Cobra CX65 User manual

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DISCLAIMER OF WARRANTY
This motorcycle is sold “as is” with all faults, obvious or not. There are no warranties
expressed or implied, including any warranty of merchantability and warranty of fitness
for any particular purpose.
“WARNING”
THE COBRA CX65 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 110 LBS WITH
FULL RIDING GEAR AND SHOULD NOT BE OPERATED BY RIDERS THAT WEIGH
MORE THAN THAT.
BE SURE THAT THE RIDER ALWAYS WEARS ADEQUATE SAFETY GEAR
EVERYTIME HE OR SHE RIDES THEIR COBRA MOTORCYCLE.
IMPORTANT SAFETY NOTICE
Failure to follow WARNING instructions could result in severe injury or death to
the machine operator, a bystander, or a person inspecting or repairing the
machine.
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.
MCC62014.V1

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Table of Contents
GENERAL INFORMATION..........................................................................................4
SPECIFICATIONS -GENERAL............................................................................................. 4
OPTIONAL COMPONENTS ................................................................................................. 5
SPECIFICATIONS -TORQUE VALUES................................................................................. 5
BREAK-IN PROCEDURE .................................................................................................... 6
STARTING PROCEDURE .................................................................................................... 6
MAINTENANCE ...........................................................................................................7
TIPS ................................................................................................................................. 7
SCHEDULE........................................................................................................................ 8
REPLACING TRANSMISSION /CLUTCH LUBRICANT .......................................................... 9
CHAIN ADJUSTMENT ...................................................................................................... 10
AIR FILTER CLEANING................................................................................................... 11
FORK MAINTENANCE..................................................................................................... 11
Fork Air Bleeding ..................................................................................................... 12
Fork Oil Replacement............................................................................................... 12
IGNITION TIMING ........................................................................................................... 14
CABLE TIES.................................................................................................................... 14
PARTS........................................................................................................................16
PARTS –AIRBOX &INLET SYSTEM................................................................................ 16
PARTS –BARS AND CONTROLS ...................................................................................... 17
PARTS -CARBURETOR ................................................................................................... 18
PARTS –CLUTCH –MASTER CYLINDER......................................................................... 19
PARTS –COOLANT SYSTEM ........................................................................................... 20
PARTS –ELECTRICAL SYSTEM....................................................................................... 21
PARTS –ENGINE CLUTCH .............................................................................................. 22
PARTS –ENGINE –CLUTCH /KICK COVER .................................................................... 23
PARTS –ENGINE –IGNITION SIDE.................................................................................. 24
PARTS –ENGINE –KICK MECHANISM............................................................................ 25
PARTS –ENGINE –SHIFT MECHANISM........................................................................... 26
PARTS –ENGINE –TOP END .......................................................................................... 27
PARTS –ENGINE –POWER VALVE ................................................................................. 28
PARTS –ENGINE –TRANSMISSION................................................................................. 29
PARTS –EXHAUST SYSTEM............................................................................................ 30
PARTS –FORKS &TRIPLE CLAMPS................................................................................ 31
PARTS –FORK –LEG ASSEMBLY –BRAKE SIDE............................................................ 32
PARTS –FORK –LEG ASSEMBLY –NON-BRAKE SIDE ................................................... 33

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PARTS –FRAME ............................................................................................................. 34
PARTS –FRONT WHEEL ................................................................................................. 35
PARTS –FRONT BRAKES –MASTER CYLINDER ............................................................. 36
PARTS –FRONT BRAKES –CALIPER............................................................................... 37
PARTS –BODYWORK ..................................................................................................... 38
PARTS –REAR BRAKE.................................................................................................... 39
PARTS –REAR WHEEL................................................................................................... 40
PARTS –SHOCK EXTERNAL ........................................................................................... 41
PARTS –SHOCK –INTERNAL.......................................................................................... 42
PARTS –SWINGARM ASSEMBLY .................................................................................... 43
SERVICE....................................................................................................................44
ENGINE SERVICE............................................................................................................ 44
Base Gasket Selection............................................................................................... 45
Power Valve.............................................................................................................. 47
EXHAUST ....................................................................................................................... 48
FUEL &AIR SYSTEM...................................................................................................... 48
CARBURETOR:................................................................................................................ 48
REAR SHOCK.................................................................................................................. 50
BRAKES ......................................................................................................................... 50
Rear Brakes............................................................................................................... 50
Front Brakes ............................................................................................................. 51
FRONT WHEEL............................................................................................................... 52
Assembly ................................................................................................................... 52
TUNING......................................................................................................................53
GEARING........................................................................................................................ 53
SUSPENSION................................................................................................................... 54
Adjustment:............................................................................................................... 54
Front Fork Operation............................................................................................... 54
Fork Damping Adjustments ...................................................................................... 55
Rear Shock Adjustments............................................................................................ 56
CARBURETOR................................................................................................................. 57
TROUBLESHOOTING ...............................................................................................60
INDEX.........................................................................................................................62

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General Information
Specifications - General
Items
CX65
Dimensions
Wheelbase
40.9” (1040mm)
Wheel size
12” (305mm) rear, 14” (356mm) front
Seat height
29.9” (760mm)
Engine
Type
2-stroke, single cylinder, reed valve
Cooling system
Liquid-cooled
Coolant
50/50 antifreeze-coolant / distilled water
Displacement
64.9 cc
Bore and stroke
44.5 mm x 41.7 mm
Ignition system
Electronic, digital advance
Spark plug
Autolite 4063 or XS4063
Gap
0.024” –0.026” (0.60 –0.65 mm)
Ignition timing
Digital advance (set at “0” timing mark)
Fuel type
High octane pump gasoline
Premix Oil type
Bel-Ray H1-R
Premix oil ratio after break-in
40:1 –50:1
Carburetion
26 mm VM Mikuni
Main Jet / Slow (Pilot) Jet
280 / 42.5
Needle
5I 14 - 4
Float Height
21.1 ± 1.0
Transmission
6 speed
Final drive ratio
14/45
Chain
116 links 420
Transmission / clutch oil type
Quality gear lubricant, or Cobra clutch milk
Do Not Run Automotive Motor Oil
Quantity
530 ml (18.0oz)
Chassis
Front tire
60/100 –14
Rear tire
80/100 –12
Front fork
CARD 37mm USD, Fully adjustable
Fork oil type
SAE 2.5 WT
Fork oil amount
250 ml (8.5oz)
Adjustments (turns out)
Compression 5/8, Rebound 2 1/2, Bottoming 2 3/4
Rear shock (clicks out)
Compression Low 9, High 8, Rebound 26
Race sag 87mm

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Optional Components
Weight of Rider (lb)
Fork Spring
Shock Spring
less than 70 lb
0.24 kg/mm
KCC63724
42 N/MM (240 lb/in)
SCC60240P (white)
75-85 lb
0.26 kg/mm
KCC63726
45 N/MM (260 lb/in)
SCC60260PY stock (yellow)
85-100 lb
0.28 kg/mm
KCC63728
49 N/MM (280 lb/in)
SCC60280PG (gold)
Ohlins #
00281-44/50 L078
Greater than 100
53 N/MM (300 lb/in)
SCEX1300 (red)
Specifications - Torque Values
Fastener
Torque Value
Size & Remarks
ft-lb
in-lb
Nm
Cylinder head nuts
9
110
12
M6 x 1.0
Cylinder nuts
22
265
30
M8 x 1.25**
Crankcase bolts
9
110
12
M6 x 1.0
PV Jam Nut
6
72
8
M6 x 1.0**
PV Cap Screws
3
35
4
M5 x 0.8
Exhaust Flange
5
60
6
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
Front axle bolt
33
400
45
M20 x 1.0
Front axle pinch bolt
8.8
106
12
M6 X 1.0
Front brake rotor
7.4
88.5
10
M6 x 1.0
Engine mount bolts
22
265
30
M8 X 1.25
Swingarm pivot
21
250
28
M12 X 1.5
Intake manifold bolts
4.6
55
6.2
M6 X 1.0
Rear axle
25
300
34
M14 X 1. 5
Rear sprocket
20
240
27
M8 X 1.25
Rear brake rotor
7.4
88.5
10
M6 x 1.0
Triple clamp (top)
9
108
12
M6 x 1.0
Triple clamp (bottom)
6
72
8
M6 x 1.0
Fork cap
15
177
20
Fork Damper Nut
11
133
15
Ignition rotor nut
33
400
45
M10 x 1.25*
* Apply high strength thread locking agent when installing
** Use a ‘crows foot’ attachment oriented 90° to the torque wrench
(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.

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Break-In Procedure
Your Cobra CX65 is a close-tolerance high performance machine and break-in
time is very important for maximum life and performance. The CX65 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.
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).
Cool and inspect bike for loose fasteners.
Check & retighten wheel spokes
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).
oClean the carburetor bowl.
oChange the transmission / clutch lubricant.
After 8 hours of operation
oChange the fork oil.
oHave a Certified Cobra Mechanic change the shock oil.
Your bike is now ready for the highest level of competition!
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.

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Insure that the fuel tank contains an adequate volume of fuel / oil mixture to
complete the distance required.
Turn the fuel on by rotating the fuel petcock lever to the vertically downward
position.
CAUTION:
For best results from your Cobra Motorcycle use only the recommended fuels.
‘Race’ fuels can be used, however, they are not required with the stock engine,
and the engine will require addition attention to maintain proper jetting as
weather condition change throughout the day.
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. Engage the choke by pulling out on the choke button until it stops.
3. Kick start the engine.
4. Rev the engine in short spurts, turning the throttle no more than 1/4 open
until the engine will run without the choke.
5. Verify a functional engine shut-off switch by shutting off the engine.
6. Restart the engine and proceed with riding when the engine is sufficiently
warm (i.e. the side of the cylinder is warm to touch).
CAUTION:
Never rev an engine full throttle when it's cold or slightly warmed up. This may
lead to premature wear of engine components or complete cold seizure of the
engine.
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.
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. Use only high quality transmission oil designed specifically for two-
stroke racing engines.
b. Bel-Ray H1-R oil is the recommended premix oil:

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2. Fill your transmission only with the recommended amount of oil. Overfilling
may lead to premature seal failure.
3. The cylinder base gasket has been ‘fitted’ for your engine. See the service
section of this manual for instructions how to properly size a base gasket
during an engine rebuild.
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, CXxxxx7xxx is a 2007 MY CX65.
Schedule
Prior to each ride
oCheck the air filter (clean and re-oil as necessary).
oInsure the smooth operation of the throttle cable (throttle soundly
‘clacks’ shut).
oCheck for frayed strands of the throttle cable inside the throttle housing
and replace if necessary.
oCheck for adequate tire pressures and adjust if necessary.
oCheck all nuts and bolts for proper torque and re-torque if necessary.
oCheck drive chain for
Proper tension and adjust if necessary.
Adequate lubrication and lubricate if necessary.
oInsure that the ignition stator and rotor are clean and dry.
oCheck 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.
Replace or get properly re-welded as necessary.
oCheck the spokes for tightness and adjust if necessary.
oCheck the rims and hubs for signs of stress, like cracks around the rim,
spokes and hub.
oEqualize the pressure in the forks with atmosphere.
oCheck for adequate brake operation and pad thickness
Every 2 hours of operation
oReplace the transmission oil.
oCheck spoke tension
Every 10 hours of operation
oReplace the fork oil.
oHave the shock oil replaced by a Certified Cobra Mechanic.
Every 15 hours
oReplace piston rings
Inspect piston for wear and cracks.
oClean the power valve (no adjustment necessary)
oInspect the power valve cable.

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CAUTION:
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.
The frame is a combination of HSLA steel and 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.
Replacing Transmission / Clutch Lubricant
Tools needed:
18 oz, of high quality transmission oil, or Cobra clutch milk
8 mm Allen wrench
CAUTION:
General automotive motor oil has frictional modifiers which will cause premature
wear and failure of the clutch.
Procedure:
1. Begin this procedure with a bike that has been ridden more than 5 minutes
but less than 10 minutes. It is desired to have the engine warm enough so
that the oil is ‘runny’ but not so hot that there is risk of being burned by the
engine or the oil.
Hot oil and hot components on the
motorcycle may cause burns.
2. Lean the bike against something or
set on stand with oil drain hole.
3. Using a 8mm Allen wrench, remove
the oil drain bolt located on the
right side of the engine, on the
clutch cover, near the brake lever
(See Figure 1).
NOTE: You may need to adjust the
brake pedal (up or down) to gain
access to the drain bolt.
Figure 1

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4. After it has drained, reinstall the bolt being sure that the rubber gasket is in
place. Torque to 11 Nm (8 ft-lb).
5. Remove oil fill plug with an 8mm Allen wrench.
6. Carefully pour 16 oz (470 ml) of transmission oil into the oil fill opening.
7. Reinstall the oil fill plug making sure the rubber gasket is in place.
NOTE: Filling after an engine rebuild required additional transmission fluid. If the
engine is completely flushed of oil, refill with 18 oz (530ml).
Always capture and dispose of used oil properly (all auto parts stores accept
used oil). Dumping oil on the ground is illegal, inconsiderate, and can get you
disqualified from a race weekend quicker than cutting the track.
Chain adjustment
Tools required for chain adjustment
22 mm wrench or socket
2 - 11 mm open-end wrenches
1. Make sure that the rear wheel is aligned
properly.
2. For proper adjustment, the chain should
have 35 mm free movement just behind
the chain block with no load on the bike
(Figure 2)
CAUTION:
Sit on the bike and verify that the chain has a minimum of 12mm (1/2”) free
movement when the chain is at its tightest point.
3. If the chain requires adjusting, loosen the axle
with a 22mm wrench, and loosen the jam nut with
an 11mm wrench. Tighten the chain by rotating
the adjustor bolts clockwise (CW) or loosen the
chain by rotating the adjustor bolts (CCW).
4. Put a rag between the sprocket and chain, and
roll the wheel backward to pull the chain adjustor
blocks tightly against the adjustor bolts (Figure
3).
5. Retighten the axle bolt to 25 ft-lb (34 Nm).
6. Retighten the adjustor jam nuts.
CAUTION:
Always check rear brake adjustment and free-play after adjusting the chain.
Figure 3.
Figure 2
Figure 3