Cobra PW3 2003 Application guide

2003 PW3
Owners / Service Manual
“CHAMPIONS START HERE”

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 MCPW2003.4

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 PW3 IS A COMPETITION MODEL ONLY AND IS NOT
MANUFACTURED FOR, NOR SHOULD IT BE USEDON 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 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 aperson 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.

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Table Of Contents
General Information.........................................................................................................4
Specifications -General..............................................................................................4
Specifications -Torque Values ..................................................................................5
Optional Components..................................................................................................6
Break-In Procedure......................................................................................................7
Starting Procedure.......................................................................................................8
General Tips..................................................................................................................9
Maintenance....................................................................................................................10
Schedule & Tips .........................................................................................................10
M1: Replacing Transmission / Clutch Lubricant....................................................11
M2: Chain adjustment................................................................................................12
M3: Front brake adjustment......................................................................................13
M4: Rear brake adjustment ......................................................................................14
M5: Air Filter Cleaning ...............................................................................................14
M6: Fork Oil Replacement........................................................................................15
M7: Clutch Adjustment ..............................................................................................16
Engine Service / Parts...................................................................................................17
ES1: Top End Parts ...................................................................................................18
ES2: Bottom end & transmission.............................................................................19
ES3: Clutch.................................................................................................................22
ES4: Ignition................................................................................................................23
ES5: Cooling System.................................................................................................24
ES6: Fuel & Air System.............................................................................................25
ES7: Exhaust ..............................................................................................................30
Chassis Service / Parts .................................................................................................30
CS1: Wheels & Tires .................................................................................................30
CS2: Suspension........................................................................................................32
Troubleshooting..............................................................................................................36

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General Information
Specifications -General
Items PW3
Dimensions
Wheelbase 35.75” (908mm)
Wheel size 10” (254mm)
Seat height 22” (559 mm) Stock #TCHO0001
23.9” (607 mm) Optional #TCHJ0001
Engine
Type 2-stroke, single cylinder, reed valve
Cooling system Liquid-cooled
Displacement 49.8 cc
Bore and stroke 39 mm x 41.7 mm
Ignition system Digital Electronic
Spark plug ChampionC53, NGK B11EGV
Gap 0.023” –0.025” (0.58–0.64 mm)
Fuel type Sunoco MO2X or 93 octane pump gasoline
OTHER RACE FUELS ARE NOT RECOMMENDED
Injector oil type Cobra Venom 2-cycle Race Oil
Fuel / oil mix ratios Fill oil reservoir as required
Ignition timing Fixed
Carburetion 12 mm Dell’Orto PHVA-PS
Main jet 82
Slow (Pilot) jet 42
Float height 5 mm +0.3mm (0.2” +0.012”)
Transmission
Speed Single
Clutch 3 shoe centrifugal
Final drive ratio 10/46 T
Transmission / clutch oil type Cobra Venom 3 Shoe Clutch Milk, or Dexron III
Quantity 250 ml (8.5oz)

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Chassis
Front tire 2.50 -10
Pressure 15 psi minimum
Rear tire 2.75 -10
Pressure 15 psi min. (20 psi for hard pack or rocky conditions)
Front fork Marzocchi 32mm
Fork oil type SAE 20 weight
Fork oil amount 200 ml (6.8 oz) oil change, 220 ml (7.4 oz) rebuild
Fork oil height 70 mm (2.75”) collapsed from top with spring (no
spacer)
Specifications -Torque Values
Torque ValueFastener
ft-lb in-lb Nm
Size &
Remarks
Front engine mount bolts 22 264 30 8 x 1.25
Rear engine mount bolts 22 264 30 8 x 1.25
Swingarm pivot bolt 21 250 28 14 x 2
Rear sprocket bolts 18 216 24 7 x 1
Rear axle bolts 25 300 34 12 x 1.25
Rear shock mounts 40 480 54 10 x 1.5
Clutch adjust access plug 10 124 14 12 x 1.25
Units of mm unless otherwise specified

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Optional Components
•Carburetor jets
oMain jets #’s 74, 76, 78, 80, 84, 86, 88
oSlow jets #’s 38, 40, 45,
•Sprockets
oFront sprocket, 11T
oRear sprocket, 39 T –45 T
•Seat –higher seat height 23.9” (607 mm) part # TCHJ0001
•Suspension Springs
Weight of Rider (lb) Fork Spring Shock Spring
Less than 38 (light) KCMZ0012A SCMU0321 (yellow, 320 lb/in)
38 –45 (std) KCMZ0012 SCMU1360 (red, 260 lb/in)
46 to 55 (stiff) KCMZ0012B SCMU1380 (white, 380 lb/in)
Extra stiff SCMU1400 (silver, 400 lb/in)
•Suspension Valving
Damping Rate Fork Valving
Compression
(right)
Fork Valving
Rebound
(left)
Shock Valving
(kit)
Soft (fast) KCMZ0033A KCMZ0032A SCMU0318A
Standard KCMZ0033 KCMZ0032 SCMU0318
Hard (slow) KCMZ0033B KCMZ0032B SCMU0318B

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Break-In Procedure
Your Cobra PW3 is a close-tolerance high performance machine and break-in
time is very important for maximum life and performance. The PW3 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!
Fill the fuel tank with 93 octane pump gas, or Sunoco MO2X without oil. Also, fill
the oil injection reservoir 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 ½ hour of operation
oFollow the starting procedure listed in this manual.
oAvoid 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.
•After 8 hours of operation
oChange the fork oil.
oHave a Certified Cobra Mechanic change the shock oil.
•Your bike is now ready for the highest level of competition!

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Starting Procedure
Before starting the machine inspect the following:
•Fill the 2-stroke injector oil reservoir with Cobra’s specially formulatedCobra
Venom 2-cycle Race Oil.
•Insure that the fuel tank contains an adequate volume of fuel to complete
the distance required. (Sunoco MO2X or 93 octane pump gas).
•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 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.
When your pre-ride inspection is complete the bike may be started. For a cold
engine follow this procedure.
1. Place the motorcycle on a stand of sufficient strength that positions the
motorcycle in a level upright position with the rear wheel off the ground.
2. On the carburetor, flip the black choke knob upward from the right side of
the bike.
3. Kick start the engine by kicking the lever forward.
4. Rev the engine in short spurts, turning the throttle no more than 1/4 open
until the engine will run without the choke.
5. Verify a functional engine shut-off switch by shutting off the engine.
6. 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 foot brake 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
bottom edge of the seat, or water is apt to enter the airbox.
7. Your Cobra Motorcycle has a 10 digit VIN (Vehicle Identification Number).
The first two digits indicate the model and the seventh indicates the model
year (MY).
a. Example, OIxxxx3xxx is a 2003 MY PW3.