Cobra 2006 ECX70 User manual

ECX70
Owners
Parts
Service
Tuning

1
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.
11511 Springfield Road
North Lima, Ohio 44452 MCEX2006.3

2
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 ACOMPETITION 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 TOPARTICIPATION IN SANCTIONED
COMPETITION EVENTS UPON A CLOSED COURSEBY 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 RESPONSIBILITYAS THE OWNER OF THIS COBRA PRODUCT OR AS
THE PARENT, OR LEGAL GUARDIAN OF THE OPERATOR, TO KEEP THISCOBRA
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.

3
Table Of Contents
General Information.........................................................................................................5
Specifications -General..............................................................................................5
Specifications -Torque Values ..................................................................................6
Optional Suspension Components............................................................................7
Break-In Procedure......................................................................................................8
Starting Procedure.......................................................................................................9
General Tips................................................................................................................10
Maintenance....................................................................................................................11
Schedule & Tips .........................................................................................................11
M1: Replacing Transmission Lubricant...................................................................11
M2: Chain adjustment................................................................................................12
M3: Air Filter Cleaning ...............................................................................................13
M4: Front end..............................................................................................................15
Toe in adjustment...................................................................................................15
Steering....................................................................................................................15
Parts.................................................................................................................................16
Parts –Air Inlet System.............................................................................................16
Parts –Bars and Steering.........................................................................................17
Parts –Bumper, Nerf & Grab Bars..........................................................................18
Parts –Carburetor......................................................................................................19
Parts –Clutch Actuation............................................................................................20
Parts –Coolant System.............................................................................................21
Parts –Electrical System..........................................................................................22
Parts –Engine Clutch................................................................................................23

4
Parts –Engine –Clutch / Kick Cover..................................................................24
Parts -Engine -Ignition Side................................................................................25
Parts -Engine –Kick Mechanism........................................................................26
Parts –Engine –Shift Mechanism ......................................................................27
Parts –Engine –Top End.....................................................................................28
Parts -Engine -Transmission..............................................................................29
Parts –Exhaust System............................................................................................30
Parts -Front A-Arms & Steering Upright................................................................31
Parts –Front Brakes..................................................................................................32
Parts –Front Shock...................................................................................................33
Parts –Miscellaneous ...............................................................................................34
Parts –Plastic Bodywork & Seat.............................................................................35
Parts –Rear Brake.....................................................................................................36
Parts –Rear Drive......................................................................................................37
Parts –Rear Shock....................................................................................................38
Parts –Swingarm Assembly.....................................................................................39
Parts –Tie Rod Assembly........................................................................................40
Engine Parts / Service...................................................................................................41
ES1: Fuel & Air System.............................................................................................41
Reeds.......................................................................................................................41
Carburetor Cleaning...............................................................................................42
ES2: Exhaust ..............................................................................................................43
Tuning ..............................................................................................................................43

5
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, reedvalve
Cooling system Liquid-cooled
Displacement 64.8 cc (3.95 Cubic inches)
Bore and stroke 43 mm x 44.6 mm
Ignition system Electronic
Spark plug Champion 8339
Gap 0.023” –0.025” (0.58–0.64 mm)
Fuel type 93 octane pump gasoline
OTHER RACE FUELS ARE NOT RECOMMENDED
Oil type Cobra Venom 2-cycle Race Oil
Fuel / oil mix ratios 32:1
Ignition timing .050” (1.3mm) BTDC
Carburetion 26mm Mikuni VM
Main jet 190
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 85W 90 Gear Lubricant
Quantity 530 ml (18 oz)

6
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 14 170 19 7mm
Engine oil drain 336 48 x 1.25
Engine oil fill 224 2.7 14 x 1.0
Spark Plug (SP) (SP) (SP) 14 x 1.25
Crank case half 560 6.8 6 x 1.0
Crank case cover 560 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.

7
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 21 250 28 14 x 2.0
Units of mm unless otherwise specified
(R)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) Helper Main
Less than 65 SCEX0110 (WHITE,
110 LB/IN)
SCEX1350 (RED, 350 LB/IN)
65 to 100 SCEX0125 (GOLD,
125 LB/IN) SCEX1375 (WHITE, 375 LB/IN)
Greater than 100 SCEX0150 (150 LB/IN) SCEX0400 (YELLOW, 400 LB/IN)

8
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 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 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 15minutes 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!

9
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.
•Verify that the chain rollers do not have improper wear.
•Inspect the frame, for;
oCracks in the metal.
oCracking paint which might indicate overly stressed material.
•Verify that the handlebars are tight.
•Check the throttle for;
oSmooth operation and sound closing.
oFrayed 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 tothe 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 inspectionis 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 throttleno 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.

10
General Tips
1. Always wear ahelmet and other protective riding gear.
2. Cobra recommends that you tell your child to take it easy the first coupleof
minutes in practice until the engine comes up to full operating
temperature.
3. Make sure your riders’ foot is not resting on therear 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. Keep steering stops adjusted so that the wheels do not scrape on the A-
arms
8. Mare sure that there is adequate free play in both thefront lever and rear
brake pedal.
9. The appearance of black ‘stuff’ in the coolant is likely due to a head seal
being compromised. Replace the head seals and keep an eye on the
coolant.
10. 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, ECXxxx5xxx is a 2005 MY ECX70.

11
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
oInspect the fuel filter for contaminates.
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.
oSpray all moving parts with WD40 or other light oil.
oCheck drive chain for
§Proper tension and adjust if necessary.
§Adequate lubrication and lubricate if necessary.
oCheck 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
oReplace the transmission oil.
•Every 10 hours of operation
oHave 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) 85W 90 gear 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).
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:

13
•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).
Figure 1
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 chainfree 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.
M3: Air Filter Cleaning
This Cobra Motorcycle comes with a unique air filter / air boot unit designed to
facilitate motorcycle service.

14
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 againwith 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.

15
M4: Front end
Toe in adjustment
Riders and parents have provided feedback that they prefer the toe in adjustment
between ½” (12mm) out to ½” (12mm) in. This is set by adjusting the length of
the tie rod assemblies. See figure 3 for direction of turn.
Adjust both wheels so that they have the same amount of toe in.
Figure 3
Steering
The unique Cobra front end will exhibit some free play from the factory and that
the seals (it that’s what you want to call them) will fall out after the first ride. We
have found that this causes no adverse effects and that the looseness does not
get significantly worse as long as the bearings are sprayed with a spray lubricant
(WD40 or similar) upon each ride.

16
Parts
Parts –Air Inlet System
Figure 4 Coolant System
REF # PART # DESCRIPTION
1RCDC0001 AIR FILTER ASSEMBLY
2MCKGHO03 HOSE CLAMP –FILTER TO CARB
3RCEX0003 CARBURETOR 26MM MIKUNI VM
4MCMUCL10 HOSE CLAMP –CARB TO INLET BOOT (WIDE)
5ECEX0012 INLET BOOT
6MCMUCL03 HOSE CLAMP –BOOT TO REED MANIFOLD (NARROW)
7ECDC0094 INLET MANIFOLD WITH REED ASSEMBLY
REEDS -REMPLACMENT STOCK
ECDCRD15 REEDS –SOFT
8HCBC0602 M6 X 20 SOCKET HEAD CAP SCREW (4 REQ’D)
9ECDC0093 GASKET –INLET (2 PLACES)
10 RCMU0001 SPACER –REED
11 FCEX0016 THROTTLE, QUAD THUMB STYLE
12 FCPW0004 THROTTLE CABLE END GROMMET
13 RCEX0001 CABLE -THROTTLE
14 FCMU0027 FUEL LINE 5 INCH
15 FCDC0093 FILTER, FUEL
16 RCEX0019 COVER, AIR FILTER

17
Parts –Bars and Steering
Figure 5
Bars and Steering
REF # PART # DESCRIPTION
1FAEX0020 STEERING STEM
2TCEX0009 HANDLEBAR -QUAD
3FCEX0011 STEERING STEM BLOCK (2 REQ’D)
4MCEXBR06 STEERING STEM BUSHING –SPLIT
NOT SHOWN HCBB0403 4MM X 8 BUTTON HEAD SCREW (2 REQ’D)
5TCMU0404 BAR MOUNT KIT, SHORT –REPLACEMENT (2 REQ’D)
NOT SHOWN TCMU0403 BAR MOUNT KIT, TALL –OPTIONAL (2 REQ’D)
6HCBC0806 SOCKET HEAD CAP SCREW M8 X 30 (4 REQ’D)
7HCBC1001 M10X45 SOCKET HEAD CAP SCREW (2 REQ’D)
8HCNL1001 M10 LOCK NUT (2 REQ’D)
9HCWF0801 8MM FLAT WASHER
10 HCBH0810 8MM X 65 HEX HEAD BOLT (2 REQ’D)
11 HCNL1001 10MM LOCK NUT
12 HCWF0010 10MM FLAT WASHER
13 MCEXBR04 STEM PIVOT BUSHING -LOWER
14 MCMU0001 CROSS BAR PAD
15 TCEX0013 GRIPS SET OF TWO
16 HCBH0601 6MM X 16 HEX HEAD BOLT (2 REQ’D)
17 HCNS0601 6MM NUT (2 REQ’D)

18
Parts –Bumper, Nerf & Grab Bars
Figure 6
BODY PROTECTION
REF # PART # DESCRIPTION
1FCEX0024 NERF BARS (LEFT & RIGHT)
NOT SHOWN HCBH0808 8MM X 30 HEX HEAD BOLT (FRONT MOUNT, 2 PLACES)
NOT SHOWN HCBH0809 8MM X 50 HEX HEAD BOLT (REAR MOUNT, 2 PLACES)
NOT SHOWN HCWF0801 8MM FLAT WASHER (2 REQ’D)
NOT SHOWN HCNL0801 8MM LOCKNUT (2 REQ’D)
2FAEX0099 FRONT BUMPER
3HCBB0802 M8 X 20 BUTTON HEAD BOLT (4 REQ’D)
4FCEX0003 GRAB BAR
5HCBC0820 M8 X 20 SOCKET HEAD CAP SCREW (4 REQ’D)

19
Parts –
Carburetor
Figure 7
Carburetor accessories
REF # PART # DESCRIPTION
RCEX0003 CARBURETOR, 26MM MIKUNI VM
CABLE, THROTTLE
1RCEX0017 JET NEEDLE (5F21) STANDARD
RCEX0018 JET NEEDLE (5F3)
2RCEX0004 RUBBER, THROTTLE CABLE ADJUSTER
3RCEX0005 ADJUSTER, THROTTLE CABLE
4RCEX0006 LOCK NUT, THROTTLE CABLE ADJUSTER
5RCEX0007 GASKET, CARBURETOR BOWL
6RCEX0008 PLUG WASHER, MAIN JET
7RCEX0009 SPRING, THROTTLE VALVE
8RCEX0010 E-CLIP, NEEDLE
9RCEX0011 NEEDLE VALVE, SEAT ASSEMBLY
10 RCEX0012 SCREW, FLOAT BOWL
11 RCEX0013 SCREW, AIR ADJUSTING
12 RCEX0014 SPRING, AIR ADJUSTING SCREW
13 RCEX0015 SCREW, IDLE ADJUSTING
14 RCEX0016 SPRING, IDLE ADJUSTING SCREW
15 RCMU0xxx MAIN JET, xxx DENOTES SIZE (170, 175, 180, 185, 190, 195, 200, 205, 210)
16 RCEX00xx PILOT JET, xx DENOTES SIZE