Cobra Moto CX50 FWE User manual

F
Owners
Parts
Service
Tuning

2
For parts orders, contact your local dealer.
To locate your closest Cobra dealer, log on to
www.cobramoto.com
or call
+1 (517) 437 - 9100
Cobra MOTO, LLC
240 Uran Road
Hillsdale, MI 49242
USA

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 CX50FWE (KING) IS A COMPETITION MODEL ONLY AND IS NOT MANUFACTURED
FOR, NOR SHOULD IT BE USED ON PUBLIC STREETS, ROADS OR HIGHWAYS.
THE USE OF THIS BIKE SHOULD BE LIMITED TO PARTICIPATION IN SANCTIONED
COMPETITION EVENTS UPON A CLOSED COURSE BY A SUFFICIENTLY SKILLED RIDER AND
SHOULD NOT BE USED FOR GENERAL OFF-ROAD RECREATIONAL RIDING.
IMPROPER USE OF THIS MOTORCYCLE CAN CAUSE INJURY OR DEATH.
THIS BIKE IS INTENDED FOR EXPERIENCED RACERS ONLY AND NOT FOR BEGINNERS.
IT IS YOUR RESPONSIBILITY AS THE OWNER OF THIS COBRA MOTORCYCLE OR AS THE
PARENT, OR LEGAL GUARDIAN OF THE OPERATOR, TO KEEP THIS COBRA MOTORCYCLE IN
PROPER OPERATING CONDITION.
THIS BIKE WAS DESIGNED FOR RIDERS THAT WEIGH LESS THAN 80 LBS WITH FULL RIDING
GEAR AND SHOULD NOT BE OPERATED BY RIDERS THAT WEIGH MORE THAN THAT.
BE SURE THAT THE RIDER ALWAYS WEARS ADEQUATE SAFETY GEAR EVERYTIME HE OR
SHE RIDES THEIR COBRA MOTORCYCLE.
IMPORTANT SAFETY NOTICE
Failure to follow WARNING instructions could result in severe injury or death to the machine
operator, a bystander, or a person inspecting or repairing the machine.
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.
MCCS2021FWE.3

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Table of Contents
GENERAL INFORMATION ..................................................................................................... 4
SPECIFICATIONS - GENERAL ........................................................................................................................ 4
OPTIONAL SUSPENSION COMPONENTS ........................................................................................................ 5
SPECIFICATIONS - TORQUE VALUES ............................................................................................................ 6
BREAK-IN PROCEDURE ............................................................................................................................... 8
STARTING PROCEDURE ............................................................................................................................... 9
MAINTENANCE ....................................................................................................................... 10
TIPS ......................................................................................................................................................... 10
SCHEDULE ............................................................................................................................................... 11
REPLACING TRANSMISSION / CLUTCH LUBRICANT ...................................................................................... 12
PROPER CHAIN ADJUSTMENT .................................................................................................................... 13
REAR BRAKE MAINTENANCE ..................................................................................................................... 14
FORK MAINTENANCE................................................................................................................................. 16
Fork Air Bleeding................................................................................................................................ 16
Fork Oil Replacement ........................................................................................................................ 17
DISASSEMBLY PROCEDURE ....................................................................................................................... 17
FRICTIONAL DRIVE (V3 CFD) .................................................................................................................... 18
PARTS – AIRBOX & INLET SYSTEM ............................................................................................................. 20
PARTS – BARS AND CONTROLS ................................................................................................................. 21
PARTS – CARBURETOR ............................................................................................................................. 22
PARTS – COOLANT SYSTEM ...................................................................................................................... 23
PARTS – ELECTRICAL SYSTEM .................................................................................................................. 24
PARTS – ENGINE – BOTTOM END AND TRANSMISSION ................................................................................ 25
PARTS – ENGINE CLUTCH AND KICK LEVER ............................................................................................... 28
PARTS – ENGINE – WATER PUMP .............................................................................................................. 30
PARTS – ENGINE – TOP END ..................................................................................................................... 31
PARTS – FORKS & TRIPLE CLAMPS ........................................................................................................... 34
PARTS – FORKS – LEG ASSEMBLY – BRAKE SIDE ....................................................................................... 36
PARTS - FORKS – LEG ASSEMBLY – NON-BRAKE SIDE ................................................................................ 38
PARTS – FRAME I ..................................................................................................................................... 40
PARTS – FRAME II .................................................................................................................................... 41
PARTS – FRONT BRAKES .......................................................................................................................... 42
PARTS – FRONT WHEEL ............................................................................................................................ 43
PARTS – PLASTIC BODYWORK & SEAT ....................................................................................................... 44
PARTS – REAR BRAKE .............................................................................................................................. 46

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PARTS – REAR WHEEL ............................................................................................................................. 48
PARTS – SHOCK ....................................................................................................................................... 49
PARTS – SHOCK - INSIDE .......................................................................................................................... 50
PARTS – SWINGARM ASSEMBLY ................................................................................................................ 51
SERVICE .................................................................................................................................... 52
ENGINE SERVICE ...................................................................................................................................... 52
Base Gasket Selection....................................................................................................................... 53
CFD Adjustment................................................................................................................................. 55
Engine Removal................................................................................................................................. 55
Complete Engine Disassembly Procedure ........................................................................................ 56
Top End Disassembly Procedure ...................................................................................................... 56
Splitting the Cases............................................................................................................................. 57
Engine assembly................................................................................................................................ 58
CLUTCH ................................................................................................................................................... 59
Clutch Assembly: ............................................................................................................................... 62
IGNITION .................................................................................................................................................. 63
COOLING SYSTEM .................................................................................................................................... 64
FUEL & AIR SYSTEM ................................................................................................................................. 65
Carburetor:......................................................................................................................................... 65
Reeds:................................................................................................................................................ 67
EXHAUST ................................................................................................................................................. 67
REAR WHEEL PULLERS .............................................................................................................................. 68
BRAKES ................................................................................................................................................... 68
FRONT FORKS .......................................................................................................................................... 68
REAR SHOCK ........................................................................................................................................... 69
TUNING ...................................................................................................................................... 69
CLUTCH ................................................................................................................................................... 69
GEARING .................................................................................................................................................. 71
Front Fork Operation.......................................................................................................................... 73
Fork Damping Adjustments................................................................................................................ 73
Rear Shock Adjustments ................................................................................................................... 74
CARBURETION .......................................................................................................................................... 75
TROUBLESHOOTING ........................................................................................................... 78
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General Information
Specifications - General
Items CX50 FWE
Dimensions
Wheelbase 41” (1041mm)
Wheel size 10” (254mm) rear, 12” (305mm) front
Seat height 26” (660mm)
Engine
Type 2-stroke, single cylinder, reed valve
Cooling system Liquid-cooled
Coolant Spectro Year-Round Super Coolant
Displacement 49.8 cc
Bore and stroke 39 mm x 41.7 mm
Ignition system PVL Analogic
Spark plug – XS61 AUTOLITE, RN6YC & 8339 CHAMPION
Gap 0.023” – 0.025” (0.58 – 0.64 mm)
Ignition timing 0.035” (0.9 mm) Before Top Dead Center (BTDC)
Fuel type High octane pump gasoline
Premix Oil type Spectro Platinum SX
2
Premix oil ratio after break-in 32:1
– 60:1
Carburetion 19 mm Dell’Orto
Slow (Pilot) Jet / Main Jet 55 / 93
Needle W7-2
Needle Clip Position 2
nd
slot from top of needle
Float Height 16mm + 0.5mm (0.63” + 0.020”)
Transmission
Speed Single
Final drive ratio 15/38 T
Chain 102 links 420
Transmission / clutch oil type Cobra Venom 3 Shoe Clutch Milk
Quantity 300cc (10oz)
Chassis
Front tire 2.50 (60/100) - 12"
Pressure 16 psi minimum
Rear tire 2.75 (80/100) - 10"
Pressure 16 psi min. (20 psi for hard pack or rocky conditions)
Front fork CARD 32mm USD Fully Adjustable w/ Smart Leg
Fork oil type 5wt Spectro Fork Oil
Fork oil amount 150 ml
Std settings (turns) Smart leg: 1.5 out, Compression and rebound 2 out
Rear shock (std. settings) Compression: Low 12 clicks out, High 15 clicks out
Rebound 16 clicks out, Race sag 75mm, Free sag

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Optional Suspension Components
Weight of Rider (lb) Fork Spring Shock Spring
Less than 50 lb 0.23 kg/mm
KCCS3223
green, 2.9 kg/mm
SCKGFX29
50-60 0.25 kg/mm
KCCS3223
black, 3.1 kg/mm
SCKGFX31
60-75 0.25 kg/mm
KCCS3225
red, 3.3 kg/mm
SCKGFX33
Greater than 80 0.27 kg/mm
KCCS3227
gray, 3.5 kg/mm
SCKGFX35

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Specifications - Torque Values
Fastener Torque Value Loctite TM 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 See the next page M6 x 1.0
Spark plug (SP) (SP) (SP) M14 x 1.25
Stator bolts 2.1 25 2.8 M5 X 0.8
Ignition rotor nut 30 400 45 243 M10 x 1.25
Stator cover bolts 1.7 20 2.3 243 M4 X 0.75
Clutch cover bolts 5.8 70 7.9 M6 X 1.0
Clutch nut 40 480 54 263 M10 x 1.25
Clutch bolts 12 144 16 263 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 47 243 M10 x 1.5
Water pump impeller 3 36 4 263 M5 x 0.8
Water pump pulley 10 124 14 243 M6 x 1.0
Intake manifold bolts 4.6 55 6.2 M6 X 1.0
Rear axle nuts 21 250 28 M12 X 1.25
Rear sprocket bolts 21 250 28 M7 X 1.0
Front axle aluminum bolt 18 221 25 Moly lube M10 X 1.25
Fork guard alum bolts 6 88 8 243 M6X1, ALUM
Front axle pinch bolts 7.5 88 10 M6 x 1.0
Brake caliper bolts 9 106 12 243 M6 x 1.0
Brake caliper to carrier 7 84 9.5 243 M6 x 1.0
Brake pad secure 3 36 4 M5 x 0.8
Banjo bolts – brakes 15 177 20 M8 x 1.25
Brake rotor bolts 9 108 12 243 M5 x 0.8
Triple clamp bolt (top) 8 90 10 M8 x 1.25
Steering stem pinch bolt 9.5 115 13 M8 x 1.25
Triple clamp bolts (bottom) 6 72 8 M6 x 1.0
** 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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Proper case bolt torque values
Torque the engine case bolts in the pattern shown above. The upper two bolts have a different
toque value compared to the others.
Proper torquing procedure would have you lubricating the threads with 30W oil, torquing the
bolts all first to an intermediate torque value of 10-12 Nm and then once they are all at that
value, proceed back at bolt #1 and toque each bolt further up to the final value.

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Break-In Procedure
Your Cobra CX50 FWE King is a close-tolerance high performance machine and break-in time
is very important for maximum life and performance. The CX50 can be ridden hard after the first
½ hour break-in time.
Cobra recommends Spectro Platinum SX
2
premix oil with high octane
pump gas mixed at 32:1 (4 oz oil to a gallon of gas).
CAUTION: Failure to use proper fuel, oil, or fuel/oil mixture may result in premature engine
wear or damage to the machine.
Adhering to the following break-in schedule will result in long lasting high performance machine.
 Start bike on stand
 First 5 minute period, operate the bike on the stand with a combination of idle and high
RPM operation. (avoid prolonged high RPM but spin the rear wheel good at least once or
twice per minute)
 Allow bike to cool
 Ride for 15 minutes maximum (avoid prolonged high RPM operation and avoid abusing the
clutch with throttle blipping.
 Cool and inspect bike for loose fasteners.
 Next ½ hour of operation, avoid prolonged operation at Wide Open Throttle.
 After 1 hour of operation
o Check for loose bolts and nuts on the bike and retighten as necessary (proper toque
values are listed under Specifications).
o Clean the carburetor bowl.
o Change the transmission / clutch lubricant.
 Check CFD torque and adjust as necessary
 After 8 hours of operation
o Change the fork oil.
o Have a Certified Cobra Mechanic change the shock oil.
 Your bike is now ready for the highest level of competition!
NOTE: During break-in the bike will likely lose some engine coolant through the radiator
overflow hose. Losing up to 4 oz (120 ml, ½ cup) is normal. Proper coolant level is to the
bottom of the filler neck. Removing the radiator cap and looking inside is the only way to check
the coolant level.
Never open the radiator cap of a machine that has a hot or warm engine or one that has recently
been ridden. Burning and scalding could occur.