Cobra 2008 ECX50 User manual

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 Street
Hillsdale, Michigan 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.
MCE52007.2

Table Of Contents
General Information..............................................................................................5
Specifications - General....................................................................................5
Specifications - Torque Values..........................................................................6
Optional Suspension Components....................................................................7
Break-In Procedure...........................................................................................8
Starting Procedure ............................................................................................9
Maintenance .......................................................................................................10
Tips .................................................................................................................10
Schedule .........................................................................................................10
Replacing Transmission / Clutch Lubricant .....................................................12
Chain adjustment ............................................................................................13
Air Filter Cleaning............................................................................................14
Frictional Drive (CFD)......................................................................................15
Front end.........................................................................................................16
Parts ...................................................................................................................17
Parts – Air Inlet System...................................................................................17
Parts – Bars and Steering ...............................................................................18
Parts – Bumper, Nerf & Grab Bars..................................................................19
Parts - Carburetor............................................................................................20
Parts – Coolant System...................................................................................21
Parts – Electrical System ................................................................................22
Parts – Engine – Bottom End and Transmission.............................................23
Parts – Engine Clutch and Kicker................................................................24
Parts – Engine – Water Pump .....................................................................25
Parts – Engine – Top End............................................................................26
Parts – Exhaust System..................................................................................27
Parts - Front A-Arms & Steering Upright .........................................................28
Parts – Front Brakes .......................................................................................29
Parts – Front Shock.........................................................................................30
Parts – Miscellaneous.....................................................................................31
Parts – Plastic Bodywork & Seat.....................................................................32
Parts – Rear Brake..........................................................................................33
Parts – Rear Drive...........................................................................................34
3

Parts – Rear Shock (Öhlins)............................................................................35
Parts – Rear Shock (Fox)................................................................................36
Parts – Swingarm Assembly............................................................................37
Parts – Tie Rod Assembly...............................................................................38
Service................................................................................................................39
Engine Service................................................................................................39
Base Gasket Selection ................................................................................40
Engine Removal ..........................................................................................42
Complete Engine Disassembly Procedure ..................................................43
Top End Disassembly Procedure ................................................................44
Splitting the Cases.......................................................................................45
Engine assembly .........................................................................................45
Clutch..............................................................................................................47
Ignition.............................................................................................................52
Cooling System...............................................................................................54
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 Liquid Performance Mini Coolant or Antifreeze
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)
5

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 35 420 47 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.
6

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 White 460 lb/in
(SCEX1460)
50 to 75 Gold 500 lb/in
(SCEX1500)
Greater than 75 Green 530 lb/in
(SCEX1530)
7

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
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.
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!
8

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 Venom 2-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.
9