Cobra 2006 King 50 User manual

2006 King 50
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 MCKG2006.2

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 KING IS A COMPETITION MODEL ONLY AND IS NOT
MANUFACTURED FOR, NOR SHOULD IT BEUSED 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 THAN 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.

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Table Of Contents
GENERAL INFORMATION............................................................................................5
SPECIFICATIONS -GENERAL...........................................................................................5
OPTIONAL COMPONENTS................................................................................................6
SPECIFICATIONS -TORQUE VALUES ..............................................................................7
BREAK-IN PROCEDURE...................................................................................................8
STARTING PROCEDURE ..................................................................................................9
GENERAL TIPS..............................................................................................................10
MAINTENANCE .............................................................................................................10
SCHEDULE & TIPS.........................................................................................................10
REPLACING TRANSMISSION / CLUTCH LUBRICANT ......................................................12
CHAIN ADJUSTMENT......................................................................................................13
REAR BRAKE MAINTENANCE ........................................................................................13
AIR FILTER CLEANING...................................................................................................15
FORK OIL REPLACEMENT.............................................................................................17
PARTS .............................................................................................................................19
PARTS –AIRBOX & INLET SYSTEM..............................................................................19
PARTS –BARS AND CONTROLS ...................................................................................20
PARTS -CARBURETOR .................................................................................................21
PARTS –COOLANT SYSTEM.........................................................................................22
PARTS –ELECTRICAL SYSTEM.....................................................................................23
PARTS –ENGINE –BOTTOM END AND TRANSMISSION...............................................24
Parts –Engine Clutch and Kicker........................................................................25
Parts –Engine –Ignition and Water Pump........................................................26
Parts –Engine –Top End.....................................................................................27
PARTS –EXHAUST SYSTEM .........................................................................................28
PARTS –FORKS & TRIPLE CLAMPS.............................................................................29
PARTS –FORKS –LEG ASSEMBLY ..............................................................................30
PARTS –FRAME I..........................................................................................................31
Parts –Frame II......................................................................................................32
PARTS –FRONT BRAKES..............................................................................................33

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PARTS –FRONT WHEEL...............................................................................................34
PARTS –PLASTIC BODYWORK & SEAT........................................................................35
PARTS –REAR BRAKE..................................................................................................36
PARTS –REAR WHEEL.................................................................................................37
PARTS –SHOCK ...........................................................................................................38
PARTS –SWINGARM ASSEMBLY ..................................................................................39
PARTS –SWINGARM ASSEMBLY ..................................................................................39
SERVICE.........................................................................................................................40
ENGINE SERVICE...........................................................................................................40
Engine Removal.....................................................................................................41
Complete Engine Disassembly Procedure.........................................................42
Top End Disassembly Procedure........................................................................42
Splitting the Cases.................................................................................................43
Engine assembly....................................................................................................44
CLUTCH .........................................................................................................................46
IGNITION ........................................................................................................................51
COOLING SYSTEM.........................................................................................................53
FUEL & AIR SYSTEM.....................................................................................................57
EXHAUST.......................................................................................................................60
WHEELS & TIRES..........................................................................................................61
BRAKES.........................................................................................................................61
FRONT FORKS...............................................................................................................62
REAR SHOCK.................................................................................................................64
TUNING ...........................................................................................................................65
GEARING .......................................................................................................................65
SUSPENSION.................................................................................................................67
CARBURETION...............................................................................................................68
TROUBLESHOOTING ..................................................................................................71
INDEX..............................................................................................................................72

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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
Coolant Liquid Performance Mini Coolant or Antifreeze
Displacement 49.8 cc
Bore and stroke 39 mm x 41.7 mm, “V” head
Ignition system Electronic, analog advance
Spark plug Champion 8339-1, 8332-1 hotter, 8904-1 colder
Gap 0.023” –0.025” (0.58–0.64 mm)
Ignition timing 0.040” (1.02 mm) Before To Dead Center (BTDC)
Fuel type High octane pump gasoline
RACE FUELS ARE NOT RECOMMENDED
Oil type Cobra Venom 2-cycle Race Oil
Fuel / oil mix ratios Between 32:1 and 40:1 (after engine Break-In)
Carburetion 19 mm Dell’Orto
Main Jet 96
Slow (Pilot) jet 65
Float Height 16mm +0.5mm (0.63” +0.020”)
Transmission
Speed Single
Final drive ratio 14/38 T
Chain 100 links 420
Transmission / clutch oil type Cobra Venom 3 Shoe Clutch Milk
Quantity 235 ml (8.0oz)

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Chassis
Front tire 2.50 -12
Pressure 16 psi minimum
Rear tire 2.75 -10
Pressure 16 psi min. (20 psi for hard pack or rocky conditions)
Front fork Cobra 30mm USD
Fork oil type SAE 7 weight
Fork oil amount 107 ml (3.6oz)
Optional Components
Call your dealer, or the factory, for details
•Carburetor jets
•Flat clutch washers (see clutch service section)
•Pre filter for the airbox
•Sprockets
oFront
oRear
•Suspension Springs
Weight of Rider (lb) Fork Spring Shock Spring
Less than 51 0.23 kg/mm
KCKG1223 gray, 3.5 kg/mm SCKGFX35
51 -60 0.25 kg/mm
KCKG1206 yellow, 3.7 kg/mm SCKGFX95
Greater than 60 0.27 kg/mm
KCKG1227 gold, 3.9 kg/mm SCKGFX39
•Suspension Valving
Damping Rate Fork Valving
Compression
(base valve)
Fork Valving
Rebound
(mid valve)
Shock Valving
(kit)
Soft (fast) KAKG0023 KAKG0026 SKKGFX02
Standard KAKG0022 KAKG0025 SKKGFX01
Hard (slow) KAKG0024 KAKG0027 SKKGFX03
•Tires
•Tubes or ‘Tire Balls’

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Specifications -Torque Values
Torque Value
Fastener ft-lb in-lb Nm Size & Remarks
Cylinder head
nuts 8.8 105 12 M6 x 1.0
Crankcase
bolts 8.8 105 12 M6 x 1.0
Spark plug (SP) (SP) (SP) M14 x 1.25
Stator bolts 2.1 25 2.8 M5 X 0.8
Stator cover
bolts 1.7 20 2.3 M4 X 0.75
Clutch cover
bolts 5.8 70 7.9 M6 X 1.0
Clutch nut 35 420 47 M10 x 1.25*
Clutch bolts 12 144 16 M6 x 1.0
CFD nut 55 664 75 ½” x 20 LHT
Front axle nut 25 300 34 M12 x 1.25
Engine mount
bolts 22 265 30 M8 X 1.25
Swingarm
Pivot 21 250 28 M14 X 2.0
Intake manifold
bolts 4.6 55 6.2 M6 X 1.0
Rear Axle Bolt 25 300 34 M12 X 1.25
Rear Sprocket
Bolts 18 216 24 7 mm
Fork cartridge
rod 12 144 16
Triple clamp
bolts 672 8M6 x 1.0
Fork cap 560 6.7 1.25” x 18
Ignition rotor
nut 40 480 54 M10 x 1.25*
* Apply high strength thread locking agent when installing
(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.

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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
high-octane pump gas, 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.
•Start bike on stand
•First 5 minute period, operate the bike on the stand with a combination of idle
and high RPM operation. (avoid prolonged high RPM but spin the rear
wheel good at least once or twice per minute)
•Allow bike to cool
•Ride for 15 minutes maximum (avoid prolonged high RPM operation and
avoid abusing the clutch with throttle blipping.
•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.
•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!
NOTE:
During break-in the bike will likely lose some engine coolant through the radiator
overflow hose. Losing 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.

9
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.
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 and sliders do not have improper wear.
•Verify that the handlebars are tight.
•Check the throttle for smooth operation and sound closing.
•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. (High 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 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. 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. Also, for
best clutch performance, warm up the bike before taking off.

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This is a high performance race motorcycle. Too much application of throttle will
likely land your little racer on his or her arse. Fenders can be replaced but
bruised egos and other body parts take longer.
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. Filling your transmission with more than 8.0 oz (235ml) of lubricant may
help to transfer heat from the clutch, but be aware that this extra oil will
increase the frictional drag on the engine, thus reducing power, and will
often get purged out the crankcase vent during riding.
7. New chains will stretch on first use. Never install a new chain prior to a
race. Always ‘break’ them in during practice.
8. 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, Acxxxx6xxx is a 2006 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.
•Betweeneach ride
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.
oInsure that the ignition stator and rotor are clean and dry.

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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.
oCheck the rims for signs of stress, like cracks around the rim, spokes
and hub.
•Every 2 hours of operation
oReplace the transmission oil.
•Every 10 hours of operation
oReplace the fork oil.
oHave the shock oil replaced by a Certified Cobra Mechanic.
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.
3. Inspect CFD every couple months and replace paper when thickness is less
than 0.6mm.
Be sure the fuel tank and carburetor have been removed and safely located
away from the welding process.
4. 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.
5. If your kick-starter lever does not return properly, first try loosening the six
kick/clutch cover screws ½ turn. Hold the kick lever ½ way down while
retightening the six screws starting for the center and working out.

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Replacing Transmission / Clutch Lubricant
Tools needed:
•235 ml (8.0 oz) Cobra Venom 3 Shoe Clutch Milk (Part # MCMUGF01).
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 is ‘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. Remove the oil drain plug located on the right side of the engine, on the
clutch cover, near the brake lever (figure 1).
Figure 1
4. After it has drained, reinstall the plug, being sure that the gasket is in place.
5. Reapply oil from oil fill plug 235 cc (8.0 oz) Cobra Venom 3 Shoe Clutch Milk
thru the oil 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 plug, 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

13
motorcycle. Cobra’s specially developed Cobra Venom 3 Shoe Clutch Milk (Part
# MCMUGF01) was formulated to provide superior lubrication and cooling
capability over extended periods of time and is the recommended lubricant for
your Cobra motorcycle.
Chain adjustment
Figure 2
1. Make sure that the rear
wheel is aligned properly.
2. Push down on the seat,
compressing the suspen-
sion down to where the
chain is tightest. At this
point, there should be a
minimum of 1” of slack.
3. With the rear wheel
elevated, there should be
a minimum of 2.5” of
slack between the swing
arm and the chain.
Rear Brake Maintenance
CAUTION:
Too little brake pedal free-play will allow the brake pads to drag causing the pads
to wear prematurely and possible engine component failures. Too muchfree-play
will not allow the rider to apply the brakes quickly.
1. Set pedal height/position first, then
2. Set pedal free play.
Brake pedal height can be adjusted with the bolt and nut located under the rear
of the brake pedal. The free-play is adjusted with the adjustable plunger on the
end of the brake pedal.
CAUTION:
Use only DOT 4 brake fluid
Setting rear brake pedal position (see figure 2b):
1. Loosen the lock nut (10mm wrench).
2. Adjust the brake lever stop (10mm wrench) so that the lever is comfortably
reachable in both:
a. Standing riding position, and
b. Sitting riding position.
3. Tighten the lock nut (10 mm wrench).

14
Figure 2b
CAUTION:
Adequate pedal free play is required so that the brake pads do not drag on the
rotor. 1” MINIMUM.
Make sure that the free play locking clip is installed such that one must push
forward, toward the front of the bike, to remove. Otherwise the clip is apt to come
undone while riding.
To adjust (see figure 2b):
1. Loosen the lock nut (10mm).
2. Undo the free play locking clip from around the brake adjustor (plunger),
with your hand by pushing it forward.
3. Slide the pin of the locking free play locking clip from the brake lever
4. Adjust as needed by rotating the clevis on the end of the adjustor
(plunger).
NOTE:
Turning the clevis Clockwise will lengthen the adjustor (plunger), removing free
play from the system, and turning the clevis Counter-Clockwise will shorten the
adjustor (plunger) adding free play to the system.

15
Air Filter Cleaning
Figure A1
•Remove the seat (unscrew the knob under the seat & rear fender)
•Squeeze the two tabs together as shown in figure A1 and pull the wire
retainer up and out of the air box
•The filter may now be pulled from the airbox
•Clean the airbox of dirt and clean the filter sealing surface of the old sealing
grease.
CAUTION:
Pay particular attention to clean any particles from the airbox between the filter
location and the carburetor.
NOTE:
Cobra has available a carburetor cover that allows easy cleaning of the airbox.
1. Remove the air boot
2. Install the cover (RCMU0109) over the carburetor inlet
3. Spray out the airbox.
Do not clean the air filter with gasoline or other highly volatile petroleum product.
Diesel fuel or kerosene would be preferred but caution should still be taken. Hot
soapy water works well.
1. Clean the filter in hot soapy water to remove all dirt particles.
2. Allow it to dry thoroughly.
3. Saturate with filter oil and remove excess.

16
NOTE:
It’s very important to oil your filter consistently each time because varied amounts
of oil will change your carburetor jetting.
4. Apply grease to the black sealing surface of the filter and reinstall as in figure
A2.
Figure A2
5. Squeeze the two finger tabs together on the wire retainer and install into the
airbox while aligning the bottom guiding tabs “legs” with the arrows on the
filter (figures A3 & A4)
Figure A3 Figure A4
6. Push the wire retainer down until it bottoms
CAUTION:
If the side arms do not align with the associated holes it is quite likely that the
legs did not make it into the holes. Realign and try again.

17
7. Press each side arm into their respective holes one at a time with each finger
tab.
Figure A5 Figure A6
8. When properly installed, the filter and retainer should look like figure A7, with
the filter material extending beyond the perimeter of the wire retainer
Figure A7
NOTE:
Make sure you change or clean your filter after each moto. We recommend
carrying multiple filters in your toolbox, one for each practice session and moto.
Fork Oil Replacement
Tools required
•Two 19 mm wrenches or sockets

18
•4 & 5 mm hex key (Allen wrench)
•25mm wrench or socket
•7 wt fork oil
Disassembly procedure
1. Remove the front wheel (19 mm wrench).
2. Remove the brake caliber from the fork leg (4 mm hexkey).
3. Loosen the fork caps (25mm 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.
e. Work the damper rod up and down several times.
f. Allow it to drain completely.
Assembly procedure
1. Fill the fork leg with 4.4 oz (130 ml) 7 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).

19
Parts
Parts –Airbox & Inlet System
Figure 5
Coolant System
REF # PART # DESCRIPTION
1RCKG0001 AIRBOX
2HCBF0616 M6X16 FLANGE HEAD BOLT
3RCKG0512 AIR FILTER
4RCKG0503 FILTER RETAINER
5TCKG0004 MUDFLAP –AIRBOX
6TCKG0105 BRACKET –MUDFLAP
7HCBB0612 M6X12 BUTTON HEAD BOLT
8MCKGHO03 HOSE CLAMP –AIRBOX TO BOOT
9RCKG0505 AIR BOOT
10 MCKGHO01 HOSE CLAMP –BOOT TO CARB
11 MCKGHO04 HOSE CLAMP –CARB TO MANIFOLD
12 ECKG0203 INLET MANIFOLD
14 ECKG0202 REED CAGE ASSEMBLY WITH REEDS
NOT SHOWN ECKG0205 REED REPLACEMENT KIT
15 ZCMU0132 GASKET –REEDS TO ENGINE
16 HCBC0625 M6X25 SOCKET HEAD CAP SCREW
17 HCWF0601 6MM FLAT WASHER
18 RCCM1301 VELOCITY STACK