Cobra PW3 2003, 2003 CH2 Owner's Service Manual

2003 PW3

Owners / Service Manual

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1

Cobra Motorcycle MFG., Inc.

11511 Springfield Road
North Lima, Ohio 44452

MCPW2003.4

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 USED ON 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 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.

2

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: Igni tion................................................................................................................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

3

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 Champion C53, NGK B11EGV

Gap 0.023” – 0.025” (0.58 – 0.64 mm)

Fuel type Sunoco MO2X or 93 octane pump gasoline

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

OTHER RACE FUELS ARE NOT RECOMMENDED

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

4

Quantity 250 ml (8.5oz)

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 Value Fastener

Size &

ft-lb in-lb Nm

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

Remarks

5

Optional Components

• Carburetor jets

o Main jets #’s 74, 76, 78, 80, 84, 86, 88
o Slow jets #’s 38, 40, 45,

• Sprockets

o Front sprocket, 11T
o Rear 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

Soft (fast) KCMZ0033A KCMZ0032A SCMU0318A

Standard KCMZ0033 KCMZ0032 SCMU0318

Hard (slow) KCMZ0033B KCMZ0032B SCMU0318B

Compression

(right)

Fork Valving

Rebound

(left)

Shock Valving

(kit)

6

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

o Follow the starting procedure listed in this manual.
o 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.

• After 8 hours of operation

o Change the fork oil.
o Have a Certified Cobra Mechanic change the shock oil.

• Your bike is now ready for the highest level of competition!

7

Starting Procedure

Before starting the machine inspect the following:

• Fill the 2-stroke injector oil reservoir with Cobra’s specially formulated Cobra
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;

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 posit ion 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 you r 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.

8

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.

9

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 Fill the 2-stroke injector oil reservoir.
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 Insure that the ignition stator and rotor are clean and dry.
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.

o Fill the 2-stroke injector oil reservoir with Cobra’s specially formulated

Cobra Venom 2-cycle Race Oil.

• Every 2 hours of operation
o Replace the transmission oil.

• Every 10 hours of operation

o Replace the fork oil.
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.

10

Be sure the fuel tank and carburetor have been removed and safely located
away from the welding process.

2. The frame is 4130 Chrome Moly 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 / Clutch
Lubricant

Tools needed:

• 250 ml (8.5oz) Cobra Venom 3 Shoe Clutch Milk (Part # MCMUGF01) or

Dexron III Automatic Transmission Fluid

• #3 Phillips screwdriver

• large flat blade screwdriver or coin

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 somethin g or set on stand with oil drain hole.

3. Using Phillips screwdriver, remove the oil drain bolt located on the right side

of the engine (figure 1).

Figure 1

11