Cobra Electronics King 2003 User Manual
2003 KING
Owners / Service Manual
“CHAMPIONS START HERE”
For parts orders contact your local dealer
To locate your closest Cobra dealer
log on to
www.cobramotorcycle.com
or call
(330) 549-9600
If you need technical assistance
contact your local dealer or call
the Cobra Technical Support Hotline at
(330) 549-9603
Cobra Motorcycle MFG., Inc.
11511 Springfield Road
North Lima, Ohio 44452
1
MCKG2003.3
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 KING 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
Optional Components..................................................................................................5
Specifications - Torque Values ..................................................................................6
Break-In Procedure......................................................................................................7
Starting Procedure.......................................................................................................8
General Tips ..................................................................................................................9
Maintenance......................................................................................................................9
Schedule & Tips ...........................................................................................................9
M1: Replacing Transmission / Clutch Lubricant....................................................10
M2: Chain adjustment................................................................................................12
M3: Rear brake adjustment ......................................................................................12
M4: Air Filter Cleaning ...............................................................................................13
M5: Fork Oil Replacement........................................................................................13
Engine Service / Parts...................................................................................................15
ES1: Engine Service..................................................................................................17
E1: Engine Removal..............................................................................................18
E2: Complete Engine Disassembly Procedure .................................................19
E3: Top End Disassembly Procedure.................................................................19
E4: Splitting the Cases..........................................................................................20
E5: Engine assembly.............................................................................................21
ES3: Clutch.................................................................................................................26
ES4: Ignition................................................................................................................30
ES5: Cooling System.................................................................................................32
ES6: Fuel & Air System.............................................................................................36
ES7: Exhaust ..............................................................................................................39
Chassis Service / Parts .................................................................................................40
CS1: Wheels & Tires .................................................................................................40
CS2: Suspension ........................................................................................................47
Troubleshooting..............................................................................................................50
3
General Information
Specifications - General
Items KING
Dimensions
Wheelbase 39” (991mm)
Wheel size 10” (254mm) rear, 12” (305mm) front
Seat height 26” (660mm)
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 Electronic
Spark plug Splitfire SF406B
Gap 0.023” – 0.025” (0.58 – 0.64 mm)
Ignition timing 0.050” (1.3 mm) Before To Dead Center (BTDC)
Fuel type Sunoco MO2X or 93 octane pump gasoline
Oil type Cobra Venom 2-cycle Race Oil
Fuel / oil mix ratios Between 32:1 and 40:1 (after engine Break-In is
Carburetion 19 mm Dell’Orto
OTHER RACE FUELS ARE NOT RECOMMENDED
complete)
Main Jet 94
Slow (Pilot) jet 65
Float Height 16mm + 0.5mm (0.63” + 0.020”
Transmission
Speed Single
Clutch Cobra 3 shoe
Final drive ratio 13/39 T
Chain 100 links 420
Transmission / clutch oil type Cobra Venom 3 Shoe Clutch Milk, or Dexron III
Quantity 235 ml (8.0oz)
4
Chassis
Front tire 2.50 - 12
Pressure 15 psi minimum
Rear tire 2.75 - 10
Pressure 15 psi min. (20 psi for hard pack or rocky conditions)
Front fork Cobra 30mm USD
Fork oil type SAE 5 weight
Fork oil amount 118 ml (4.0 oz)
Optional Components
• Carburetor jets
• Sprockets
o Front
o Rear
• Suspension Springs
Weight of Rider (lb) Fork Spring Shock Spring
Less than 51 7 lb/in,
KCKG0007
51 - 60 9 lb/in,
KCKG0009
Greater than 60 12 lb/in,
KCKG1200
• Suspension Valving
Damping Rate Fork Valving
Compression
(base valve)
Soft (fast) KAKG0013 KAKG0016 SCKGOH24A
Standard KAKG0014 KAKG0017 SCKGOH24
Hard (slow) KAKG0015 KAKG0018 SCKGOH24B
• Cobra BIG AIR SX Fork Kit part #KKKG2003
SCKGOH10 (yellow, 175lb/in)
SCKGOH85 (gray, 185 lb/in)
SCKG0H, (white, 195 lb/in)
Fork Valving
Rebound
(mid valve)
Shock Valving
(kit)
5
Specifications - Torque Values
Torque Value
Size &
Fastener ft-lb in-lb Nm
Cylinder head nuts 9.2 110 12 ¼”
Crankcase bolts 6.6 80 9 6 x 1.0
Spark plug (SP) (SP) (SP) 14 x 1.25
Stator bolts 2.1 25 2.8 #8
Stator cover bolts 1.7 20 2.3 #8
Clutch cover bolts 5.8 70 7.9 6 mm
Clutch 40 480 54 10***
Front axle nut 25 300 34 12 x 1.25
Front brake caliper
Engine mount bolts 22 265 30 8 mm
Swingarm Pivot 21 250 28 14 mm
Intake manifold bolts 4.6 55 6.2 6 mm
Rear Axle Bolt 25 300 34 12 mm
Remarks
Rear Sprocket Bolts 18 216 24 7 mm
Fork cartridge rod 12 144 16
Triple clamp bolts 6 72 8 6 x 1.0
Fork cap 5 60 6.7 1.25” x 18
Ignition rotor nut 40 480 54 10 mm**
** Use green (wicking / bearing retainer) thread locker, with primer, on the
flywheel / crankshaft taper but none on the threads.
*** Use green (wicking / bearing retainer) thread locker, with primer, on the
crankshaft / clutch taper but use red (high strength) thread locker, with primer, on
the nut.
(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
Break-In Procedure
Your Cobra KING is a close-tolerance high performance machine and break-in
time is very important for maximum life and performance. The KING 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, oil, or fuel/oil mixture 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!
NOTE:
During break-in the bike will likely loose some engine coolant through the radiator
overflow hose. Loosing up to 4 oz (120 ml, ½ cup) is normal. Proper coolant level
will cover the top of the radiator cores. Removing the radiator cap and looking
inside is the only way to check the coolant level.
Never open the radiator cap of a machine that has a hot or warm engine or one
that has recently been ridden. Burning and scalding could occur.
CAUTION:
It is important that the radiator cap is installed correctly and completely otherwise
engine damage could occur.
7
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 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.
• Insure that the fuel tank contains an adequate volume of fuel / oil mixture to
complete the distance required. (Sunoco MO2X or 93 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.
When you r 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. Pull up the choke knob and turn it to lock it.
3. Kick start the engine.
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.
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. 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, ACxxxx3xxx is a 2003 MY King.
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 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 Inspect the rear sprocket damper plate for bending or warping.
Straighten or replace if more than 1/16” (1.6 mm) from flat.
• 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.
9
CAUTION:
1. Because of the amount of heat generated by the clutch and engine during
extended periods of riding, it is advisable to remove the ignition cover
afterward to allow the ignition to cool off. The heat transfers through the
cases and can damage the stator as it cools off because of lack of airflow
around the stator.
2. 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.
3. 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.
4. If your kick-starter lever does not return to the rubber bumper, use WD-40
or light penetrating oil under the plastic cover behind the spring on the
shaft. The shaft is a very close fit to the case and also has an O ring in it
and is difficult to get lubrication to which may cause binding. If it does not
loosen up, remove the kick-starter cover and kicking assembly. Grease the
shaft.
M1: Replacing Transmission / Clutch
Lubricant
Tools needed:
• 225 ml (7.6 oz) Cobra Venom 3 Shoe Clutch Milk (Part # MCMUGF01), or
Dexron III Automatic Transmission Fluid.
• 13 mm combination wrench
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.
10
2. Lean bike against something or set on stand with oil drain hole.
3. Using a 13 mm wrench, remove the oil drain bolt located on the right side of
the engine, on the clutch cover, near the brake lever (Item 2, figure 1).
Figure 1
NOTE: You may need to adjust the brake pedal (up or dow n) to gain access to
the drain bolt.
4. After it has drained, reinstall the bolt being sure that the copper gasket is in
place. Torque to 15 Nm (11 ft-lb).
5. Reapply oil from oil fill plug 235 cc Cobra Venom 3 Shoe Clutch Milk, or
Dexron III Automatic Transmission Fluid, thru the fill plug.
NOTE lean bike over onto it’s left hand side so that the clutch cover is up unless
you have a squeeze bottle.
6. Reapply the oil fill bolt, hand tight, being sure the fiber gasket is in place.
CAUTION:
Cobra has spent considerable time and money developing the proper lubrication
to handle the harsh environment of the automatic clutch and transmission of this
motorcycle. Cobra was forced to put forth this effort because the other available
options and not adequate. Cobra’s specially developed Cobra Venom 3 Shoe
Clutch Milk (Part # MCMUGF01) is the recommended lubricant for your KING
motorcycle.
11
M2: Chain adjustment
Figure 2
M3: Rear brake adjustment
Tools recommended for rear brake maintenance:
10mm open end wrench
There are 2 adjustments on the brake.
1. Make sure that the rear
wheel is aligned properly.
2. Push down on the seat,
compressing the suspension down to where the
chain is tightest.
3. The chain should not be
too tight but not too
loose. A minimum of 2.5
in. of slack should be
between the swing arm
and the chain.
Figure 3, adjust brake lever free height Figure 4, adjust brake lever ‘free play’
From the brake lever:
1. Loosen the 10mm nut on the back of the brake pedal.
2. Adjust the bolt to desirable position
3. Tighten the 10mm nut.
From the brake hub:
1. Adjust the wing nut up to desirable position.
CAUTION:
If you tighten the wing nut up too much, the brakes may hang up. If so, the brake
pads will burn up, and need replaced.
12
M4: Air Filter Cleaning
Tools recommended for air filter maintenance:
• Flat head screwdriver
• Air filter oil
• 5mm hex key
• Foam filter oil
The Cobra is equipped with a special designed sock filter. It is very important to
keep it 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.
Make sure you change your filter after each moto. We recommend carrying 3 or
more filters in your toolbox.
1 for practice
1 for the each moto
In our testing when filters are properly oiled, no water, dirt or mud can penetrate
through the yellow or red foam to the carburetor inlet. It is important that the filter
does not touch any of the frame components in a rainy, muddy situation. We
offer two different filters. One filter for the use in sand (part # RCMU0101), and
the regular filter for regular use (part # RCMU0206).
When washing your bike cover the carburetor/filter with a suitable shield capable
of keeping water from entering the engine. Cobra has a rubber clamp-on plug for
the carburetor referred to as a carburetor condom (part # RCMU0104).
M5: Fork Oil Replacement
Tools required
• Two 19 mm wrenches or sockets
• 4 & 5 mm hex key (Allen wrench)
• 1 1/8” wrench or socket
• 5 wt fork oil
Disassembly procedure
1. Remove the front wheel (19 mm wrench).
2. Remove the brake caliber from the fork leg (4 mm hex key).
3. Loosen the fork caps (1 1/8” socket).
4. Remove the fork legs from the triple clamps (5 mm hex key).
5. One leg at a time
a. Remove the fork cap from the leg.
b. Separate the fork cap from the damper rod.
c. Pull out the fork spring.
d. Place upside down over a suitable pan , tray, or container.
13
e. Work the damper rod up and down several times.
f. Allow to drain completely.
Assembly procedure
1. Fill the fork leg with 4 oz (118 ml) 5 wt fork oil.
2. Measure the fork oil level to the top of the fork tube with the leg collapsed,
and record for tuning purposes.
3. Install the fork spring.
4. Reconnect the damper rod to the fork cap (12 ft-lb, 16 Nm).
CAUTION:
The damper rod is hollow and will break if the nut is over tightened.
5. Reinstall the for cap into the fork leg (5 ft-lb, 6.7 Nm)
6. Reinstall the fork legs into the clamps (6 ft-lb, 8 Nm).
7. Reinstall the brake caliper.
8. Reinstall the front wheel (25 ft-lb, 34 Nm).
14
Engine Service / Parts
REF. #
PART #
DESCRIPTION
REF. #
PART #
DESCRIPTION
1
CAKG0002
Clutch, Complete
44
ZCKG0002
Gasket, Base
2
CAKG0004
Shoes, Clutch w/ Washer Springs
45
ECKG0041
Cylinder, 50cc
3
CAMU0008
Spring Set, Washer type for Clutch
46
ZCMUOR07
Oring, Exhaust Flange
4
CCMU0031
Arbor for 3 Shoe Clutch
47
ECKG0015
Exhaust Flange
5
ECMU0018
Nut, Crankshaft Starter
48
HCBC0602
Screw, 6x20
6
ECMU0033
Clutch Hub w/ Gear
49
ECMU0008
Stud, Cylinder
7
ECMU0040
Clutch to hub spacer
50
ZCMUOR03
Oring, Cylinder head, Small
8
ECDC0105
90 Degree Crankcase Vent
51
ZCMUOR05
Oring, Cylinder head, Medium
9
ECMU0017
Seal, Crankshaft
52
ECKG0121
Cylinder Head Dome-Insert
10
ECMU0016
Bearing, Crankshaft
53
ECMU0403
Spring, Kickstarter Return
11
ECMU0001
Bearing, Trans., Secondary Gear
54
HCNS1401
Nut, 1/4-20
12
ECMU0020
Bearing, Trans., Precision
55
ZCMUOR02
Oring, Cylinder head, Large
13
ECMU0105
Gear, Trans., Primary
56
ZCMUOR08
Oring, Cylinder head
14
HCNS1202
Nut, 1/2-20, Left Hand
56A
ZAKGOR02
Oring Kit, Top End
15
ECKG0018
Crankcase, Clutch side
57
ECKG0025
Cylinder Head - Outer Cap
16
ECMU0131
Water Elbow
58
HCWF1401
Washer, 1/4"
17
HCBH0805
Screw, M8x12mm
59
ICMU0006
Rotor
18
ECMU0103
Shaft, Trans., Secondary w/gear
60
ICMU0007
Stator
19
ECMU0104
Shaft, Trans., Output w/gear
60A
MCKGGR00
Grommet, Engine case
20
ECKGBR01
Bearing, Trans., Output shaft
61
ECKG0073
Impeller, Waterpump
21
ZCKG2001
Gasket, Crankcase
62
ECKG0074
Seal, Waterpump
22
HCDP1401
Dowel, for Engine Cases
63
ECKG0203
Intake Manifold
23
ECMU0038
Crankshaft, Welded and Balanced
64
ZCMU0032
Gasket, Reed to case
24
ECKG0017
Crankcase, Ignition side
65
ZCMU0031
Gasket, Intake to Reed
25
ECKG0004
Snap Ring, Int. for Water Pump
66
ECKG0202
Reed Assembly
26
ECKGSE01
Seal, Output shaft
66A
ECKG0204
Reed Kit
27
HCBC0606
Screw, M6x45
67
ZCKG0101
Gasket, Ignition Cover
28
HCBC0604
Screw, M6x35
68
ECKG0001
Cover, Ignition
28A
HCBC0603
Screw, M6x30
69
HCBC0802
Screw, 8-32x1-3/4
29
HCBC0608
Screw, M6x55
70
ECMU0043
Piston Kit
30
PCKG0013
Sprocket, 13T for output shaft
70A
ECMU0055
Piston Ring
30A
ECKGSR03
Snap Ring, Ext., for output shaft
71
ECKG0012
Wrist pin
31
HCWP0001
Washer, Stator
72
ECMU0077
Bearing, Wrist Pin
32
HCBH0803
Screw, 8-32x7/8
73
ECMUSR00
Snap Ring for Piston
33
HCBC0801
Screw, 8-32x1-1/2
74
ECMUSP01
Spring, Kick Start Dog
34
HCNS1001
Nut, 10mm
75
ECMU0207
Gear, Kickstarter, Small
35
ECKG0042
Pulley, Waterpump-Crank
76
ZCMU0030
Gasket, Clutch Cover
36
ECKG0070
Belt, Waterpump
77
ECMU0205
Kick Starter Rubber
37
HCBB0001
Screw, 10-32x1/2"
78
HCWC0000
Gasket, Copper
37A
HCBC1033
Screw, 10-32x3/4"
79
HCBH0805
Screw, M8x12mm
38
HCWL0001
Washer
80
ECMU0204
Kick Starter Dust Shield
39
ECMU0080
Belt Retainer
81
ZCMU0001
Gasket, Oil fill plug
40
ECKG0075
Pulley, Waterpump-Fan
82
ECMU0037
Oil fill plug
41
HCSS8201
Screw, 8-32x3/8
83
ECMU0202
Kickstarter Lever
42
ECKG0072
Bearing, Waterpump
84
ECMU0027
Kickstarter, complete
43
ECKG0141
Shaft, Waterpump
85
ECMU0003
Brass Clutch Bushing
2003 KING ENGINE ASSEMBLY REFERENCE DRAWING
15
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