Cobra 2008 ECX70 Service Manual
For parts orders contact your local dealer
To locate your closest Cobra dealer
log on to
www.cobramotorcycle.com
or call
(517) 437-9100
If you need technical assistance
contact your local dealer or call
the Cobra Technical Support Hotline at
(517) 437-9100
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 ECX70 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.
MCE72007 2
Table Of Contents
General Information..............................................................................................3
Specifications - General....................................................................................3
Specifications - Torque Values..........................................................................4
Optional Suspension Components....................................................................5
Starting Procedure ............................................................................................8
General Tips......................................................................................................9
Maintenance .......................................................................................................10
Schedule & Tips..............................................................................................10
M1: Replacing Transmission Lubricant ...........................................................10
M2: Chain adjustment .....................................................................................11
M3: Air Filter Cleaning.....................................................................................12
M4: Front end..................................................................................................14
Toe in adjustment........................................................................................14
Steering .......................................................................................................14
Parts ...................................................................................................................15
Parts – Air Inlet System...................................................................................15
Parts – Bars and Steering ...............................................................................16
Parts – Bumper, Nerf & Grab Bars..................................................................17
Parts – Carburetor...........................................................................................18
Parts – Clutch Actuation..................................................................................19
Parts – Coolant System...................................................................................20
Parts – Electrical System ................................................................................21
Parts – Engine Clutch......................................................................................22
Parts – Engine – Clutch / Kick Cover...........................................................23
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Parts - Engine - Ignition Side.......................................................................24
Parts - Engine – Kick Mechanism................................................................25
Parts – Engine – Shift Mechanism...............................................................26
Parts – Engine – Top End............................................................................27
Parts - Engine - Transmission......................................................................28
Parts – Exhaust System..................................................................................29
Parts - Front A-Arms & Steering Upright.........................................................30
Parts – Front Brakes .......................................................................................31
Parts – Front Shock.........................................................................................32
Parts – Miscellaneous.....................................................................................33
Parts – Plastic Bodywork & Seat.....................................................................34
Parts – Rear Brake..........................................................................................35
Parts – Rear Drive...........................................................................................36
Parts – Rear Shock.........................................................................................37
Parts – Swingarm Assembly............................................................................38
Parts – Tie Rod Assembly...............................................................................39
Engine Parts / Service ........................................................................................40
Engine Service................................................................................................40
Base Gasket Selection ................................................................................41
Fuel & Air System............................................................................................43
Reeds ..........................................................................................................43
Carburetor Cleaning ....................................................................................44
Exhaust ...........................................................................................................45
Tuning.................................................................................................................45
Carburetor.......................................................................................................45
Jetting Decisions..........................................................................................45
Troubleshooting..................................................................................................48
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General Information
Specifications - General
Items ECX70
Dimensions
Wheelbase 42” (1067mm)
Width Front / Rear 43” / 46” (1092mm / 1168mm)
Weight 210 lb
Engine
Type 2-stroke, single cylinder, reed valve
Cooling system Liquid-cooled
Displacement 64.8 cc (3.95 Cubic inches)
Bore and stroke 44.5 mm x 44.7 mm
Ignition system Digital Electronic
Spark plug Champion 8339
Gap 0.023” – 0.025” (0.58 – 0.64 mm)
Fuel type 93 octane pump gasoline
Oil type
Fuel / oil mix ratios 32:1
Ignition timing .050” (1.3mm) BTDC
Carburetion 26mm Mikuni VM
Main jet 190
OTHER RACE FUELS ARE NOT RECOMMENDED
Cobra Venom 2-cycle Race Oil
Slow (Pilot) jet 50
Jet needle 5F21, 4th position from the top
Float height
Transmission
Speed Six speed
Clutch Manual hydraulic
Final drive ratio 13/48 T
Transmission / clutch oil type
Cobra Power Shift Transmission Lubricant
Quantity 530 ml (18 oz)
3
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
ENGINE Fastener
Torque Value
ft-lb in-lb Nm
Size &
Remarks
Cylinder head nuts 14 170 19 7mm
Engine oil drain 3 36 4 8 x 1.25
Engine oil fill 2 24 2.7 14 x 1.0
Spark Plug (SP) (SP) (SP) 14 x 1.25
Crank case half 5 60 6.8 6 x 1.0
Crank case cover 5 60 6.8 6 x 1.0
Flywheel rotor nut 40 480 54 10 x 1.25 (G)
Clutch hub 40 480 54 10 x 1.25 (G)
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.
4
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 13.6 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 or
green) 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
Rear shock springs
Weight of Rider (lb) Helper Main
Less than 65
65 to 100
Greater than 100
SCEX0065P (SILVER,
65 LB/IN)
SCEX1080 (RED, 80
LB/IN)
SCEX1095 (YELLOW,
95 LB/IN)
SCEX1150 (GREEN,
150 LB/IN)
SCEX0175P (BLACK,
175 LB/IN)
SCEX0200P SILVER
(200 LB/IN)
SCEXA135 (BLUE, 135 LB/IN)
SCEXA145 (RED, 145 LB/IN)
SCEXA155 (YELLOW, 165
LB/IN)
SCEX025P (BLUE, 425 LB/IN)
SCEX0450P (GREEN, 450 LB/IN)
SCEX0475P (BLACK, 475 LB/IN)
Spring Rate
Helper
Color Part Number
(lb/in)
65 Silver SCEX0065P
5
Fox 8” long main
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
Spring rate chart for Cobra Fox quad shocks
6
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 ECX70
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 MO2
, with Cobra’s specially formulated Cobra
X
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 in neutral with a combination of idle
and high RPM operation. (avoid prolonged high RPM rev it 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 with Cobra Power Shift
Transmission 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!
7
Starting Procedure
Before starting the machine inspect the following:
• Insure that the fuel tank contains an adequate volume of fuel / oil mixture to
complete the distance required. (93 octane pump gas with Cobra’s specially
formulated Cobra Venom 2-cycle Race Oil)
• Check for proper tire pressure in both tires.
• Observe the chain tension and adjust if necessary.
• Observe the coolant level and fill if necessary.
• Observe the level of lubricant in the transmission and add Cobra Power
Shift Transmission Lubricant if necessary.
• Verify that the chain rollers do not have improper wear.
• Inspect the frame, for;
o Cracks in the metal.
o Cracking paint which might indicate overly stressed material.
• Verify that the handlebars are tight.
• Check the throttle for;
o Smooth operation and sound closing.
o Frayed strands of the cable inside the throttle housing.
• Check for loose bolts and nuts, and re-torque as necessary.
• Verify that the air filter is clean and properly saturated with oil.
• Turn the fuel on by rotating the fuel petcock knob to the vertically downward
position (reserve position is horizontally inward).
CAUTION:
For best results from your Cobra ATV use only the recommended fuels. Testing
has shown that most ‘race’ fuels actually degrade performance.
When your pre-ride inspection is complete the bike may be started. For a cold
engine follow this procedure.
1. Reaching down to the carburetor, on the left side of the bike, push down on
the black choke lever.
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. 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. Make sure your
engine is properly warmed up before racing.
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General Tips
1. Always wear a helmet and other protective riding gear.
2. 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.
3. Make sure your riders’ foot is not resting on the rear brake pedal while they
are riding
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. When washing the bike, be careful to not directly aim the hose at the air
filter area.
7. Mare sure that there is adequate free play in both the front lever and rear
brake pedal.
8. Your Cobra ATV has a 10 digit VIN (Vehicle Identification Number). The
first three digits indicate the model and the seventh indicates the model
year (MY).
.
a. Example, ECXxxx7xxx is a 2007 MY ECX70.
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Maintenance
Schedule & Tips
It is important that you adhere to this maintenance schedule so as to promote the
longevity of your Cobra Motorcycle.
• Between each ride
o Inspect the fuel filter for contaminates.
o Check the air filter (clean and re-oil as necessary).
o Insure the smooth operation of the throttle cable (throttle soundly
‘clacks’ shut).
o Check 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 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.
• Every 2 hours of operation
o Replace the transmission oil with Cobra Power Shift Transmission
Lubricant.
• Every 10 hours of operation
o Have the shock oil replaced by a Certified Cobra Mechanic.
CAUTION:
1. 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.
2. The frame is a low carbon alloy tubing 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.
M1: Replacing Transmission Lubricant
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Tools needed:
• 530 ml (18 oz) Cobra Power Shift Transmission Lubricant
• large flat blade screwdriver
• 13 mm wrench or socket
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 ‘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. Using the 13 mm wrench, remove the oil drain bolt located on the right side
of the engine (figure 1).
4. After it has drained, reinstall the drain screw with gasket.
5. Remove the oil fill plug and pour in 530 ml (18 oz) 85W 90 gear lubricant.
NOTE: Leaning the bike over onto it’s left hand side will facilitate the oil filling
procedure.
6. Reapply the oil fill screw, securely, being sure the gasket is in place.
M2: Chain adjustment
Tools needed:
Figure 1
11
• 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).
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.
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.
Figure 1
M3: Air Filter Cleaning
This Cobra Motorcycle comes with a unique air filter / air boot unit designed to
facilitate motorcycle service.
12
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.
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.
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