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 CX50JR 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.
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.
CAUTION:
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.
MCCJ2015.0
Page 2
Table of Contents
General Information ........................................................................................................ 4
Specifications - General .............................................................................................. 4
Index ............................................................................................................................ 78
3
Page 4
GeneralInformation
Items
Premix oil ratio after break
Slow (Pilot) Jet / Main Jet
Transmission / clutch oil type
Rear Shock ( std settings)
CX50 JR
coolant / distilled water
0.040” (1.0 mm) Before Top Dead Center(BTDC)
(20 psi for hard pack or rockyconditions)
CARD 32mm USD Fully Adjustable w/SmartLeg
rebound11/2
Compression Low 7, High 7, No ReboundAdj.
Specifications
Dimensions
Wheelbase
Wheel size
Seat height
Engine
Type
Cooling system
Coolant
Displacement
Bore and stroke
Ignition system
Spark plug
Gap
Ignition timing
Fuel type
Premix Oil type
Carburetion
Float Height
Transmission
Speed / Clutch
Final drive ratio
Chain
Quantity
Chassis
Front tire
Pressure
Rear tire
Pressure
Front fork
Fork oil type
Fork oil amount
Std settings
- General
35.75” (908mm)
10” (254mm)
23.9” (607 mm)
2-stroke, single cylinder, reed valve
Liquid-cooled
50/50 antifreeze-
49.8 cc
39 mm x 41.7 mm
Electronic, analogic advance
Autolite - XS61 & 4261
0.023” – 0.025” (0.58 – 0.64 mm)
High octane pump gasoline
Bel-Ray H1-R
-in 40:1 to 50:1
14 mm Dell’Orto
55 / 92
16mm + 0.5mm (0.63” + 0.020”)
Single / Cobra 3 shoe
14/37 T
420
Cobra Venom 3 Shoe Clutch Milk
235 – 350 ml (8 – 12oz)
2.50 – 10
15 psi minimum
2.75 – 10
15 psi min.
2.5wt Bel-Ray Fork Oil
145 ml
Smart leg: 3out,Compression and
out
4
Page 5
Optional Suspension Components
Weight of Rider (lb) Fork Spring Shock Spring
Less than 38 (light)
38 – 45 (std)
46 to 55 (stiff)
KCCJ3218
(18 lb/in, 3.15 N/mm)
KCCJ3221
(21 lb/in, 3.70 N/mm)
KCCJ3225
(25 lb/in, 4.40 N/mm)
SCMUOH04 (275 lb/in) red
SCMUOH05 (285 lb/in)
yellow
SCMUOH06 (295 lb/in)
white
Specifications - Torque Values
Fastener
Cylinder head nuts 10.3 123 14 M7 X 1.0
Crankcase bolts 8.8 105 12 M6 x 1.0
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 bolts 5.8 70 7.9 M6 X 1.0
Torque Value
Size & Remarks
ft-lb in-lb Nm
Clutch nut 40 480 54 10 x 1.25*
Clutch bolts 12 144 16 M6 x 1.0*
Engine mount bolts 22 265 30 M8 X 1.25
Swingarm pivot 21 250 28 M14 X 2.0
Shock bolt 35 420 47 M10 x 1.5**
Triple clamp (top) 12 144 16 M8 x 1.25
Triple clamp (bottom) 6 72 8 M6 x 1.0
Water pump impeller 3.6 44 5 M5 x 0.8*
Intake manifold bolts 4.6 55 6.2 M6 X 1.0
Ignition rotor nut 33 400 45 M10 x 1.25**
Rear sprocket bolts 16 195 22 M7 X 1.0**
Axle nuts 25 300 34 M12 X 1.25
* Apply high strength thread locking agent when installing.
**Apply medium strength thread locking agent when installing.
(SP) To apply the proper torque to the spark plug when inserting, first screw the
spark plug in until the metal gasket ring causes resistance and then turn another
¼ turn.
5
Page 6
Break-In Procedure
Your Cobra CX50 JR is a close-tolerance high performance machine and breakin time is very important for maximum life and performance. The CX50 JR can be
ridden hard after the first ½ hour break-in time.
Cobra recommends Bel-Ray H1-R premix oil with high octane
pump gas mixed at 40:1 (150 ml oil to 2 gallons of gas). Other
brands of oil should be mixed at 32:1 for break-in.
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.
• Allow bike to cool and inspect bike for loose fasteners.
• Avoid prolonged operation at Wide Open Throttle for the next half hour.
• After 1 hour of operation
o Check for loose bolts and nuts.
o Clean the carburetor bowl.
o Change the transmission / clutch lubricant.
• Check CFD torque and adjust as necessary
• After 8 hours of operation
o Change the fork oil.
o Have a Certified Cobra Mechanic or suspension specialist 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) 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.
Never remove the radiator cap of a machine that has a warm engine. Burning
and scalding could occur.
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Page 7
Starting Procedure
Before starting the machine inspect the following:
• Tire pressure
• Chain tension
• Coolant level
• Proper wear on chain rollers and sliders
• Handlebar tightness
• Throttle assembly movement/cable adjustment
• Air Filter
• Check for loose nuts and bolts
• Turn the fuel on by rotating the fuel petcock knob to the vertically downward
position (reserve position is horizontally forward)
NOTE: For best results from your Cobra Motorcycle use only the recommended
fuel. Testing has shown that most ‘race’ fuels actually degrade performance.
Always wear a helmet and other protective riding gear.
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 until the engine is at operating temperature.
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.
CAUTION:
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.
CAUTION:
Make sure your riders’ foot is not resting on the foot brake while they are riding
7
.
Page 8
Maintenance
A properly maintained machine is safer, faster, and more fun to ride. It is
important that you adhere to this maintenance schedule so as to promote the
longevity of your Cobra Motorcycle
Tips
1. Recommended lubricants:
a. Cobra Clutch Milk is by far the best auto clutch lubricant. It is a
full synthetic lubricant that has been specifically formulated for
Cobra’s auto clutch and has;
• Exceptional film strength over petroleum based oils or
synthetic blends.
• Extreme temperature tolerance.
• NO frictional modifiers.
• Dispersant package to keep clutch fibers in suspension so
they can be flushed out when the oil is changed.
• Extremely low viscosity for minimal drag and ‘windage’.
b. Bel-Ray H1-R oil is the recommended premix oil because:
• Its Ester base leaves a film on all parts at all times. No metal
to metal startups or corrosion potential.
• Exception film strength over petroleum based oils or other
synthetic blends.
• Easily atomizes and burns completely.
• Does not fall out of suspension from premix in cold weather.
• Produces virtually no coking deposits, leaving pistons, rings
and heads extremely clean with minimal pipe ‘spooge’.
2. Filling your transmission with more than 8.0 oz (235 cc) of lubricant will help
to transfer heat from the clutch. Filling with more than 12 oz (295 cc) will
degrade performance.
3. The cylinder base gasket has been ‘fitted’ for your engine. The code
number stamped into the engine cases will guide you to what thickness
base gasket is required during a common top end service. See the service
section of this manual to correspond a code number with a base gasket part
number.
4. Evaluate the bikes jetting only after it has been warmed up to race
temperatures.
5. New chains will stretch on first use. Never install a new chain prior to a
race. Always ‘break’ them in during practice.
6. 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). Example, CMxxxx7xxx is a 2007 MY CX50 JR.
7. 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.
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Page 9
8. 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.
Be sure the fuel tank and carburetor have been removed and safely located
away from the welding process.
9. 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. Use ER70S6
filler if welding on the frame.
10. 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
11. Inspect CFD slip torque after the 2
After this follow the recommended schedule below.
12. Check proper clutch engagement before and after each ride. If the clutch is
engaging properly DO NOT feel the need to take the clutch apart to;
measure the spring stack, clean the stack, replace the springs, etc... Cobra
has worked very hard to make a clutch that is low maintenance and so only
take it apart if it NEEDS to be maintained.
nd
ride and then again after the 6th ride.
Schedule
• Prior to each ride
o Check that the air filter is cleaned and oiled.
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.
o Check for adequate tire pressure.
o Check all nuts and bolts for proper torque.
o Spray all moving parts with WD40 or other light oil.
o Check drive chain for
Proper tension.
Adequate lubrication.
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 its safe limits.
o Check the rims for signs of stress, like cracks around the rim, spokes
and hub.
o Equalize the pressure in the forks with atmosphere.
•Every 2 hours of operation
o Replace the transmission oil.
o Check the CFD torque
• Every 10 hours of operation
o Replace the fork oil.
o Have the shock oil replaced by a Certified Cobra Mechanic.
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Page 10
Replacing Transmission / Clutch Lubricant
Tools needed:
• 5mm allen wrench
• Minimum of 235 ml (8 oz) Cobra Venom 3 Shoe Clutch Milk (Part
#MCMUGF32).
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. Remove the oil drain plug, on the clutch cover, near the brake lever (figure 1).
Figure 1
3. Allow the oil to drain completely, then reinstall the oil drain plug.
4. Remove the oil fill plug and add 8.0oz of Cobra Venom 3 Shoe Clutch Milk
thru the oil fill plug.
NOTE: Putting additional oil, up to 350 ml (12 oz), can help clutch life. More than
350 ml (12 oz) will degrade engine performance.
NOTE: It can be helpful to lean the bike over on its left side to add oil to the bike.
5. Reinstall the oil fill plug.
NOTE: 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
lubrication and cooling capability over extended periods of time and is the
recommended lubricant for your Cobra motorcycle.
(Part # MCMUGF32) was formulated to provide superior
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Page 11
Proper 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.
A properly adjusted chain will have
50mm (2”) free movement behind the
chain block with no load on the bike.
(figure 2)
3.
Sit on the bike and verify that the chain has a
minimum of 12mm (1/2”) free movement when the
chain is at its tightest point.
4. 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).
5. Retighten the axel bolt to 25 ft-lb (34 Nm).
6. Retighten the adjustor bolt
Figure 2
Rear Brake Maintenance
CAUTION:
Too little brake pedal free-play will allow the brake pads to drag causing the pads
to wear prematurely and possible engine component failures. Too much free-play
will not allow the rider to apply the brakes quickly.
1. Set pedal height/position first, then
2. Set pedal free play.
Brake pedal height can be adjusted with the bolt and nut located under the rear
of the brake pedal. The free-play is adjusted with the adjustable plunger on the
end of the brake pedal.
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CAUTION:
Use only DOT 4 brake fluid
Setting rear brake pedal position (see figure 2b):
1. Loosen the lock nut (10mm wrench).
2. Adjust the brake lever stop (10mm wrench) so that the lever is comfortably
reachable in both:
a. Standing riding position, and Figure 2b
b. Sitting riding position.
3. Tighten the lock nut (10 mm
wrench).
CAUTION:
Adequate pedal free play is required
so that the brake pads do not drag on
the rotor. 1” MINIMUM.
Make sure that the free play locking
clip is installed such that one must
push forward, toward the front of the
bike, to remove. Otherwise the clip is
apt to come undone while riding.
To adjust (see figure 2b):
1. Loosen the lock nut (10mm).
2. Undo the free play locking clip from around the brake adjustor (plunger),
with your hand by pushing it forward.
3. Slide the pin of the locking free play locking clip from the brake lever
4. Adjust as needed by rotating the clevis on the end of the adjustor
(plunger).
NOTE: Turning the clevis Clockwise will lengthen the adjustor (plunger),
removing free play from the system, and turning the clevis Counter-Clockwise will
shorten the adjustor (plunger) adding free play to the system.
• Attach the syringe to the brake caliper bleed access. Keep the syringe
oriented as not to allow air from the syringe into the system.
• Using the syringe pull fluid through the system. Use caution not to let the
fluid in the reservoir to become low and introduce air into the system.
• Using the syringe push fluid back into the system until the reservoir is full.
• Repeat these actions of pulling and pushing fluid through the system a few
times.
• With the reservoir full, engage the brake lever/pedal and hold it there as if
engaging the brakes.
• While doing this pull on the plunger of the syringe. Doing this will cause a
vacuum in the system. The vacuum will swell the air bubbles which assist
in them moving throughout the system.
• Continue pulling a vacuum and release the brake lever/pedal (careful not
to allow the reservoir to become empty).
• Once again engage the brakes while continuing to pull a vacuum.
• When the reservoir is almost empty stop and push fluid back into the
system.
• Repeat these steps with the vacuum until no more air bubbles can be
removed from the system.
• Remove the syringe. Be sure to keep the caliper below the level of the
reservoir to allow the fluid to run out of the caliper and not allowing air into
the system.
• Reinstall the bleed screw, being sure that the ring is in place.
• Fill the reservoir with fluid (the fluid should be full enough that the fluid
spills out when placing the lid on) and replace the cover.
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Page 14
Air Filter Cleaning
Tools recommended for air filter maintenance:
• #2 Phillips head screwdriver
• 4 mm Allen wrench
• Foam filter oil
Procedure
1. Removed the seat with a 4 mm Allen wrench.
2. Remove the filter/air inlet boot from the back of the carburetor with a Phillips
screwdriver
3. Pull the filter / boot assembly out the top of the air box.
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.
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 waterresistant 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 making sure the letters “CM” are visible
between the carburetor and air box (figure 4).
Figure 4
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.
14
Page 15
Fork Maintenance
Cobra strongly recommends that a professional service technician conduct all
internal maintenance other than changing springs and oil. This will help to ensure
safe and consistent operation.
For routine maintenance, the chart below provides suggested service intervals
for common procedures:
Each Ride
Bleed excess air X
Change Oil X
Change
Seal/Swiper
Change Bushings X
Fork Air Bleeding
Tools required
• 3mm hex key (Allen wrench)
During normal operation, both fork legs will build up air pressure. This pressure
acts as an additional spring so it must be bled on a regular basis to maintain
consistent suspension operation. Before each ride, loosen the socket head cap
screw located at the front of each fork cap far enough so that any excess
pressure in the leg is relieved. After excess air is bled off, retighten the screw to 5
in-lb. Be careful not to lose or damage the sealing ring that is located under the
head of each bleed screw.
10 hours 20 hours As Needed
X
Fork Oil Replacement
Tools required
• 32mm Fork Cap Tool (MCMUTL32)
• 19mm wrench or socket
• 4 & 5 mm hex key (Allen wrench)
• 9/16 wrench
• Mallet
• 2.5 wt. Bel-Ray fork oil
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Page 16
Disassembly procedure
1. Remove the front wheel (19 mm wrench).
2. Remove the brake caliper from the fork leg (4 mm hex key).
3. Loosen the fork caps (32mm fork cap tool).
4. Remove the fork legs from the triple clamps (5 mm hex key).
5. One leg at a time
a. Remove the fork cap from the fork tube.
b. Pull the fork spring down to gain access to the fork cap jam nut and
secure it with a 9/16 wrench.
c. Holding in one hand the 9/16 wrench use the fork cap wrench to
unscrew the fork cap from the damper rod.
d. Remove the fork spring pad, and fork spring.
e. Inside the damper rod, the rebound adjustment screw pin is resting
and will fall out of the damper rod when the fork is inverted. Try to
catch it before it falls into your oil bucket.
f. Invert the fork and allow the oil to drain completely. Working the
damper rod up and down will speed up the draining process.
Assembly procedure
1. Fill the fork with 145ml of fork oil.
2. Work the damper rod up and down to allow the fork cartridge to fill with oil.
3. Install the rebound adjustment screw pin into the damper rod.
4. Install the fork spring and spring pad.
5. Extend the damper rod completely and Compress the fork spring enough to
begin threading the fork cap back onto the damper rod.
6. Make sure that the fork cap threads onto the damper rod completely before it
makes contact with the jamnut.
7. Tighten the jamnut.
8. Tighten the fork cap to the fork leg outer
9. Pump the fork leg several times to verify that it operates smoothly.
10. Install each leg back into the triple clamp. Torque each pinch bolt to 8N-m (6
ft-lb) making sure both legs are set to the same height in the clamps.
11. Reinstall the brake caliper.
12. Reinstall the front wheel (25 ft-lb, 34 Nm).
Cobra Frictional Drive (V3 CFD)
The Cobra Frictional Drive (CFD) is essentially an adjustable slip clutch that
dissipates torque spikes transmitted from the rear wheel to the rest of the drive
line and engine. Instead of these torque spikes potentially damaging internal
components, the CFD allows the transmission to slip with respect to the engine.
For this to occur, the CFD must function properly by ‘slipping’ above a minimum
torque value.
The safe minimum slip torque of the CFD should be checked every 2 hours of
operation, after break-in.
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Page 17
The slip torque value should be above 60 ft-lb (81 Nm) measured at the sprocket.
To properly measure the minimum torque at which the CFD (Cobra
Frictional Drive) slips
1. Access the slip clutch by draining the oil and removing
the cover exposing the CFD.
2. Brace the CFD gear from turning with a suitable device
(Cobra tool EAMU0004 or similar).
3. Install the Sprocket Socket CFD torque checking tool
(MCMUTL15) on the sprocket and secure with the
supplied screw and ensure that the tool is completely
up against the sprocket
4. Verify with a torque wrench applied to the Sprocket
Socket that the V3 CFD does not slip below 81 Nm (60
ft-lb) in either direction.
5. If there is slippage below 81 Nm (60 ft-lb)
remove the cotter pin and tighten the castle
nut on the CFD one more position (it is a left
hand thread nut so you must turn it
counter clockwise)
CAUTION:
Do not check earlier versions of the CFD with this method! The torque valves
required at the sprocket would be much higher
HINT:
This V3 CFD torque checking method is possible do to with the chain on. Just put
the bike on a stand so that the rear wheel can turn freely.
HINT:
The CFD hubs can be removed with the universal puller (MCMUTL70).
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Page 18
Parts
REF #
PART #
DESCRIPTION
Parts – Airbox and Inlet System
Airbox and Inlet System
1 ZCCS0001 GASKET – REED TO CYLINDER
2 ECMU0246 REED CAGE ASSEMBLY WITH REEDS VFORCE
3 RCCS0002 INLET MANIFOLD
4 HCWF0601 6mm FLAT WASHER
5 HCBC0603 M6X30mm SOCKET HEAD CAP SCREW
6 MCKGHO04 HOSE CLAMP – CARBURETOR TO MANIFOLD
7 RCCM0001 CARBURETOR 14mm
8 RCCM1301 VELOCITY STACK
9 MCKGHO01 HOSE CLAMP – AIR BOOT TO CARBURETOR
10 RCCJ0004 AIR FILTER WITH BOOT
11 RCMU0405 AIR BOX - JR
12 TCCJ0004 MUD FLAP
13 HCBB0612 M6X12mm BUTTON HEAD BOLT (2 REQ’D)
14 RCMU1407 BRACKET – MUD FLAP
15 ECCS0030 REEDS REPLACEMENT KIT
16 FCMU0026 FUEL LINE 5” (NOT SHOWN)
17 MCMUCL04 HOSE CLAMPS – FUEL LINE (NOT SHOWN)
18 RCMU0022 VENT HOSE (NOT SHOWN)
18
Page 19
Parts – Bars and Controls
REF #
PART #
DESCRIPTION
Bars and Controls
1 FAMU0013 HANDLEBAR - ALUMINUM
2 TCMU0008 GRIPS (SET OF TWO) – SCOTT WAFFLE
3 FCMU0066 THROTTLE ASSEMBLY
4 FCPW0004 CABLE COVER
5 FCMU0021 THROTTLE COVER
6 FCMU0019 THROTTLE CABLE
7 BAKG0003 BRAKE ASSEMBLY FRONT
8 FCMU0033 KILL SWITCH ASSEMBLY
9 HCBC0803 M8X30mm SOCKET HEAD CAP SCREW (4) REQ’D
10 HCBC0825 M8X25mm SOCKET HEAD CAP SCREW (4) REQ’D
11 TKMU0404 BAR MOUNT KIT, SHORT (1 REQ’D) STANDARD
1 EKMU0011 WATER PUMP KIT WITH IMPELLER
2 ECKG0142 SHAFT, WATER PUMP
3 ECKG0072 BEARING, WATER PUMP
4 ECKG0074 SEAL, WATER PUMP SHAFT
5 ECKG0073 IMPELLER, WATER PUMP (ALUMINUM)
6 HCBC1512 M5X12mm SOCKET HEAD CAP SCREW (STAINLESS)
7 ECMU0167 BEARING –WATER PUMP BIG
8 ECKG0175 WATER PUMP PULLEY, FAN TYPE – DRIVEN
9 ECMU0180 BELT RETAINER
10 HCBS0003 SHOULDER BOLT 6mm
11 ECKG0170 WATER PUMP BELT
12 ECKG0042 WATER PUMP PULLEY, CRANK
13 HCNS1001 M10 NUT
14 HCBC0408 M4X8mm SOCKET HEAD CAP SCREW (BLACK OXIDE)
15 HCWF0401 4mm WASHER
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Parts – Engine – Top End
REF #
PART #
DESCRIPTION
Engine – Top End
1 ECCJ0001 CYLINDER (INCLUDES PISTON, RINGS, PIN & CLIPS)
2 ZCMU0011 BASE GASKET (0.25mm) THICK
2 ZCMU0703 BASE GASKET (0.30mm) THICK
2 ZCKG0501 BASE GASKET (0.40mm) THICK (STANDARD)
2 ZCMU0705 BASE GASKET (0.50mm) THICK
2 ZCMU0706 BASE GASKET (0.60mm) THICK
2 ZCMU0708 BASE GASKET (0.80mm) THICK
3 ECMU0060A PISTON KIT – ‘A’ SIZE
3 ECMU0060B PISTON KIT – ‘B’ SIZE
3 ECMU0060C PISTON KIT – ‘C’ SIZE
3 ECMU0060D PISTON KIT – ‘D’ SIZE
4 ZCMOTE11 O-RINGS – PIPE TO FLANGE (2 REQ’D)
5 ECMU0155 PISTON RINGS (2 PER SET)
6 ECMUSR00 SNAP RING FOR PISTON (2 PER SET)
7 ECKG0012 WRIST PIN
8 ECMU0077 BEARING, WRIST PIN
1 KACJ0001 FORK ASSEMBLY FORK LEGS ONLY
2 KCMU0011 FORK GUARD SET
3 TCC60019 WASHER FORK GUARD (4 REQ’D)
4 HCBC0601 M6X16mm, SOCKET HEAD CAP SCREW (4 REQ’D)
5 BCC60015 BRAKELINE CLAMP
6 HCBC0612 M6X12mm, SOCKET HEAD CAP SCREW (2 REQ’D)
7 HCNL0601 M6 LOCKNUT (2 REQ’D)
8 FACJ0004 TRIPLE CLAMP BOTTOM ASSY JR (CLAMP & STEERING STEM)
9 FCCJ2005 TRIPLE CLAMP TOP JR
10 HCNJ0102 JAM NUT STEERING STEM (2 REQ’D)
11 HCBC0806 M8X30mm SOCKET HEAD CAP SCREW (4 REQ’D)
12 HCBC0820 M8X20mm SOCKET HEAD CAP SCREW (4 REQ’D)
13 TKMU0404 HANDLE BAR CLAMP KIT SHORT (STANDARD)
13A TKMU0403 HANDLE BAR CLAMP KIT TALL
14 FCMU1103 DUST COVER (2 REQ’D)
15 SCMU0036 O-RING (2 REQ’D)
16 FCMU0023 SPACER (2 REQ’D)
17 FCMU0024 SEAL (2 REQ’D)
18 FCMU0004 STEERING HEAD BEARING (2 REQ’D)
19 HCBC0625 M6X25mm SOCKET HEAD CAP SCREW (4 REQ’D)
20 HCBF0616 M6X16mm FLANGED HEAD W/8mm HEX
21 HCBC0825 M8X25mm SHCS (4 REQ’D)
22 FCMU0011 STEERING HEAD RACE (2REQ’D)
ACCESSORY
FKMU0003 KIT – STEERING STEM BEARINGS, RACES AND SEALS
29
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Parts – Forks – Leg Assembly – Brake Side
30
Page 31
REF #
PART #
DESCRIPTION
1
2
3
4
5
6
7
8
9
10
11
12
13
14
14
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
37
HCBC0408 4 X 8 SHCS CLEAR ZINC
ZCKG0001 GASKET, BLEED SCREW FORK
KCCS0004C FORK CAP - CONVENTIONAL 32MM USD
ZCMUOR18 O-RING – 3mm x 27mm ID
KCCS0036 FORK - SPRING WEAR PLATE 32MM
KCCS0005 FORK - OUTER TUBE 32MM
KCCS0035 RING CLIP FORK OUTER WEAR RING 32MM
KCCS0006 FORK GLIDE RING BOTTOM 32MM
KCCS0032 FORK SEAL SPACER 32MM
KKCS0004 FORK SEAL AND SWIPER KIT 32MM
KCCS0002 RING CLIP - FORK SEAL RETAINER - 32MM
KCC60067 FORK JOUNCE BUMPER
KCCS0013 FORK SPRING GUIDE 32MM
KCCJ3221 STANDARD SPRING - FORK 0.21 KG/MM 32mm
KCCj3218 LIGHT SPRING - FORK 0.18 KG/MM 32mm
KCCJ3225 HEAVY SPRING - FORK 0.25 KG/MM 32mm
HCNJ3824 NUT JAM 3/8-24 CLASS 8
KCC60068 RING CLIP - FORK SPRING GUIDE RETAINER
KAC60003 DAMPER ROD ASSEMBLY
KCC60058 O-RING MID-VALVE ADJ NEEDLE
KCC60050 FORK MID-VALVE ADJUSTER NEEDLE
KCC60051 SPRING - FORK ADJUSTER NEEDLE
KCCS0018 GLIDE RING - FORK PISTON - MID VALVE
HCNJ0601 6MM JAM NUT
BCKG0033 O-RING – 2MM ID
KCCS0033 ADJUSTER SCREW TOP 32MM
KCC60049 ADJUSTER PIN
KCMU0013 CARTRIDGE CAP
KCKG0050 TOP OUT SPRING
KCCJ0002 TRAVEL LIMITER SPACER
KCKG0019 CARTRIDGE TUBE
KCMU0021 O-RING - FORK - BASE VALVE
ZCKGB017 O-RING - FORK BOTTOM PLUG
KCC60069 FORK BOTTOM PLUG – ADJUSTABLE
KCC60048 ADJUSTMENT SCREW – FORK BOTTOM PLUG
ZCMUOR03 O-RING – ADJUSTMENT SCREW
KCCS0031 RING CLIP – FORK ADJUSTMENT SCREW
36
KCCS0007 FORK GLIDE RING
KAMU0001 FORK LOWER – COMPLETE – BRAKE SIDE
1 TCHA0107FLL FRONT FENDER - FLO YELLOW
1 TCHA0107x FRONT FENDER x – DENOTES COLOR BLK, WHT, YEL, FLO
1A HCBF0616 FENDER BOLT, M6X16mm FLANGE HEAD (4 REQ’D)
2 TCC60002W NUMBER PLATE – FRONT
2 TCC60002x FRONT PLATE x – DENOTES COLOR BLK, WHT, YEL
2A HCBF0616 M6X16mm FLANGE HEAD BOLT – FRONT NUMBER PLATE MOUNT
3 & 4 TCCJ0005FLL RADIATOR SHROUD SET (LEFT & RIGHT) – FLO YELLOW
3 & 4 TCCJ0005x RADIATOR SHROUD SET x - COLOR BLK, WHT, YEL, FLO
5 TCHA0001 FUEL TANK – NO CAP OR PETCOCK
5A HCFH0620 M6X20mm PHILIPS HEAD SCREW – SEAT & SHROUD HOLD
5B TCHA0005 SPACER – SEAT & SHROUD HOLD
5C TCHA0006 SPACER – FRONT TANK MOUNT (2 REQ’D)
5D HCBC0685 M6X85mm SHCS – FRONT TANK MOUNT
5E HCNL0601 M6 LOCK NUT – FRONT TANK MOUNT BOLT
5F HCBC0645 M6X45mm SOCKET HEAD CAP SCREW
9C MCMU0013 STRAP HANDLE
10 & 11 TCCJ0003W NUMBER PLATE SET (LEFT AND RIGHT) - WHITE
10 & 11 TCCJ0003x NUMBER PLATE SET x – DENOTES COLOR BLK, WHT, YEL
10A HCBF0616 M6X16mm FLANGE HEAD BOLT – FRONT SECURE
10B HCBF0620 M6X20mm FLANGE HEAD BOLT – FENDER & REAR SECURE
10C HCNF0602 M6 NYLOC FLANGE NUT
10D HCBF0616 M6X16mm FLANGE HEAD BOLT – FRONT SECURE
10E HCBF0620 M6X20mm FLANGE HEAD BOLT – FENDER & REAR SECURE
3 BCMU0501 SEAL – BRAKE PEDAL (2 REQ’D)
4A BCMU0029 BRAKE PEDAL – ASSEMBLY 50cc – WITH TOE PIECE
4B BCMU0023T TOE PIECE
4C HCBC0501 M5X 12mm SOCKET HEAD CAP SCREW
5 BCMUSP02 BRAKE RETURN SPRING
6 HCBC0601 M6X16mm SOCKET HEAD CAP SCREWS
7 FCEX0018 BRAKE ADJUST ECCENTRIC
8 BACJ0003 PUSH ROD, REAR BRAKE
9 BCKG0006 WHEEL SPACER - FLOATING CARRIER
10 BCKG0103 BRAKE CARRIER WITH PAD
11 HCBF0635 M6X35mm FLANGE HEAD BOLT
12 HCBF0620 M6X20mm FLANGE HEAD BOLT
13A HCCC0000 BRAKE HOSE CLAMP (2 REQ’D) for hose with clear cover
13B HCCC0006 BRAKE HOSE CLAMP (2 REQ’D) for hose with black cover
14 HCPP0832 BRAKE HOSE CLAMP FASTENER (2 REQ’D)
15 BCMU0502 BRAKE ROTOR
16 HCBC0601 M6X16mm SOCKET HEAD CAP SCREWS (5 REQ’D)
17 HCBF0620 M6X20mm FLANGE HEAD BOLT (2 REQ’D)
18 BCKG0012 BRAKE – MASTER CYLINDER - REAR
19 BCKG0010 REPLACEMENT BRAKE HOSE
20 BCKG0013 CALIPER – REAR BRAKE
21 BCMU0022 BRAKE – RUBBER CAP
ACCESSORY
ACCESSORY
ACCESSORY
ACCESSORY
ACCESSORY
ACCESSORY
ACCESSORY
ACCESSORY
ACCESSORY
BKKG0001 BRAKE PADS WITH “E” CLIP
BCKG0031 BLEED KIT (MULTIPLE SYRINGES, FITTINGS & HOSE)
BCKG0014 FITTING KIT
BCKG0015 MASTER CYLINDER PISTON / SEAL KIT
BCKG0016 RESERVOIR SEAL KIT
BCKG0017 CALIPER BOLT / O-RING KIT
BCKG0018 CALIPER PISTON / SEAL KIT
BCKG0019 PAD RETURN SPRING (4 LEG SPRING)
1 SACJ2012 SHOCK ABSORBER
2 SCMU0043 SHOCK – BEARING SPERICAL SHOCK MOUNT – (2REQ’D)
3 SCMU0039 O-RING – SHOCK – BUSHING (4 REQ’D)
4 SCMU0042 SHOCK – MOUNT BUSHING (4 REQ’D)
5 SCMU0058 SHOCK – WHITE NYLON TIP SET SCREW M6-1.0
6 SCMU0056 SHOCK – SLEEVE BLACK
7 SCMU0100 BUMPER – TAPPERED - SHOCK
8 SCMU0040 SHOCK – SPRING PAD
9 SCMU0054 SHOCK SPRING PERCH
10 SCMUOH05 SPRING – STANDARD (285 lb/in)
10 SCMUOH04 SPRING – LIGHT (275 lb/in)
10 SCMUOH06 SPRING – HEAVY (295 lb/in)
11 HCBF1040 M10X40 FLANGE HEAD BOLT
ACCESSORY
SKC60002 REBUILD KIT – CARD SHOCK
41
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Parts – Shock - Inside
REF#
PART #
DESCRIPTION
Rear Shock
1 SCMU0037 O-RING LOW SPEED COMP ADJUSTER
2 SCMU0038 O-RING HIGH SPEED COMP ADJUSTER
3 SCMU0036 O-RING COMP ADJUSTER CAP
4 SCC60007 O-RING COMPRESSION ADJUSTER
5 SCMU0051 O-RING - IFP
6 SCMU0052 IFP SEAL BAND
7 SCMU0033 O-RING SHOCK BASE
8 SCMU0050 RESERVOIR CAP RETAINER RING
9 SCMU0035 O-RING CHARGE CAP
10 HCBB0506 M5 X 6mm LONG BUTTON HEAD STAINLESS STEEL
11 SCMU0044 SEAL HEAD BUMPER
12 SCMU0048 SHAFT BUSHING
13 SCMU0046 X-RING SEAL
14 SCMU0034 O-RING SEAL HEAD
15 SCMU0047 SPACER - X-RING
16 SCMU0045 DUST SEAL
17 SCC60014 PISTON BAND
25A HCCC0000 BRAKE HOSE CLAMP (2 REQ’D) for hose with clear cover
25B HCCC0006 BRAKE HOSE CLAMP (2 REQ’D) for hose with black cover
26 HCPP0832 BRAKE HOSE CLAMP FASTENER (2 REQ’D)
43
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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 do not feel comfortable with the service work log on to:
www.cobramotorcycle.com to find a cobra dealer or call 517-437-9100.
Engine Service
One method for determining whether the top end of your engine needs rebuilt is
to perform a wide open throttle kicking compression test. Before performing the
procedure please read the caution notes below.
CAUTION:
• There is a large wide range of variability in reading compression gauges.
• The head volume of this Cobra Motorcycle is very small and requires 20 kicks
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
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
Your Values
Procedure for Compression Testing
1. Shut off the fuel petcock.
2. Install the compression gauge into the spark plug hole.
always set the squishclearanceofyourenginetofactoryspecifications.
For base gasket replacementusethecode(seefigure31forlocation)alongwith
the table below to reorder thecorrectthicknessgasket.
SuppliedBase
GasketThi
mm
Tolerances will affecttheactualgasketthicknesses.
negativeeffectsof
Tools required
• 17mm wrench
• 1mm flexible
• measurement calipers
you can
Figure 31
NOTE:
Code
#
3 0.3
4 0.4
5 0.5
6 0.6
7 0.7
8 0.8
ckness
inch Part #
0.012 ZCMU0703
0.015 ZCKG0501
0.020 ZCMU0705
0.024 ZCMU0706
0.028 ZCMU0707
0.031 ZCMU0708
Cobra #
45
Page 46
If top end parts are changed during the course of the maintenance, the squish
clearance should be measured, and possibly a different base gasket will be
required.
The easiest way to measure squish clearance is with 1mm to 1.5mm thick
flexible solder wire (available through most popular electronic stores). The
process is as follows:
• Assemble the top end of the engine with either; 1) the crankcase stamp
recommended base gasket or, 2) if assembling with a new set of cases
assemble with a 0.4mm (0.015”) base gasket, and torque the head nuts to
the proper torque specifications leaving off the spark plug and ignition cover
(piston rings can be left off to ease of assembly).
• Carefully insert the solder wire though the spark plug hole, into the cylinder
far enough such that the tip of the wire touches the left or right side cylinder
wall (not the front or back as the piston will rock more and give incorrect
measurement).
• Hold the wire at this position and rotate the crankshaft, by the flywheel nut (or
kick lever) three revolutions to crush the solder wire to be measured.
CAUTION:
If you rotate the flywheel nut in a counterclockwise direction there is a risk of
loosening the nut.
• Pull out the wire and measure the solder thickness at the thinnest location
near its tip accurately with the thin tips of calipers.
• Adjust base gasket thickness as necessary to get the desired value.
Upon completion, your final assembly squish clearance should agree with the
chart below
46
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Engine Removal
To service the bottom end/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 Allen wrench
• 7 mm nut driver, flat or Phillip, screwdriver for hose clamps
• Spring remover
• Flywheel / clutch puller (#MCMUTL70)
• Clutch nut removal tool (#ECMU0078)
• CFD gear stop (#EAMU0004)
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 (19mm socket).
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.
Complete Engine Disassembly Procedure
1. Remove the ignition cover (4mm Allen)
2. Remove the bolt from the water pump shaft (4mm Allen) and slide off the
belt cover and the water pump belt
3. Using a flywheel holding tool and 14mm socket remove the nut that
secures the flywheel.
4. Using the Cobra flywheel / clutch puller (#MCMUTL70), remove the
flywheel from the crankshaft.
5. Remove the stator (4mm Allen).
Page 48
6. Remove the left hand thread nut holding the CFD to the transmission input
INSPECTION NOTE:
INSPECTION NOTE:
shaft using the CFD gear stop (#EAMU0004) and a 19mm socket.
7. Remove the clutch nut / starter gear that holds on the clutch using the
clutch nut removal tool (#ECMU0078).
8. With the Cobra flywheel / clutch puller (#MCMUTL70), remove the clutch
from the crankshaft (details in Clutch Service portion of this manual).
Top End Disassembly Procedure
1. Remove the cylinder head nuts (10mm).
2. Remove the cylinder head outer.
3. Remove the cylinder head insert.
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 muriatic 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.
Muriatic acid can be dangerous. Follow the manufacturer’s instructions closely.
5. Remove the piston clip with a scribe.
6. Remove the piston pin with a piston pin remover
48
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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 0.006” (0.16 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.
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 2 months.
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. Press in the water pump assembly
5. Tap both ways axially then verify easy rotation.
6. Inspect the crankshaft for proper true geometry
(no more than 0.002 “, 0.05mm, measured at
bearing journal area while supported from the
ends).
7. Insert case bolts with the proper lengths at the
locations shown.
8. Torque to 12Nm (105in-lb) in the pattern shown
here.
Page 50
9. Trim away any excess gasket material
if necessary.
NOTE: Check engine mount holes for excess material that may cause problems
in engine installation.
10. Install the piston with new wrist pin bearing and, pin and clips.
CAUTION:
Be sure to install 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.
11. Install the piston rings.
CAUTION:
Ring end gap should be no less than 0.006” (0.016mm) and no more than 0.020”
(0.5mm)
12. Install the base gasket.
CAUTION:
See base gasket selection at the beginning of service section.
13. 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.
14. Install cylinder head insert.
NOTE: A light application of silicone grease can help hold the
O-rings into position during assembly.
15. Install O-RINGs as shown in figure 33.
16. Install the cylinder head.
17. Install the washers (with flat side down) and nuts. Torque to
123 in-lb (14 Nm)
Figure 33
18. Install reed and intake manifold with new gasket. Torque to 55 in-lb. (6.2Nm).
CAUTION:
The intake manifold bolts will require being checked and torque values reset after
a few heat cycles.
19. Leak check the engine at 20 psi to ensure proper seal.
20. Install stator reinstalling the grommet and wires.
21. Install the rotor per Rotor Installation section, under the S3:
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Ignition portion of this manual.
22. Install the water pump outlet pipe (apply 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 bench
23. Install the CFD.
24. Install the clutch per Clutch Installation section in this manual.
25. Install the coolant drain plug with copper washer (11 ft-lb, 15 Nm).
26. Make sure that the exhaust spacer is on the cylinder (53 in-lb, 6 Nm).
27. 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
New for 2014, Cobra has again improved the clutch design. The new washer
stacks are similar but of a different more heat resistant material, the shoulder
bolts have been replaced with a patent pending sleeve bolt assembly, and the
shoes and basket have been modified to improve the oil flow though.
The sleeve bolts of the 5GX provide a low uniform stress, minimal heat transfer,
and allow channels for flushing the clutch fibers out of the washer stacks allowing
a long time between part replacement provided you operate with 10 oz of clean
Clutch Milk.
As before, the new washer stacks are being double sorted at the factory. They
are first sorted by measured height. Secondly, each stack with bolt is sorted by
measured engagement force. The stacks in each set of three will measure within
0.05mm (0.002”).
There are many variables in an automatic centrifugal clutch. These variables are
set to world class standards from the factory but will change over time as the
components wear, relax, and just plain get used.
Please see the Tuning Clutch portion of this manual for more helpful info.
Tools recommended for clutch service:
• Universal clutch puller- a universal puller that pulls the clutch, main drive gear
and rotor. (Part # MCMUTL70).
• 5mm T-handle
• T25 Torx
• Accurate torque wrench in the range of 16 Nm (12 ft-lb, 144 in-lb).
1. Drain the engine transmission oil and remove the clutch cover.
51
Page 52
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)
4. Install each of the 3 6mm socket head cap
screws (clutch cover bolts can be used)
until each is similarly snug and the puller
looks square to the end of the crank
5. One at a time, tighten each of the 1/4 turn
until the clutch 'pops' off
Figure 30 Figure 31 Clutch puller installation
CAUTION:
Do not use a jaw type puller.
CAUTION:
It is possible to cause damage to the piston when using the piston stop. Care
must be used when removing and installing the clutch arbor and using the piston
stop.
6. If necessary apply heat to the center clutch hub.
CAUTION:
Do not heat the crankshaft threads or the aluminum shoes.
7. 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.
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CLUTCH WASHER STACKUPS:
Stack
Total
Flying Saucers
Turned Away
Std. Flat
HIT
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 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.
CAUTION:
If you do not apply heat to the arbor near the clutch bolt threads you will very
likely break the Torx bit upon attempted removal.
The spring stacks in your Cobra clutch will contain 11 individual springs and flat
washer(s) 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. If you are unsure call the Cobra Technical
Support Group 517 437 9100 and consult the experts.
5GX CLUTCH ASSEMBLY REFERENCE DRAWING
REF # PART # DESCRIPTION
1 CAMU0009 Set of three shoes, springs, bolts, flat washers & nuts
2 CAMU0014 Set Of three springs, washers, bolts & nuts
Not Shown
Figure 32 Some configuration of clutch spring stack. Each ‘spring’ stack contains multiple
springs (Belleville washers) - arranged into three, four, or five ‘flying saucers’, or turned away
against the flat washer(s). Shown is the 5 ½ stack..
CAMU0002 Complete assembled clutch
(Arbor, shoes and washer stacks)
Springs
5 ½ 11 5 1 VARIED HARD
4 11 4 3 VARIED SOFTER
53
or Cymbal
Pairs
or Dish
Stacked
Washer(s)
Page 54
Clutch adjustment washers
Your Cobra comes stock with flat washer(s) at the bottom of the spring washer
stack. 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).
NOTE: HKAM022 Clutch shim kit includes - 3 each .005”, .010”, .015” and .020”
shims along with 2 clutch to hub spacers and 2 thin clutch to hub spacers.
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.
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, contact
the Cobra Technical Support Group before making adjustments.
Clutch shoe wear:
• This can be measured by the overall diameter of the shoes installed on the
arbor. This measurement should be greater than 80.5mm
• 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.
• 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.
Clutch basket wear:
• The internal diameter of a new clutch basket should measure ˜84.10mm.
Over time the clutch shoes will wear the internal surface down creating a
bigger ID and causing a later engagement. The maximum ID we recommend
to allow is 84.25mm.
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INSPECTION NOTE:
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. It is
important to train your rider NOT to be a throttle 'blipper'.
CLUTCH ASSEMBLY:
1. Start with a new set of pre- assembled washer stacks or a cleaned,
reassembled set of washer stacks and bolts.
CAUTION:
It is also important that all three shoes are stacked the same. (See figure 32)
2. Clean the threads of the stack bolt and the clutch with brake cleaner
removing all old thread locking material.
3. Assemble the stacks and shoes on the arbor using high strength thread lock
material to the stack bolt and tighten to 16 Nm (12 ft-lb, 144 in-lb).
CAUTION:
Avoid allowing excess thread lock material to contact the spring washers and the
clutch or the clutch is likely to malfunction.
4. Clean the threads of the crank shaft and the clutch nut.
5. Install the clutch arbor on the crank. Making sure that the backing spacer in
place on the crank.
6. Apply high strength thread locking agent to the threads and install the clutch
nut and torque to 40 ft-lb (54Nm).
• There must be in / out play in installed clutch, 0.3mm to 1.0 mm
(0.012” to 0.040”).
• This should be adjusted with the ECMU0040T and ECMU0040
shims
• A blue clutch drum is worn out from excessive slippage or improper
lubrication.
7. Install the clutch cover tightening the bolts from inside out. (8 or 10 mm
socket, 5.8 ft-lb, 7.8 Nm).
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 (295 ml (10.0 oz) Cobra 3 Shoe Clutch Milk (Part #
MCMUGF32).
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Ignition
Stator care
Stator failure could 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 connections are free of dirt.
The proper ignition timing for this model of is at 0.040” before Top Dead Center
(that means 0.040” before the piston reaches the highest point of it’s travel in the
cylinder).
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 (ECMU0079)
• Universal clutch puller- a universal puller that pulls the clutch, main drive gear
and rotor. (Part # MCMUTL70).
TIMING YOUR IGNITION:
1. Remove the spark plug.
2. Insert the dial indicator into the spark plug hole.
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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 0.040” (1.0mm)
from top dead center.
8. At this position the line on the rotor should align with the center of the stator
coil at 5 o’clock position on stator frame. If not loosen the three 5mm bolts to
adjust the stator.
0.040”
before
TDC
Figure 39, Lining up the line on the rotor
with the line on the stator.
Figure 40, Using a dial indicator to measure
piston height for setting ignition timing.
ROTOR INSTALLATION:
1. Torque the nut on the rotor to 30 ft-lb (45 Nm) with medium strength (blue)
thread locking agent.
2. Recheck the timing following the procedure of timing your ignition.
3. Install the water pump belt back on.
4. Bolt the ignition cover back on.
5. Put the spark plug back in, and firmly stick the spark plug cap onto the spark
plug.
Cooling System
Radiator fluid removal:
Remove the coolant drain plug (13mm bolt) on the front of the engine cases.
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NOTE: Inspect the old coolant for evidence of oil, combustion byproducts (black
‘oil slick’ stuff) or other things that may indicate a problem.
Tools recommended for impeller service:
• Flat head screwdriver
• 13mm- hex wrench
• 3mm hex key
• 4mm hex key
• 5mm hex key
• 8mm hex key
• Water Pump Installation tool
MCMUTL09, 2010 and newer JR & King
MCMUTL08, 2009 and older JR models
• Slide hammer with
• fitting to thread into threads on end of shaft (M5x1.0)
• single and double hook ends for removing plastic impeller
•
Dead blow hammer
COBRA IMPELLER SERVICE INSTRUCTIONS
1. Remove radiator cap and drain engine coolant as described above.
NOTE: If the impeller is damaged or broken completely back flush the coolant
system to ensure no solid pieces are in the system.
2. Remove ignition cover using a 4mm hex key (four places)
3. Stick a 3mm hex key in the water pump shaft cross hole, and remove belt
retainer screw using a 4mm hex key. (Figure 42 - item 1)
4. Remove belt retainer, water pump belt and water pump fan pulley.
5. Remove bearing retainer screw using a 3mm hex key.
6. Thread a slide hammer onto the end of the water pump shaft and remove the
assembly.
NOTE: It is quite common for the older plastic impellers to fall off the end of the
shaft during this step of the process if that is the case, then follow the steps at
the end of this section to remove the seal and impeller.
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7. Clean any debris or particles from the bore and use some light emery cloth to
remove any scratches in the surface that the removal process may have
created.
8. Lubricate the bore with grease.
9. Prepare for assembly by installing the water pump assembly into the
assembly tool and align the tool with engine case making sure alignment pin
is in proper hole.
CAUTION:
Damage may occur if one attempts to install the water pump and the device is
not orientated correctly. If the tool does not sit flat against the cases, the
orientation of the tool to the engine is not correct. Make sure that the top
alignment pin is in the 2
nd
the 2
unthreaded hole, and that the relief for the stator bolt head is oriented
nd
unthreaded hole, the bottom alignment pin is also in
toward the stator.
10. Hold the installation tool firmly against the engine case and tap on the end of
the water pump shaft with a dead blow hammer until the insertion punch is
needed
11. Continue driving the assembly with the punch until the head is flush.
NOTE: The insertion punch is 0.010” (0.25mm) longer than the housing so as to
seat the water pump assembly just in from the case surface.
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12. The assembly is installed properly when the retaining screw can be tightened
and it does not cause a bind on the spinning shaft (use medium strength
thread lock on the retainer screw).
NOTE: It may be necessary to tap the water pump shaft in (hammer) and out
(with slide hammer) to insure proper free operation of the shaft.
13. Reinstall the pulley, belt and fan cover using a 3mm hex key to stop the
rotation of the water pump assembly while tightening with medium strength
thread lock to 10 ft-lb (14Nm).
14. Reinstall the cover
NOTE: Refill the coolant system with 50/50 antifreeze-coolant / distilled water.
CAUTION:
Do not mix Propylene Glycol based coolant / antifreeze solutions with Ethylene
Glycol based coolant / antifreeze solutions.
Fuel & Air System
Carburetor
Tools recommended for carburetor service:
• Small flat head screwdriver
• WD-40
• 8mm socket
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.
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If the engine is running rich on the top end it should be leaned out. Leaning it out
Figure 45
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
have water or dirt in the carburetor bowl. Use automotive carburetor cleaner or
WD-40 to clean the carburetor inside and out.
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 and remove
the carburetor
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
61
Proper carburetor top
installation And location of rectangular
slide indexing pin and vent elbows.
Page 62
compressed air.
7. Blow out the fuel passages with compressed air.
8. Assemble the carburetor
9. Install the carburetor onto the motorcycle.
CAUTION:
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 45.
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.
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.
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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Rear wheel pullers
Disassembly:
1. Remove axle, and
back wheel
assembly.
2. Pull the rear wheel
pullers out of the
back of the swing
arm.
Figure 47
Rear wheel alignment:
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).
Brakes
Check before each ride:
• Make sure the brake does not have any leaks by holding the lever in while
checking hose connections.
• Make sure the brake lever pressure is OK by pulling in on the lever and
ensuring full braking performance is achieved before the lever touches the
handlebar. If this is not the case, pump the lever several times until the lever
feels firm.
• Always make sure the rotor and brake pads are free from oil and grease.
Clean the rotor with mild dish soap or alcohol. Contaminated pads must be
replaced.
• Ensure that the brake caliper is centered over the brake rotor. It a correction
is needed, Cobra has thin brake shims to help make minor adjustments in
alignment.
• Always leave adequate free-play in the lever or pedal.
CAUTION:
This brake system uses only DOT 4 or 5.1 brake fluid!
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Front Forks
Tools recommended for front fork service:
• Flat head screwdriver
•
Hammer
• Pick
•
Seal driver MCMUTL02
•
9/16” (loose 14 mm) wrench
25mm wrench or socket
•
•
2.5 wt fork oil
FORK DISASSEMBLY PROCEDURES:
o Using the 25mm wrench, remove the fork cap.
o Drain the fork oil into a suitable container.
o Disconnect the fork cap from the damper rod (9/16” wrench & 25mm wrench).
o Disconnect the damper assembly from the fork leg by removing the large
aluminum bolt from the bottom of the fork leg (22mm wrench).
o Pry the dust seal (swiper) from its position with a small screw driver.
o Using a pick, remove the wire retaining ring holding the fork seals into place.
o ‘Pop’ the fork seal out by forcibly pulling on both ends of the fork tube
assembly, thus separating the inner from the outer tube.
o Remove the bushings
o Clean all components to be reused.
FORK ASSEMBLY PROCEDURES:
CAUTION:
Make sure all components are clean before assembly.
CAUTION:
Be sure to apply oil to the new fork seal and other components before installing.
1. Slide dust seal (swiper) (#6) onto lower fork leg.
2. Slide retaining ring (#5) onto lower fork leg.
3. CAREFULLY slide seal (#4) onto lower fork leg with spring facing away from
snap ring.
Figure 46
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CAUTION:
It is helpful to cover the sharp corners of the fork leg with tape or thin plastic
before sliding on the new seal. Also take care that the inner lip is not folded over
when installing.
4. Slide bushing (#3) onto lower fork leg.
5. Install the glide ring into groove on lower fork leg.
6. Slide the bushing over the glide ring about 1/4" to hold the glide ring in the
groove.
7. Insert the lower leg assembly into the upper fork tube about 5-6".
8. Use a seal driver to drive the seal into the upper tube.
9. Install the retaining ring. Make sure it is properly seated in the groove.
10. Snap the dust seal (swiper) into the groove in the upper tube.
11. Reinstall the damper cartridge assembly to the fork leg. Secure the large bolt
with 22 mm wrench to 35 ft-lb with green thread locking agent.
12. Fill with 3.6 oz (107 ml) 2.5 wt fork oil should measure 6 mm (0.25”) above
the damper cartridge tube with spring removed. (This oil volume works out to
leave an oil height of 120mm from top of outer tube with forks collapsed,
damper rod down, and spring removed).
13. Install the fork spring
14. Connect the cartridge rod to the cap and tighten to 12 ft-lb (16 Nm).
CAUTION:
The damper rod is hollow and will break if the nut is over tightened (proper torque
is 12 ft-lb, 16 Nm).
Because of different rider weights, sizes and riding styles, we offer various
suspension options:
See Optional Components section of this manual for details on these and other
optional components for your Cobra Motorcycle.
Rear Shock
The rear shock is fully serviceable but it is recommended that only trained
professionals should service your shock. Contact Cobra for questions and
service of your CX50 SR shock.
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Tuning
Clutch
There are performance characteristics to observe and things to measure.
1) Performance characteristics to observe
a) Clutch coming in too late
i) Engine rev’s to a high RPM before moving the motorcycle
ii) Clutch never fully engages on a reasonable straight stretch
iii) Basket turns blue in short amount of time
b) Clutch coming in too early
i) Motorcycle moves too soon when accelerating off idle
ii) Motorcycle moves but not with much power
iii) Clutch fully engages before the ‘power band’ kicks in
2) Things to measure that can have an effect
a) Spring washer configuration
b) Spring stack without flat washer
c) Thickness of flat washer
d) Individual spring washer thickness
e) Individual spring washer height
f) Effective bolt shoulder length
g) Shoe thickness (difficult to measure accurately - can only be approximated
by the size of the step where it sticks out of the basket)
h) Basket has worn and is too large
There is a relationship between observed characteristics and the things
that can be measured
If a clutch comes in too early, it means that clutch spring stack is not providing
enough force to keep the shoes from being thrown out to the clutch basket at
the proper time with the given shoes, basket, arbor, and bolt. This can be due to:
1. Clutch spring stack is to short
• Wrong configuration
• Sacked out (over stressed) washers
• Too thin a flat shim in the stack
2. Spring rate too low (wrong configuration with proper stack height)
3. Clutch arbor shoulder bolt is too long
If a clutch comes in too late, it means that clutch spring stack is providingtoo much force to keep the shoes from being thrown out to the clutch basket at the
proper time with the given shoes, basket, arbor, and bolt. This can be due to:
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1. Clutch spring stack to tall
• Wrong configuration
• Too thick a flat shim in the stack
2. Spring rate too high (wrong configuration with proper stack height)
3. Clutch arbor shoulder bolt is too short
4. Clutch shoe material has worn too thin
5. Clutch basket has worn too much and is too large of a diameter
With the exceptions of component failures, generally two things will occur:
1) The clutch shoes will wear causing the clutch to engage later, and
2) The springs will sack causing the clutch to engage earlier.
Typically the springs will sack at a quicker rate than the shoes will wear, meaning
that an un-tampered clutch that worked fine will ultimately hit too early at some
time. When this occurs it is easily remedied with a new spring stack or a thicker
flat shim. Because the shoes have worn, a thinner flat washer may be needed
with the fresh new springs to allow proper clutch engagement.
One thing to remember:
If your clutch is hitting fine, don’t mess with it!
Some things to remember to aid clutch life
Change oil each ride
•
•
Gear to the low side
• Avoid mud if possible
• (Cut mud practice to 1 lap or none)
•
Stay on the gas (no throttle blipping)
Run more air pressure to allow wheels to spin (helps throttle steer)
•
Make sure wheels spin freely (no bent rotors, dragging brakes, chain too
•
tight, etc
Make sure the engines pulls cleanly and strong by having properly
•
)
maintained engine with correct ignition timing and carburetion.
With the exceptions of component failures, generally two things will occur:
• The clutch shoes will wear causing the clutch to engage later, and
• The springs will sack causing the clutch to engage earlier.
Typically the springs will sack at a quicker rate than the shoes will wear, meaning
that an un-tampered clutch that worked fine will ultimately hit too early at some
time. When this occurs it is easily remedied with a new spring stack or a thicker
flat shim. Because the shoes have worn, a thinner flat washer may be needed
with the fresh new springs to allow proper clutch engagement.
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Effective length of the shoulderontheclutcharborbolt(seeFigureC1).Nominal
is 16.00mm (0.630
”). As thisdecreases,thespringstackneedstodecrease
equally. This can change duetotheshoulderbolt‘setting’intothearbor(seeC2)
If your effective shoulder lengthisoff,oryourshoesareworn,adjusttheheight
of your overall combined springstackaccordingly(i.e.ifyoureffectiveshoulder
of the16.00measurement,decreasetheoverallcombined
spring stack height by 0.5mm,orifyourshoesarewornby0.5mm,increasethe
overall combined spring stackheightby0.5mm).
Frequently asked questions
Q: When should the springsbereplaced?
When the clutch ‘hit’occurstooearlyortoolate.
Q: Should the clutch springsbereplacediftheshoeswiggleonthearbor?
A: Not if the clutch is‘hitting’correctly.Don’tmesswithit
Q: What is the acceptable toleranceonanyofthemeasurements
A: For the most partthatdoesnotmatter.Sufficeittosaythatanyefforts
to make the three shoesbehaveidenticallywillmakethebestperforming
1.1.2.2. Smaller quantity / lower level – less bottoming resistance,
1.2. Fork 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.
1.3. Gas pressure – always bleed off any pressure.
1.4. Fork height
1.4.1. Rise in clamps for quicker turning.
1.4.2. Lower in clamps for improved straight line stability.
1.5. Compression damping
1.5.1. Harder (more damping, slower) – adds resistance to the
suspension motion when the suspension is compressing.
1.5.2. Softer (less damping, quicker) – reduces resistance to the
suspension motion when the suspension is compressing
1.6. Rebound damping
1.6.1. Harder (more damping, slower) – adds resistance to the
suspension motion when the suspension is returning to full length.
1.6.2. Softer (less damping, quicker) - reduces resistance to the
suspension motion when the suspension is returning to full length
2. Rear shock
2.1. Preload adjustment
2.1.1. More preload (greater distance) – less race sag.
2.1.2. Less preload (smaller distance) – more race sag.
2.2. Shock spring
2.2.1. Stiffer spring – stiffer throughout the travel.
2.2.2. Less stiff spring – less stiff throughout the travel.
2.3. Compression damping
2.3.1. Harder (more damping, slower) – adds resistance to the
suspension motion when the suspension is compressing.
2.3.2. Softer (less damping, quicker) – reduces resistance to the
suspension motion when the suspension is compressing.
2.4. Rebound damping
2.4.1. Harder (more damping, slower) – adds resistance to the
suspension motion when the suspension is returning to full length.
2.4.2. Softer (less damping, quicker) - reduces resistance to the
suspension motion when the suspension is returning to full length
resistance, stiffer near the end of the travel.
less stiff near the end of the travel.
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Front Fork Operation
The front suspension on the CX50SR works under the principals of hydraulic damping,
and it features full adjustability to help tune the fork to meet each rider’s needs. The
CARD fork contains MXT ‘Smart Leg’ technology that provides very progressive
operation; allowing a small bike to perform well on track surfaces ripped up by larger
machines.
The key to Smart Leg technology is to understand that each leg has a different
role. The brake side leg features a conventional open cartridge. This cartridge
handles both standard compression and rebound damping duties. Rebound
damping is adjustable on the fork cap, and compression damping is adjusted at
the bottom of the fork. The other leg (the Smart Leg) has no rebound damping,
and it contains both a speed sensitive compression damping mechanism as well
as a position sensitive one. This design allows for a firm low speed response,
controlling rapid chassis pitch, which promotes stability and control. The fork
produces significantly less mid and high-speed compression until it travels into
the progressive / speed sensitive portion of the smart leg. The speed sensitive
compression component is adjustable at the top of the fork.
The combination of the Smart Leg and the conventional leg allows the fork to be
very supple throughout all low amplitude operation and yet take punishing hits;
producing a progressively increasing damping rate that slows the forks
movement as it approaches full bottom. Therefore, the Smart Leg also acts as a
hydraulic bottoming control device. Finally, the large degree of adjustability in
both legs allows the fork to be tuned to meet each rider’s size, ability, and type of
riding they do (motocross, off-road, flat track, etc).
Fork Damping Adjustments
Tools required
• Small flat blade screwdriver
The speed at which the fork rebounds can be adjusted
at the top of the conventional leg. Turning the
adjustment screw clockwise slows the rate at which
the fork extends after being compressed, and likewise,
turning the screw counterclockwise returns the leg to its
extended position faster. As
shown in the figure, ‘S’ (slower)
and ‘F’ (faster) are etched into
the cap as an adjustment guide.
At the base of the conventional leg is another adjustment
screw that controls the amount of compression damping.
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Turning this screw clockwise increases damping and turning it counter-clockwise
Symptom
Action
will decrease it. This is illustrated by the “HARD” and “SOFT” in the figure at the
right.
The Smart Leg cap is labeled “Speed Sensitive
Bottoming Control”, and this adjuster provides a range
of control over how progressive the fork feels. Turning
the screw clockwise increases the fork’s resistance to
bottoming, while turning the screw counter-clockwise
decreases it. On the track, this effect will be felt on
sections where the fork is forced to move very quickly
such as on harsh landings or when traversing sharp
edged bumps.
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
Rear Shock Adjustments
Always start with standard settings and make damping changes in no more than
two click increments and only make one change at a time.
Rear end feels stiff on small bumps Softer Low Speed Compression
Damping
Rear end ‘sways’ on straights Harder Low Speed Compression
Damping
Bike tends to jump ‘rear end high’ Harder High Speed Compression
Bike tends to jump ‘rear end low’ Softer High Speed Compression
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 Low and
High Speed Compression
Rear end feels stiff under acceleration
bumps.
Proactive Suspension Adjustments
Softer Rebound and/or Stiffer Low
Speed Compression Damping
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Situation
Actions
Once you have the suspension adjusted for decent overall feel, you can make
proactive adjustments when faced with different racing conditions.
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.
Shock preload
Loosen the set screw and turn the spring perch in
full turn increments to get the desired sag settings.
NOTE:
Always leave the spring perch rotated in such
position so that the set screw is easily accessible.
Shock Damping
11. Adjustment of rebound damping 12. Adjustment of compression damping
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.
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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
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)
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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.
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.
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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
ii) Has large dent in it
e) Compression is low
i) Piston
ii) Rings
f) Reeds are damaged
g) Ignition timing is incorrect
3) Engine is excessively loud
a) Silencer needs to be repacked
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
ii) Is sour or bad
b) Carburetor is dirty
c) Ignition
i) Spark plug fouled
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ii) Wrong spark plug installed (8339 Champion to be used on ’04 or later & no
mods)
iii) Spark plug cap off
iv) Engine Shut-off ‘kill’ switch is shorted
v) Bad electrical ground
vi) Stator winding damaged
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 high gearing
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
b) Air leak
c)
Carburetor jets are dirty
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Index
Air Filter Maintenance ................... 14
Airbox
Parts .......................................... 18