Cobra 2009 ECX50 User manual

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For parts orders contact your local dealer
To locate your closest Cobra dealer
log on to
www.cobramotorcycle.com
or call
[phone]
If you need technical assistance
contact your local dealer or call
the Cobra Technical Support Hotline at
[phone]
Cobra Motorcycle MFG., Inc.
240 Uran Road
Hillsdale, MI 49242

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 ECX50 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 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

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Table Of Contents
General Information..............................................................................................5
Specifications - General....................................................................................5
Specifications - Torque Values..........................................................................6
Optional Suspension Components....................................................................7
Spring rate chart for Cobra Fox quad shocks....................................................8
Break-In Procedure...........................................................................................9
Starting Procedure ..........................................................................................10
Maintenance .......................................................................................................11
Tips .................................................................................................................11
Schedule .........................................................................................................11
Replacing Transmission / Clutch Lubricant .....................................................13
Chain adjustment ............................................................................................14
Air Filter Cleaning............................................................................................15
Frictional Drive (CFD)......................................................................................16
Front end.........................................................................................................17
Parts ...................................................................................................................18
Parts – Air Inlet System...................................................................................18
Parts – Bars and Steering...............................................................................19
Parts – Bumper, Nerf & Grab Bars..................................................................20
Parts - Carburetor............................................................................................21
Parts – Coolant System...................................................................................22
Parts – Electrical System ................................................................................23
Parts – Engine – Bottom End and Transmission.............................................24
Parts – Engine Clutch and Kicker................................................................25
Parts – Engine – Water Pump .....................................................................26
Parts – Engine – Top End............................................................................27
Parts – Exhaust System..................................................................................28
Parts - Front A-Arms & Steering Upright .........................................................29
Parts – Front Brakes (MAGURA) ....................................................................30
Parts – Front Brakes (AJP) .............................................................................31
Parts – Front Shock.........................................................................................32
Parts – Miscellaneous.....................................................................................33
Parts – Plastic Bodywork & Seat.....................................................................34

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Parts – Rear Brake..........................................................................................35
Parts – Rear Drive...........................................................................................36
Parts – Rear Shock (Fox)................................................................................37
Parts – Swingarm Assembly............................................................................38
Parts – Tie Rod Assembly...............................................................................39
Service................................................................................................................40
Engine Service................................................................................................40
Base Gasket Selection ................................................................................41
Engine Removal ..........................................................................................43
Complete Engine Disassembly Procedure ..................................................44
Top End Disassembly Procedure ................................................................44
Splitting the Cases.......................................................................................45
Engine assembly .........................................................................................46
Clutch..............................................................................................................48
Ignition.............................................................................................................53
Cooling System...............................................................................................55
Fuel & Air System............................................................................................58
Exhaust ...........................................................................................................61
Tuning.................................................................................................................62
Gearing ...........................................................................................................62
Carburetion .....................................................................................................63

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General Information
Specifications - General
Items ECX50
Dimensions
Wheelbase 42” (1067mm)
Width Front / Rear 43” / 46” (1092mm / 1168mm)
Weight 198lb
Engine
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
Gap 0.023” – 0.025” (0.58 – 0.64 mm)
Ignition timing 0.040” (1.02 mm) BTDC
Fuel type High octane pump gasoline
RACE FUELS ARE NOT RECOMMENDED
Oil type Cobra Venom 2-cycle Race Oil
Fuel / oil mix ratios Between 32:1 and 40:1 (after engine Break-In)
Carburetion 21 mm Dell’Orto PHBG,
Jet Main / Slow (Pilot) 98 / 55
Slide / Needle #30 / W-4
Float Height 16mm + 0.5mm (0.63” + 0.020”)
Transmission
Speed / ratio Single / 14/38 T
Chain 104 links 420
Transmission / clutch oil type Cobra Venom 3 Shoe Clutch Milk
Quantity 235 – 350 ml (8 – 12oz)

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Chassis
Tire Pressure front / rear (7 psi / 5 psi)
Travel, front / rear 240mm / 247mm (9.4” / 9.7”)
Race sag, front / rear 96mm / 99mm (3.8” / 3.9”)
Free sag, front / rear 38mm / 40mm (1.5” / 1.6”)
Specifications - Torque Values
Torque Value
ENGINE Fastener ft-lb in-lb Nm Size &
Remarks
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.

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Torque Value
CHASSIS Fastener 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 13.6 8 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 SCEXA145 (RED, 145 LB/IN)
65 to 100
SCEX1080 (RED,
80 LB/IN) SCEXA155 (YELLOW, 155
LB/IN)
Greater than 100 SCEX1095 (YELLOW,
95 LB/IN) SCEXA165 (BLACK, 165 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)

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Spring Rate (lb/in) Color Part Number
Helper 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
Fox 8” long main
spring (front)
105 Orange SCEX1105
115 Green SCEX1115
125 White SCEX2125
135 Blue SCEX1135
145 Red SCEX1145
155 Yellow SCEX1155
165 Black SCEX1165
Fox 7” long main
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
Venom 2-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).
oClean the carburetor bowl.
oChange the transmission / clutch lubricant.
oReplace 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!