parts Shock section or the Optional component section at the
beginning of the manual for these other components.
Front Forks
Cobra offers stiffer and softer fork springs depending on the weight of your rider.
See the Parts Shock section or the Optional component section at the beginning
of the manual for these other components.
The front forks are designed with the damping components in separate fork legs.
The compression damping duties are performed in the right fork leg and the
rebound damping duties are performed in the left fork leg. This allows easy
adjustment of the damping characteristics by appropriately changing the viscosity
of the fork oil in the fork leg controlling the damping characteristic that needs
changed.
Example: if stiffer compression damping is required, switch from 20 (standard)
weight fork oil to 25 or 30 weight oil in the right leg. If softer rebound damping is
desired, switch from 20 (standard) to 15 or 10 weight fork oil in the left leg.
NOTE:
Fork oil level affects bottoming harshness, and oil viscosity affects valving speed.
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Gearing
For a bike with a centrifugal clutch, it’s better to be geared too low than too
high.
What happens with improper gearing?
• Poor performance
• Not enough top end speed
• No snap
• Over heat clutch
• Premature failure of engine seals, bearings, & electronics
• High clutch wear
Condition Gear Taller Gear Lower
Mud
Sand
Hills
Hard Pack
Throttle Blipper (novice)*
*It may be helpful to set up the clutch to hit early for smooth power delivery
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Rear
Ratio Write © Cobra R&D
Front Sprocket
15 33 2.20
15 34 2.27
15 35 2.33
14 33 2.36
15 36 2.40
14 34 2.43
15 37 2.47
14 35 2.50
15 38 2.53
13 33 2.54
14 36 2.57
15 39 2.60
13 34 2.62
14 37 2.64
15 40 2.67
13 35 2.69
14 stock 38 2.71
15 41 2.73
13 36 2.77
14 39 2.79
15 42 2.80
13 37 2.85
14 40 2.86
13 38 2.92
14 41 2.93
13 39 3.00
14 42 3.00
13 40 3.08
13 41 3.15
13 42 3.23
Sprocket
Gear Ratio
2004
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Carburetion
Although your Cobra is sent from the factory with the carburetor jetted for optimal
performance, you may find it necessary to adjustment your particular jetting due
to current weather conditions, altitude, fuel variations, and/or engine
modifications.
CAUTION:
Proper jetting is very important for engine performance and engine life.
Symptoms of improper jetting are listed below.
• Symptoms of incorrect oil or oil / fuel ratio
o Poor acceleration
o Misfire at low engine speeds
o Excessive smoke
o Spark plug fouling
o Excessive black oil dripping from exhaust system
• Symptoms of too rich a fuel mixture
o Poor acceleration
o Engine will not ‘rev’ out, blubbers on top
o Misfire at low engine speeds
o Excessive smoke
o Spark plug fouling
o Wet, black, or overly dark spark plug (when removed for inspection)
• Symptoms of too lean a fuel mixture
o Pinging or rattling
o Erratic acceleration
o Same actions as running out of fuel
o High engine temperature
o White spark plug (when removed for inspection)
NOTE:
When inspecting the spark plug to evaluate jetting, a properly jetted machine will
produce a spark plug that is dry and light tan in color.
Environmental and altitude related mixture adjustments
Condition Mixture will be Required adjustment
Cold air Leaner Richer
Warm air Richer Leaner
Dry air Leaner Richer
Very humid air Richer Leaner
Low altitude Standard None
High altitude Richer Leaner
Low barometric pressure Richer Leaner
High barometric pressure Leaner Richer
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NOTE:
• Before making any carburetor jetting changes verify that:
o You are using the proper fuel and oil
o The fuel is fresh and uncontaminated
o The oil and fuel have been mixed in the proper ratio
o The carburetor is clean (no plugged jets)
o The air filter is properly clean and oiled
o The float height is within proper specification (proper measuring technique
is described later in this section)
NOTE:
Perform all jetting changes on a motorcycle that has been warmed up to proper
operating temperature.
The carburetor on your Cobra motorcycle is quite adjustable. Figure 59 shows
its range of adjustment and in particular what adjustable component affects what
range of operation (specifically throttle position).
Figure 59
FUEL SCREW ADJUSTMENT: Adjust for maximum idle speed
The fuel adjustment screw is located on the left side of the carburetor. It is the
smaller of the two adjustment screws and requires the use of a small flat blade
screwdriver for adjustment. After adjusting for maximum idle speed, use the idle
screw to adjust the desired idle speed.
NOTE:
If the fuel screw requires more than 3 turns out, replace the pilot jet for one that is
one size richer (larger number) then re-adjust the fuel screw.
IDLE ADJUSTMENT: Adjust for desired idle speed
The idle speed screw is located on the left side of the carburetor. It is the larger
of the two screws on the side of the carburetor and is unique with its knurled
head for easy fingertip adjustment. To raise the idle, turn the screw in, clockwise,
(in 1/4 turn increments) and rev the engine after each adjustment. To lower the
idle, turn the screw counter-clockwise.
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TOP END JETTING: Adjust for clean full throttle acceleration
Jet your top end (main jet) based on the acceleration of your Cobra Motorcycle
on the longest straight at the track. Observe any of the lean or rich symptoms
(spark plug appearance and bike performance) listed above and change your
jetting accordingly.
PART THROTTLE Adjust for desired acceleration
Using an area of the track that allows the rider to operate and mid throttle and
transition (accelerate, or ‘roll on’) from closed, or mostly closed throttle, to a
larger throttle opening. Observe the rich and lean symptoms listed above.
Adjust the jet needle position by moving the clip from its current position (move
the clip higher on the needle to make the bike run leaner, or move the clip lower
on the needle to make the bike run richer) to one higher or lower.
Troubleshooting
1) Engine not behaving properly
a) Carburetor top is installed backwards (happens a lot)
b) The carburetor slide indexing pin is missing
c) Wrong spark plug installed (8339 Champion to be used on ’04 or later & no
)
mods
d) Needle clip is on top of plastic not below
e) Air leak – find where with carb cleaner or similar
f) Ground wire or ignition leads have fault
2) Engine is down on power
a) Clutch engagement is not set properly
b) Jetting is incorrect
c) Silencer needs repacked
d) Exhaust pipe
i) Has excess carbon buildup
) Has large dent in it
ii
e) Compression is low
i) Piston
) Rings
ii
f) Reeds are damaged
g) Ignition timing is incorrect
3) Engine is excessively loud
a) Silencer needs to be repacked
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4) Engine cuts out at high RPMs
a) Stator bad
b) Carburetor diffuser plate upside down (install like a skirt)
c) Plugged fuel petcock
d) Silencer core tube broken
5) Engine won’t start
a) Fuel
i) None in tank
) Is sour or bad
ii
b) Carburetor is dirty
c) Ignition
i) Spark plug fouled
) Wrong spark plug installed (8339 Champion to be used on ’04 or later & no
ii
)
mods
) Spark plug cap off
iii
) Engine Shut-off ‘kill’ switch is shorted
iv
v) Bad electrical ground
) Stator winding damaged
vi
d) Exhaust is plugged
6) Overheating
a) Bad stator
b) Water pump pulleys or belt broken
c) Water pump impeller broken or bolt out
d) Jetting too lean
e) Too much throttle blipping
f) Too
g) Kinked radiator hose
h) Rear brake dragging
i) Chain too tight
j) Air leak
7) Engine won’t idle
a) Idle knob needs adjusted
high gearing
b) Air leak
c) Carburetor jets are dirty
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