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 ECX50 IS A COMPETITION MODEL ONLY AND IS NOT
MANUFACTURED FOR, NOR SHOULD IT BE USED ON PUBLIC ST REETS, ROADS
OR HIGHWAYS.
THE USE OF THIS ATV 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 PRODUCT OR AS
THE PARENT, OR LEGAL GUARDIAN OF THE OPERATOR, TO KEEP THIS COBRA
PRODUCT IN PROPER OPERATING CONDITION.
THIS ATV WAS DESIGNED FOR RIDERS THAT WEIGH LESS THAN 110 LBS WITH
FULL RIDING GEAR AND SHOULD NOT BE OPERATED BY RIDERS THAT WEIGH
MORE THAT.
BE SURE THAT THE RIDER ALWAYS WEARS ADEQUATE SAFETY GEAR
EVERYTIME HE OR SHE RIDES THEIR COBRA ATV.
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.
MCE52009 1
Page 4
Table Of Contents
General Information..............................................................................................5
Type 2-stroke, single cylinder, reed valve
Cooling system Liquid-cooled
Coolant 50/50 antifreeze-coolant / distilled water
Displacement 49.8 cc
Bore and stroke 39 mm x 41.7 mm, “V” head
Ignition system Electronic, analog advance
Spark plug Champion 8339-1, 8332-1 hotter, 8904-1 colder
Gap0.023” – 0.025” (0.58 – 0.64 mm)
Ignition timing 0.040” (1.02 mm) BTDC
Fuel type High octane pump gasoline
Oil type
Fuel / oil mix ratios Between 32:1 and 40:1 (after engine Break-In)
RACE FUELS ARE NOT RECOMMENDED
Cobra Venom2-cycle Race Oil
Carburetion 21 mm Dell’Orto PHBG,
Jet Main / Slow (Pilot)98 / 55
Slide / Needle#30 / W-4
Float Height16mm + 0.5mm (0.63” + 0.020”)
Transmission
Speed / ratio Single / 14/38 T
Chain 104 links 420
Transmission / clutch oil type
ft-lb in-lb Nm
Cylinder head nuts 8.8 105 12 M6 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
Clutch nut 40 480 54 M10 x 1.25*
Clutch bolts 12 144 16 M6 x 1.0
CFD nut 55 664 75 ½” x 20 LHT
Units of mm unless otherwise specified
(G) denotes the use of wicking / bearing retainer (green) thread locking agent to
applied to the mating surfaces of the two components but not the threads.
(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.
Size &
Remarks
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CHASSIS Fastener
Torque Value
ft-lb in-lb Nm
Size &
Remarks
Handle bar mounts 15 177 20 8 x 1.25
Handle bar clamps 15 177 20 8 x 1.25
Front engine mount 22 265 30 8 x 1.25
Rear brake lever pivot 10 120 13.68 x 1.25
Upper shock mount 40 480 54 10 x 1.5
Lower shock mount 40 480 54 10 x 1.5
Swingarm pivot 75 900 102 14 x 2.0
Units of mm unless otherwise specified
(R or G) designates that the application requires the use of high strength (red)
thread locking agent applied to the threads.
(B) designates that the application requires the use of medium strength (blue)
thread locking agent applied to the threads.
Optional Suspension Components
Front shock springs
Weight of Rider (lb) Helper Main
Less than 65
65 to 100
Greater than 100
SCEX1080 (RED,
80 LB/IN)
SCEX1095 (YELLOW,
95 LB/IN)
Rear shock springs
Weight of Rider (lb) Main
Less than 50 SCEX2325 (White, 325 LB/IN)
50 to 75 SCEX2350 (Yellow, 350 LB/IN)
Greater than 75 SCEX2375 (Red, 375 LB/IN)
SCEXA145 (RED, 145 LB/IN)
SCEXA155 (YELLOW, 155
LB/IN)
SCEXA165 (BLACK, 165 LB/IN)
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Helper
Fox 8” long main
Spring Rate
Color Part Number
(lb/in)
65 Silver SCEX0065P
80 Red SCEX1080
95 Yellow SCEX1095
110 White SCEDX1110
125 Gold SCEX1125
150 Green SCEX1150
175 Black SCEX0175P
200 Silver SCEX0200P
250 Red SCEX0250P
300 Yellow SCEX0300P
350 White SCEX0350P
spring (front)
Fox 7” long main
105 Orange SCEX1105
115 Green SCEX1115
125 White SCEX2125
135 Blue SCEX1135
145 Red SCEX1145
155 Yellow SCEX1155
165 Black SCEX1165
spring (rear)
300 Red SCEX1300
315 Yellow SCEX1315
330 White SCEX1330
350 Red SCEX1350
375 White SCEX1375
400 Yellow SCEX1400
425 Blue SCEX0425P
450 Green SCEX0450P
475 Black SCEX0475P
500 Purple SCEX0500P
Fox 10” long main
spring (rear)
325 White SCEX2325
350 Yellow SCEX2350
375 Red SCEX2375
400 Black SCEX2400
Spring rate chart for Cobra Fox quad shocks
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Break-In Procedure
Your Cobra Motorcycle is a close-tolerance high performance machine and
break-in time is very important for maximum life and performance. The ECX50
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
93 octane pump gas, or Sunoco MO2X , with Cobra’s specially formulated Cobra Venom2-cycle Race Oil. (Part # MCMUOL02)
CAUTION:
Failure to use proper fuel or oil 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.
• 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 the engine to cool
• Ride for 15 minutes maximum, avoiding prolonged high RPM operation.
• Cool and inspect bike for loose fasteners.
• Next ½ hour of operation, avoid prolonged operation at Wide Open Throttle.
• After 1 hour of operation
oCheck 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.
o Replace the fuel filter.
•After 8 hours of operation have a Certified Cobra Mechanic change the
shock oils.
•Your bike is now ready for the highest level of competition!
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Starting Procedure
Before starting the machine inspect the following:
• Check for proper tire pressure in both tires.
• Observe the chain tension and adjust if necessary.
• Observe the coolant level and fill if necessary.
Verify that the chain rollers and sliders do not have improper wear.
• Verify that the handlebars are tight.
• Check the throttle for smooth operation and sound closing.
• Check for loose bolts and nuts, and re-torque as necessary.
• Verify that the air filter is clean and properly saturated with oil.
• 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 Venom2-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.
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. Pull up the choke knob and turn it to lock it.
2. Kick start the engine.
3. Rev the engine in short spurts, turning the throttle no more than 1/4 open
until the engine will run without the choke.
4. Verify a functional engine shut-off switch by shutting off the engine.
5. 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. Also, for
best clutch performance, warm up the bike before taking off.
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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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.
Maintenance
It is important that you adhere to this maintenance schedule so as to promote the
longevity of your Cobra Motorcycle.
Tips
1. Cobra lubricants:
a. Cobra Clutch Milk has been specifically formulated to meet the
stringent temperature, frictional, and load requirements unique to
the high engine speeds and centrifugal clutch of the Cobra 50cc
motorcycles.
b. Cobra Two Cycle Oil exceeds the JASO FD & ISO-L-EGD
specifications, which are the worlds most stringent requirements on
lubrication, detergency, and smoke. Use only a 2-cycle oil that
meets these specifications.
2. Filling your transmission with more than 8.0 oz (235 cc) of lubricant may
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. A properly maintained machine is safer, faster, and more fun to ride.
6. New chains will stretch on first use. Never install a new chain prior to a
race. Always ‘break’ them in during practice.
7. 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, Acxxxx7xxx is a 2007 MY quad.
Schedule
• 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).
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oCheck 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.
oCheck the rims for signs of stress, like cracks around the rim, spokes
and hub.
•Every 2 hours of operation
o Replace the transmission oil.
•Every 10 hours of operation
o Replace the fork oil.
o Have 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.
Be sure the fuel tank and carburetor have been removed and safely located
away from the welding process.
3. 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.
4. 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.
5. Inspect CFD slip torque every 10 hours of riding or replace the friction
papers and the load spring (Bellville spring) every 20 hours.
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6. 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 real hard to make a clutch that is low maintenance and so only
take it apart if it NEEDS to be maintained.
Replacing Transmission / Clutch Lubricant
Tools needed:
• Minimum of 235 ml (8 oz) Cobra Venom 3 Shoe Clutch Milk (Part #
MCMUGF01).
NOTE:
Up to 350ml (12 oz) can be applied without hurting performance.
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 bike against something or set on stand with oil drain hole.
3. Remove the oil drain plug located on the right side of the engine, on the
clutch cover, near the brake lever (figure 1).
Figure 1
4. After it has drained, reinstall the plug, being sure that the gasket is in place.
5. Reapply oil from oil fill plug 235 cc (8.0 oz) Cobra Venom 3 Shoe Clutch Milk
thru the oil fill plug.
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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:
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 plug, hand tight, being sure the 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(Part
# MCMUGF01) 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 needed:
• 13 mm wrench or socket
• 5mm pin (Screw driver or hex key will do)
Procedure:
1. Loosen the eccentric housing on the swingarm with two 13mm tools.
2. Stick the 5mm pin through the sprocket into the eccentric hole.
3. Push the quad forward or backward, turning the wheels (i.e. the sprocket) in
the direction shown until the desired chain tension is achieved (see fig. 2).
Figure 1
NOTE:
The location of the pin hole is the ‘fattest’ part of the eccentric. Restated, if the
pin hole is all the way forward, the chain is as tight as possible, and if the pin hole
is all the way back, the chain is as loose as possible.
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CAUTION:
Proper chain tension allows no less than ½” (12mm) free play through out the
range of rear suspension travel.
NOTE:
It may be handy to set backwards on the seat and feel the chain as you weight,
and unweight, seat to feel for chain free play.
4. After achieving the proper adjustment retighten the two eccentric pinch
bolts.
CAUTION:
Be sure to remove the pin from the eccentric before riding.
Air Filter Cleaning
This Cobra Motorcycle comes with a unique air filter / air boot unit designed to
facilitate motorcycle service.
Tools recommended for air filter maintenance:
• Srewdriver
• Foam filter oil
Procedure
1. Removed the filter from the carburetor.
2. Clean the filter with cleaning solvent and then again with hot soapy water.
3. Allow it to dry thoroughly.
4. Saturate with foam filter oil and remove excess.
Do not clean the air filter with gasoline or other highly volatile petroleum product.
Cleaning solvent, diesel fuel, or kerosene would be preferred but caution should
still be taken.
NOTE:
The biodegradable air filter oils, greases, and cleansers work acceptably with this
Cobra Motorcycle.
NOTE:
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.
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NOTE:
Make sure you change or clean your filter after each moto or significant ride. We
recommend carrying three or more filters in your toolbox.
• 1 for practice
• 1 for each moto
CAUTION:
Dusty conditions will require more frequent cleaning.
Frictional Drive (CFD)
The Cobra Frictional Drive (CFD) is essentially a 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’ between a minimum torque value,
and a maximum torque value.
The slip torque of the CFD should be checked every 5 hours of operation.
Slip Torque
Minimum 55 75
Maximum 92 125
To properly measure the torque at which the CFD (Cobra Frictional Drive) slips,
one first access the slip clutch by draining the oil and removing the cover
exposing the CFD. Next, brace the CFD gear from turning with a suitable device
(Cobra tool EAMU0004 or similar).
Ft-lb N-m
Using a beam style torque wrench, turn the torque wrench counter clockwise and
observe the torque measurement when the shaft slips relative to the gear. Using
a preset value torque wrench, adjust the setting 55 ft-lb (75 Nm) and observe
whether the wrench clicks first or the shaft slips. If the shaft slips first, the slip
torque is below 55 ft-lb and the CFD needs servicing. If the wrench clicks first,
the CFD is of acceptable value.
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NOTE
To loosen and tighten the blue CFD nut, use a strong wooden object (large
hammer handle) through the spokes of the rear wheel as a brace against the
swingarm to stop transmission shaft rotation.
CAUTION:
The blue CFD nut has left hand threads which require clock-wise rotation to
loosen.
Front end
Toe in adjustment
Riders and parents have provided feedback that they prefer the toe in adjustment
between ½” (12mm) out to ½” (12mm) in. This is set by adjusting the length of
the tie rod assemblies. See figure 3 for direction of turn.
Adjust both wheels so that they have the same amount of toe in.
Figure 3
Steering
The unique Cobra front end will exhibit some free play from the factory and that
the seals (it that’s what you want to call them) will fall out after the first ride. We
have found that this causes no adverse effects and that the looseness does not
get significantly worse as long as the bearings are sprayed with a spray lubricant
(WD40 or similar) upon each ride.
2 CAMU0013 CLUTCH SHOES (SET OF 3) WITH BOLT & WASHERS
3 CCMU0029 CLUTCH ARBOR
4 CAMU0010 SPRINGS, WASHER & BOLT (SET OF 3)
5 HCBS0004 CLUTCH BOLT (3 REQ’D)
6 ECMU0018 CLUTCH NUT, SPECIAL
7 ECMU00120 CLUTCH BASKET WITH NEEDLE BEARING
8 ECMU0119 CLUTCH BEARING
9 ECMU0040 CLUTCH TO HUB SPACER (0.030”, 0.76MM)
ECMU0040T CLUTCH TO HUB SPACER (THIN – 0.015”, 0.38MM)
10 ECMU0132 COOLANT FITTING
11 EAMU0008 CFD HUB / PRESSURE PLATE
12 ECMU0162 PRESSURE PLATE WITH FRICTION MATL, ’08 STYLE
13 ECMU0138 FRICTION PAPER, CFD
14 ECMU0161 GEAR, CFD ’08 STYLE
15 ECMU0159 SPRING WASHER, CFD, 60MM OD
16 ECMU0160 CENTERING WASHER, CFD
17 HCNS1202 NUT, CFD (½-20 LEFT HAND THREAD – BLUE)
18 EAMU0001 KICKSTART GEAR & SHAFT
19 ECMU0116 SPRING, KICKSTART
20 ZCMUB014 O-RING KICK SHAFT (2 REQ’D)
21 HCWS1622 SHIM, KICK SHAFT
22 ECDC0036 SNAP RING, KICK SHAFT
23 ECDC0046 KICK LEVER W/BOLT & RUBBER
24 HCBF0620 6MM X 20 FLANGE HEAD BOLT
25 ECMU0115 CLUTCH COVER
26 ZCMU0030 CLUTCH COVER GASKET
27 ECMU0037 OIL FILL PLUG
28 ZCMU0005 GASKET, OIL FILL / DRAIN PLUG
29 HCBC0608 6MM X 55 SOCKET HEAD CAP SCREW (6 REQ’D)
30 ECMU0207 KICKSTART GEAR SMALL
31 ECMUSP01 KICK START DOG SPRING (PAPER CLIP)
32 HCWS1016 WASHER – KICK GEAR SPACING
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Parts – Engine – Water Pump
Figure 7C
Engine – Ignition and Water Pump
REF # PART # DESCRIPTION
1 EKMU0001 WATER PUMP KIT
2 ECKG0142 SHAFT, WATER PUMP
3 ECKG0072 BEARING, WATER PUMP
4 ECKG0074 SEAL, WATER PUMP SHAFT
5 ECKG0073 IMPELLER, WATER PUMP (ALUMINUM)
6 ECKG0004 RETAINER, WATER PUMP ASSEMBLY
7 HCBC1512 5X12MM SHCS STAINLESS
9 ECKG0175 WATER PUMP PULLEY, FAN TYPE - DRIVEN
10 ECMU0180 BELT RETAINER
11 HCBS0003 SHOULDER BOLT 6MM
12 ECKG0170 WATER PUMP BELT
13 ECKG0042 WATER PUMP PULLEY, CRANK
14 HCNS1001 NUT 10MM
15 HCBC0408 M4mm x 8 SOCKET HEAD black oxide
16 HCWF0401 4MM WASHER
PIPE GROMMET SPACER (ONLY AVAILABLE IN MCMUGR02
GROMMET KIT)
PIPE GROMMET MALE (ONLY AVAILABLE IN MCMUGR02
GROMMET KIT)
*Parts are included in MCMUGR02 grommet kit.
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Parts - Front A-Arms & Steering Upright
Figure 19
A-arms & steering upright
REF # PART # DESCRIPTION
1 GAEX0001 A-ARM FRONT TOP (SAME PIECE FROM LEFT TO RIGHT)
2 GAEX0002 A-ARM BACK TOP (SAME PIECE FROM LEFT TO RIGHT)
3 GAEX0007 A-ARM FRONT BOTTOM RIGHT
GAEX0006 A-ARM FRONT BOTOTM LEFT
4 GAEX0009 A-ARM BACK BOTTOM RIGHT
GAEX0008 A-ARM BACK BOTTOM LEFT
5 HCBC1065 10MM X 65 SOCKET HEAD CAP SCREW (BLACK OXIDE)
6 MCEXBR05 BUSHING, A-ARM
7 GCEX0006 SPACER, A-ARM PIVOT TUBE
8 HCBF1070 10MM X 70 FLANGE HEAD BOLT
9 HCNL1001 10MM LOCKNUT
10 GAEX0003/4 UPRIGHT WITH SPINDLE, 03 Right, 04 Left
GCEX0032 GREASE FITTING
11 MCEXCL01 SNAP RING, 1-3/8 INTERNAL
12 MCEXBR01 BEARING, SPHERICAL
13 HCBC0806 8MM X 30 SOCKET HEAD CAP SCREW (2 REQ’D)
14 GCEX0009 STEERING ARM
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Parts – Front Brakes (MAGURA)
Figure 20
Front Brakes
REF # PART # DESCRIPTION
1 BAEX0001 FRONT BRAKE ASSEMBLY
2 BKEX0001 HOSE – TEE TO CALIPER
3 BRAKELEVER
4 BCEX0005 BRAKEPERCH&MASTERCYLINDERASSYW/LEVER
5 BCEX0005 CALIPER – FRONT RIGHT
6 BCEX0015 CALIPER – FRONT LEFT
7 BCMU0203 REPLACEMENT BRAKE PADS
8 BCEX0002 BRAKE ROTOR - FRONT (SAME L&R)
9 HCBC0501 M5X16 SHCS (4 REQ’D)
10 BCEX0003R BRAKE CALIPER BRACKET - RIGHT
11 BCEX0003L BRAKE CALIPER BRACKET - LEFT
12 HCBC0612 6MM X 12 SOCKET HEAD CAP SCREW (2 PER SIDE)
13 HCBC0601 6MM X 16 SOCKET HEAD CAP SCREW (3 PER SIDE)
14 WCEX0001 FRONT HUB WITH WHEEL STUDS
16 GCEX0008 WHEEL SPINDLE (SAME L&R)
17 HCNS1400 M14 CASTLE NUT (SAME L&R)
18 HCCP0002 COTTER PIN (SAME L&R)
19 GCEX0022 INNER HUB SEAL (SAME L&R)
FAE50001 MOTOR MOUNT LH 50 QUAD
FAE50002 MOTOR MOUNT RH 50 QUAD
FCEX0039 SPACER, ENGINE MOUNT 50CC RIGHT
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Parts –
Plastic
Bodywork
& Seat
Figure 22
Plastic and Bodywork
REF # PART # DESCRIPTION
1 TCEX0001 FRONT CLIP
NOT SHOWN
NOT SHOWN
NOT SHOWN
NOT SHOWN
NOT SHOWN
NOT SHOWN
NOT SHOWN
2 TCEX0002 REAR DECK
NOT SHOWN
NOT SHOWN
NOT SHOWN
NOT SHOWN
NOT SHOWN
NOT SHOWN
NOT SHOWN
3 TAEX0011 SEAT
NOT SHOWN
NOT SHOWN
NOT SHOWN
NOT SHOWN
4 RCE50002 TANK VENT HOSE
5 TCHA0002 FUEL CAP
6 TCEX0019 FUEL TANK (NO PETCOCK, CAP, OR BRACKET)
7 RCE50001 FUEL LINE
8 TCMU0000 FUEL PETCOCK (’06 LEVER)
9 HCBC0601 M6 X 16 SOC. HEAD BOLT (2 REQ’D)
10 MCMUGR04 GROMMET (2 REQ’D)
11 TCEX0110 FUEL TANK BRACKET
NOT SHOWN
NOT SHOWN
NOT SHOWN
NOT SHOWN
NOT SHOWN
NOT SHOWN
HCBB0616 M6 X 16 BUTTON HEAD (4 REQ’D AT BACK)
HCWF0601 6 MM FLAT WASHER (4 REQ’D AT BACK)
HCBB0625 M6 X 25 BUTTON HEAD (2 REQ’D AT FRONT)
HCWF0601 6MM FLAT WASHER (2 REQ’D AT FRONT)
MCMUGR10 GROMMET, (2 REQ’D AT FRONT)
HCWF1478 WASHER, FENDER (2 REQ’D AT FRONT)
HCNL0601 6MM LOCK NUT (2 REQ’D AT FRONT)
HCBB0625 M6 X 25 BUTTON HEAD (2 REQ’D PLASTIC TO GRAB BAR)
HCWF0601 6MM FLAT WASHER (2 REQ’D PLASTIC TO GRAB BAR)
MCMUGR10 GROMMET, (2 REQ’D PLASTIC TO GRAB BAR)
HCWF1478 WASHER, FENDER (2 REQ’D PLASTIC TO GRAB BAR)
HCNL0601 6MM LOCK NUT (2 REQ’D PLASTIC TO GRAB BAR)
HCBB0616 6MM BUTTON HEAD (2 REQ’D AT FRONT)
HCWF0601 6MM FLAT WASHER (2 REQ’D AT FRONT)
HCBB0635 M6 X 35 BUTTON HEAD (1 REQ’D SEAT TO PLASTIC)
MCMUGR04 GROMMET (1 REQ’D SEAT TO PLASTIC)
HCWF1478 WASHER, FENDER (1 REQ’D SEAT TO PLASTIC)
HCNL0601 6MM LOCK NUT (1 REQ’D SEAT TO PLASTIC)
TCHA0005 TANK MOUNT REAR
HCFH0620 M6 X 20 FLAT HEAD
HCBF0616 M6 X 16 FLANGE HEAD BOLTS (2 REQ’D)
HCBF0620 M6 X 20 FLANGE HEAD BOLT (1REQ’D AT THE REAR)
TCKG0001 SPACER, TANK MOUNT (1REQ’D AT THE REAR)
TCEX2009 GRAPHICS
1 FAEX0002 TIE ROD
2 MCEXBR02R RH TIE ROD END
3 MCEXBR02L LH TIE ROD END
4 HCNJ120L LH JAM NUT
5 HCNJ120R RH JAM NUT
6 GCEX0002 SPACER, BALL JOINT
7 HCNC0010 10MM CASTLE NUT (2 REQ’D)
8 HCCP0003 COTTERPIN 3/32” X ¾” (2 REQ’D)
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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, 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 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
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.
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.
Base Gasket Selection
Tools required
• 17mm wrench
• 1mm flexible solder material
• measurement calipers
When rebuilding the ‘top end’ of your Cobra motorcycle, care must be taken to
ensure the proper squish clearance. Squish clearance is defined as the minimum
distance between cylinder head and piston at TDC, and there are negative
effects of either having too much or too little clearance. Since parts like the crank,
connecting rod, cylinder head, piston, and crankcases all have varying
tolerances, Cobra offers several different base gasket thickness’ to ensure that
you can always set the squish clearance of your engine to factory specifications.
For base gasket replacement use the code (see figure 21 for location) along with
the table on the following page reorder the correct thickness gasket.
Figure 21
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Code Supplied Base
Cobra #
Gasket Thickness
# mm inch Part #
2 0.2 0.008 ZCMU0702
Tolerances will affect the actual gasket thicknesses.
If during the course of the maintenance more parts than the base gasket are
changed, 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 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 ‘smush’ the solder wire.
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.
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Upon completion, your final assembly squish clearance should agree with the
chart below
Engine Removal
To service the bottom end and 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 (#MCMUTL68)
• 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).
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9. Remove the swingarm bolt (22mm 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.
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 (#MCMUTL68), 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 (#MCMUTL68), remove the clutch
from the crankshaft (details 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.
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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.
INSPECTION NOTE:
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.
5. Remove the piston clip with a scribe.
6. Remove the piston pin with a piston pin remover.
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.
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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 28
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9. Torque to 12 Nm (105 in-lb) in the pattern shown in figure 28.
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 29.
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.
Figure 29
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24. Install the water pump outlet pipe (apply Ultra black Hi-Temp RTV silic on
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 30 Figure 31 Clutch puller installation
Tools recommended for clutch service:
• Universal clutch puller- a universal puller that pulls the clutch, main drive gear
and rotor. (Part # MCMUTL70).
1. Drain the engine transmission oil and remove the clutch cover.
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 # PART # DESCRIPTION
1 CAMU0013 Set of three shoes, springs, bolts, flat washers & nuts
2 CAMU0010 Set Of three springs, washers, bolts & nuts
4 HCBS0004 One metric clutch bolt
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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 4 ½ stack.
Stack Total
Springs
Flying Saucers
or Cymbal Pairs
Turned Away
or Dish Stacked
Std. Flat
Washer
5 ½ 11 5 1
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).
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 0.8 0.031
0.9 (0.4 + 0.5) 0.015 + 0.020
1.0 (0.5 + 0.5) 0.020 + 0.020
1.1 (0.6 + 0.5) 0.020 + 0.025
Harder 1.2 0.047
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 # PART NO. DESCRIPT ION
1 ECMU0118 Crank seal
2 ECMU0040 Clutch to hub spacer (standard 0.030” 0.76mm)
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 32)
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 40 ft-lb (54Nm) with the special socket (see figure 33).
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 ECMU0082.
Install the clutch cover tightening the bolts from inside out. (8 or 10 mm socket,
5.8 ft-lb, 7.8 Nm).
INSPECTION NOTE:
a. There must be in / out play in installed clutch, 0.4mm to 1.0 mm
(0.015” to 0.040”).
b. Excess in/out will cause early crank seal failure.
c. 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 (Part # MCMUGF01).
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 0.040” before Top Dead Center
(that means 0.040” 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. (Part # MCMUTL70).
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 0.040” (1.02mm)
from top dead center.
8. Line up the lines on the stator and the rotor (figure 35). Otherwise loosen the
three 5mm bolts to adjust the stator.
0.040”
before
TDC
Figure 35, Lining up the line on the rotor
with the line on the stator.
Figure 36, 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 35).
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
Radiator fluid removal:
Remove the coolant drain plug (13mm bolt) on the front of the engine cases.
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, 2009 King
MCMUTL08, 2009 JR & all older models
• Slide hammer with
• fitting to thread into threads on end of shaft (M5x1.0)
• single and double hook ends for removing plastic impeller
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• 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 41 - 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.
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.
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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 2nd unthreaded hole, the bottom alignment pin is also in
the 2nd unthreaded hole, and that the relief for the stator bolt head is oriented
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.
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).
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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.
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.
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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.
STOCK CARBURETOR SETTINGS
The 2005 KING stock carburetor settings from the factory are:
• 65 pilot jet
• 97 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.
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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 43.
Figure 43 Proper carburetor top
installation and location of
rectangular slide indexing pin and
vent elbows.
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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, it is not necessarily a bad thing, but the pedals may need to be
replaced. (See figure 44) Bikes have been known to run real well with light visible
past the reed tips as long as the jetting proper for the conditions. (See figure 44)
Figure 44
The presence of light may indicate that the reeds should be replaced, or 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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Tuning
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
Mud
Sand
Hills
Hard Pack
Throttle Blipper (novice)
Gear Taller Gear Lower
*
*It may be helpful to set up the clutch to hit early for smooth power delivery
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.
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• 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)
NOTE:
Perform all jetting changes on a motorcycle that has been warmed up to proper
operating temperature.
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The carburetor on your Cobra motorcycle is quite adjustable. Figure 49 shows
its range of adjustment and in particular what adjustable component affects what
range of operation (specifically throttle position).
Figure 49
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
screw driver 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 readjust 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
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 repacking
4) Engine ‘blubbers’ at high RPMs
a) Jetting too rich
5) Engine won’t start
a) Fuel
i) None in tank
ii) Is sour or bad
b) Carburetor is dirty
c) Ignition