Cobra Electronics King 2003 User Manual

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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

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.

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

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)

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)

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.

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.

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.

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.

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.

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.

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.

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.

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).

Engine Service / Parts

REF. #

PART #

DESCRIPTION

REF. #

PART #

DESCRIPTION

CAKG0002

Clutch, Complete

ZCKG0002

Gasket, Base

CAKG0004

Shoes, Clutch w/ Washer Springs

ECKG0041

Cylinder, 50cc

CAMU0008

Spring Set, Washer type for Clutch

ZCMUOR07

Oring, Exhaust Flange

CCMU0031

Arbor for 3 Shoe Clutch

ECKG0015

Exhaust Flange

ECMU0018

Nut, Crankshaft Starter

HCBC0602

Screw, 6x20

ECMU0033

Clutch Hub w/ Gear

ECMU0008

Stud, Cylinder

ECMU0040

Clutch to hub spacer

ZCMUOR03

Oring, Cylinder head, Small

ECDC0105

90 Degree Crankcase Vent

ZCMUOR05

Oring, Cylinder head, Medium

ECMU0017

Seal, Crankshaft

ECKG0121

Cylinder Head Dome-Insert

ECMU0016

Bearing, Crankshaft

ECMU0403

Spring, Kickstarter Return

ECMU0001

Bearing, Trans., Secondary Gear

HCNS1401

Nut, 1/4-20

ECMU0020

Bearing, Trans., Precision

ZCMUOR02

Oring, Cylinder head, Large

ECMU0105

Gear, Trans., Primary

ZCMUOR08

Oring, Cylinder head

HCNS1202

Nut, 1/2-20, Left Hand

56A

ZAKGOR02

Oring Kit, Top End

ECKG0018

Crankcase, Clutch side

ECKG0025

Cylinder Head - Outer Cap

ECMU0131

Water Elbow

HCWF1401

Washer, 1/4"

HCBH0805

Screw, M8x12mm

ICMU0006

Rotor

ECMU0103

Shaft, Trans., Secondary w/gear

ICMU0007

Stator

ECMU0104

Shaft, Trans., Output w/gear

60A

MCKGGR00

Grommet, Engine case

ECKGBR01

Bearing, Trans., Output shaft

ECKG0073

Impeller, Waterpump

ZCKG2001

Gasket, Crankcase

ECKG0074

Seal, Waterpump

HCDP1401

Dowel, for Engine Cases

ECKG0203

Intake Manifold

ECMU0038

Crankshaft, Welded and Balanced

ZCMU0032

Gasket, Reed to case

ECKG0017

Crankcase, Ignition side

ZCMU0031

Gasket, Intake to Reed

ECKG0004

Snap Ring, Int. for Water Pump

ECKG0202

Reed Assembly

ECKGSE01

Seal, Output shaft

66A

ECKG0204

Reed Kit

HCBC0606

Screw, M6x45

ZCKG0101

Gasket, Ignition Cover

HCBC0604

Screw, M6x35

ECKG0001

Cover, Ignition

28A

HCBC0603

Screw, M6x30

HCBC0802

Screw, 8-32x1-3/4

HCBC0608

Screw, M6x55

ECMU0043

Piston Kit

PCKG0013

Sprocket, 13T for output shaft

70A

ECMU0055

Piston Ring

30A

ECKGSR03

Snap Ring, Ext., for output shaft

ECKG0012

Wrist pin

HCWP0001

Washer, Stator

ECMU0077

Bearing, Wrist Pin

HCBH0803

Screw, 8-32x7/8

ECMUSR00

Snap Ring for Piston

HCBC0801

Screw, 8-32x1-1/2

ECMUSP01

Spring, Kick Start Dog

HCNS1001

Nut, 10mm

ECMU0207

Gear, Kickstarter, Small

ECKG0042

Pulley, Waterpump-Crank

ZCMU0030

Gasket, Clutch Cover

ECKG0070

Belt, Waterpump

ECMU0205

Kick Starter Rubber

HCBB0001

Screw, 10-32x1/2"

HCWC0000

Gasket, Copper

37A

HCBC1033

Screw, 10-32x3/4"

HCBH0805

Screw, M8x12mm

HCWL0001

Washer

ECMU0204

Kick Starter Dust Shield

ECMU0080

Belt Retainer

ZCMU0001

Gasket, Oil fill plug

ECKG0075

Pulley, Waterpump-Fan

ECMU0037

Oil fill plug

HCSS8201

Screw, 8-32x3/8

ECMU0202

Kickstarter Lever

ECKG0072

Bearing, Waterpump

ECMU0027

Kickstarter, complete

ECKG0141

Shaft, Waterpump

ECMU0003

Brass Clutch Bushing

2003 KING ENGINE ASSEMBLY REFERENCE DRAWING

Figure 5

Trained technicians with precision gauging and proper assembly fixtures carefully assemble all Cobra engines to specific clearances. If you feel you have the skills, and the appropriate tools, to perform the following service tasks please follow the instructions closely. The part numbers are listed throughout to help you when ordering parts from your local Cobra dealer.

If you don’t feel comfortable with the service work, simply take your engine out of the frame and sent it to:

Cobra Precision Engines

11511 Springfield Road North Lima, Ohio 44452

Cobra has specialized mechanics that will go through the entire engine, replacing gaskets, bolts, any old part that is worn. The engine will be rebuilt using the same precision gauging and assembly fixtures as when it was assembled new. Before leaving, the engines performance will be measured on a dynamometer to ensure that your engine is operating at its highest potential. All this for one low nominal fee. Call (330) 549-9603 for details.

ES1: Engine Service

One method for determining whether the top end of your engine needs rebuilt is to perform a WOT (Wide Open Throttle) kicking compression test. Before performing the procedure please read the caution notes below.

CAUTION:

• There appears to be a wide range of variability in reading compression

gauges across the country.

• The head volume of this Cobra Motorcycle is very small and so requires many

kicks ~20 before you establish the most accurate reading possible.

• Because of the geometry of the spark plug used in this Cobra Motorcycle, the

adapter used with your compression tester must have a similar volume protruding into the combustion chamber to establish an accurate value.

• Length of hose on the compression tester will affect the reading. The shorter

the hose length the more accurate your reading will be.

Because of these difficulties in measuring an absolute compression value, a useful relative value can be achieved by testing your bike’s compression with your own particular gauge after a new top end or when the bike is new so that you know what your particular gauge reads on a ‘fresh’ engine. When it has dropped to 90% of its original value the engine will be down on power and would benefit from a rebuild. When it’s dropped to 80% it really needs rebuilt! Using the table below will help you determine monitor the condition of your top end.

Example

Your Values

Procedure for Compression Testing

1. Shut off the fuel petcock.

2. Install the compression gauge into the spark plug hole.

3. Hold the throttle to wide open, and kick repeatedly (approximately 20 times)

or until the gauge reading does not increase in value with each kick.

Engine is Fresh

Measured Value

110 psi 110 psi * 0.9 = 99 psi 110 psi * 0.8 = 88 psi

Engine Down on Power

Measured Value * 0.9

Engine NEEDS Rebuilt

Measured Value * 0.8

E1: Engine Removal

To service the bottom end and transmission, the engine must be removed from the frame.

Tools required

• 5/16”, 10, 14, 22 mm socket

• 10, 13, 22 mm wrench

• 10, 17 & 19 mm sockets

• 9/64”, 3,4 & 5 mm hex key (Allen wrench)

• 7 mm nut driver, flat or Phillip, screwdriver for hose clamps

• Spring remover

• Flywheel / clutch puller (#MCMUTL68)

• Clutch nut removal tool (Call local dealer for details).

Procedure

1. Remove the seat (4mm hex key).

2. Turn of the fuel at the petcock and disconnect the fuel line.

3. Remove the tank (5 mm hex key & 10 mm socket).

4. Remove the carburetor from the inlet (flat head or Phillips head screwdriver, 7

mm nut driver).

5. Remove the righ t side number plate (3mm hex key).

6. Remove the silencer & pipe (spring remover, 5mm hex, & 10mm wrench).

7. Disconnect the ground wire from the reed cage with a 5 mm hex key

(depending on your ultimate repair, you may want to reinstall the fastener in the inlet.

8. Leaving the coolant lines connected to the engine, remove the radiator from

the frame (5mm hex with 10 mm wrench).

9. Remove the master link from the chain.

10. Remove front engine mount bolt (13 mm socket, 6 mm hex key).

11. To access the swingarm bolt, remove brake lever (13 mm wrench, 5 mm hex

key).

12. Remove the swingarm bolt (22mm socket & wrench).

NOTE: Only drive the swingarm bolt far enough to clear the engine, leave it holding the one side of the swingarm to the frame

13. Remove the engine from the right side of the frame.

14. Locate a suitable container for the engine coolant and remove radiator hoses

from engine (coolant will drain).

NOTE: If the coolant looks to be free of contaminates it may be reused.

NOTE: If you are merely performing a top end service skip ahead to Top End

Disassembly Procedure.

E2: Complete Engine Disassembly Procedure

1. Remove the magneto cover (9/64” hex key)

2. Remove the bolt from the water pump shaft (4mm) and slide off the belt cover

and the water pump belt

3. Using a flywheel holding tool and 14 mm socket remove the nut that secures

the flywheel.

4. Using the Cobra flywheel / clutch puller (#MCMUTL68), remove the flywheel

from the crankshaft.

5. Remove the stator (9/64” hex key).

6. Remove the nut holding the large gear to the transmission input sh aft (19 mm

socket).

7. Remove the special nut / starter gear that holds on the clutch (special tool

available, contact your local dealer).

8. With the Cobra flywheel / clutch puller (#MCMUTL68), remove the clutch from

the crankshaft (details in Clutch Service portion of this manual).

E3: Top End Disassembly Procedure

1. Remove the cylinder head nuts (5/16”).

2. Remove the outer cylinder head.

3. Remove the inner cylinder head.

INSPECTION NOTE:

Inspect the cylinder head for deposits and abrasions.

1. If there are deposits they should be removed a. Black oily deposits (indicating a rich mixture or improper oil

type/quantity) can be removed with solvent

b. Crusty deposits (indicating dirt ingestion) can be removed with

solvent and may require some scraping.

2. Abrasions a. Pitting or erosion indicates detonation and may require cylinder

head replacement, also

i. Retard the ignition timing

ii. Use a higher octane fuel

b. Missing chunks or indentations indicate broken hardware or

ingested items - replace the cylinder head.

4. Remove the cylinder.

Inspect the cylinder bore for abrasions, deposits, and missing coating.

1. If abrasions: scrapes, scratches, pitting, etc… are found, replace the

cylinder.

2. If deposits are all are found a. Clean with muratic acid. b. Once the deposits are removed, inspect for abrasions and missing

surface coating.

i. If there are abrasions or missing coating, replace.

ii. If all looks well, the cylinder may be saved.

Muratic acid can be dangerous. Follow the manufacturers instructions closely.

5. Remove the piston clip with a scribe.

6. Remove the piston pin with a piston pin remover. INSPECTION NOTE:

Inspect the piston for abrasions and deposits on the top and sides and clean or replace as necessary.

E4: Splitting the Cases

1. Remove the fasteners holding the two halves of the crankcase together.

2. Separate the cases with a proper case splitting tool.

CAUTION: Take caution when handling the crankshaft. It is the main power transfer to the rest of the engine. If it is out of alignment, it will cause premature failure of your bearings which can lead to serious damage to the cylinder and the rest of the engine. Do not try to true the crank yourself. Truing the crank should be done professionally.

Cobra trues every crank before it leaves the factory, and also welds the pin to keep it true. If there are any problems send the engine in, or call tech support

(330) 549-9603 to determine what the problem is.

CAUTION:

• If you split the cases, check the gear tooth faces for chapping & signs of fatigue.

• Check the small needle bearings for fatigue. If the bearings are damaged, the engine cases should be checked to make sure the needle -bearing casing didn’t oblong the bearing hole in the case.

• Needle bearings should be replaced every racing season.

E5: Engine assembly

CAUTION: For any seals that are to be installed, apply a light amount of grease to the seals’ ID and a small amount of oil to the OD.

1. Press the three bearings into the respective holes in each case half.

2. Press in the crank seals such that the concave side faces the crank weights.

3. Press in the counter shaft seal (concave side faces inside of transmission)

4. Install the water pump assembly

5. Wire ring retainer

6. Press in the water pump assembly

7. Tap both ways axially then verify easy rotation

8. Press crank into left case half

9. Insert the transmission input shaft and install large drive gear as shown in figures 6 & 7.

NOTE:

If the nut was removed from the input shaft, it will be easier to install and tighten later.

Figure 6

Figure 7

10. Insert dowel pins in the left side case as shown in figure 8.

Figure 8

11. Apply gasket sealer (NAPA Aviation Form-A-Gasket #765-1210 or equivalent) to the mating surfaces of both crankcase halves.

12. Apply the crankcase gasket to the left crank case half being sure to install the gasket behind the connecting rod.

13. Insert the screws with the three longer ones (40mm long) at locations shown.

14. Torque to 9 Nm (80 in -lb) in the pattern shown in figure 9.

15. Install the piston with new wrist pin bearing and, pin and clips.

16. Install the piston rings.

Figure 9

CAUTION: Be sure to align the piston such that the arrow on the top piston surface points to the exhaust (front of bike/engine).

17. Apply gasket sealer (NAPA Aviation Form-A-Gasket #765-1210 or equal) to the cylinder deck areas around the coolant passage and cylinder studs as shown in figure 10.

Figure 10

18. Install the base gasket

19. Install the cylinder being sure that the piston rings are properly aligned with the indexing pins.

CAUTION: Never force the cylinder. If resistance is felt, determine the problem and solve it.

20. Install the cylinder studs and o’rings as shown in figure 11.

21. Install cylinder head insert.

Figure 11

22. Install O’rings as shown in figure 12.

Figure 12

23. Install the cylinder head and torqu e to 9.2 ft-lb (12 Nm)

24. Install stator reinstalling the grommet and wires (snug the bolts).

25. Install the rotor per Rotor Installation section, under the ES4: Ignition portion of this manual.

26. Install the water pump outlet pipe (apply Ultra black Hi-Temp RTV silicon gasket maker to the threads before assembly) before installing the clutch and rotate to a vertical position with the engine resting on a bench

27. Install the clutch per Clutch Installation section in this manual.

28. Install the coolant drain plug with copper washer (11 ft-lb, 15 Nm).

29. Make sure that the exhaust spacer is on the cylinder (53 in -lb, 6 Nm).

30. Install the spark plug with a fresh gasket (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).

31. Install reed and inlet manifold with new gaskets (58 in -lb, 6.5 Nm).

ES3: Clutch

Cobra clutch puller assembly:

Clutch puller diagram

Figure 13

Tools recommended for clutch service:

• 22mm socket

• Universal clutch puller- a universal puller that pulls the clutch, main drive gear

and rotor. (Part # MCMUTL70).

• 5mm T-handle

• Clutch nut removal tool (Call local dealer for details)

• Cobra 3 Shoe Clutch Milk (Part # MCMUGF01)

CLUTCH REMOVAL:

1. Drain the engine transmission oil.

2. Remove the pipe and remove the 6 bolts that hold the kick-starter cover on.

3. Remove the clutch nut (right handed nut) on the end of the crankshaft with a 22mm socket.

4. Attach the COBRA CLUTCH PULLER. There are three 6mm clutch puller holes located on the ends of the center hub. (figures 13 & 14) You must use a draw type puller to remove the clutch.

CAUTION: Do not use a jaw type puller or use the 6mm tapped holes as jackscrews or you are likely damage the clutch drum or clutch.

5. If necessary apply heat to the center clutch hub.

CAUTION: Do not heat the crankshaft threads or the aluminum shoes.

6. Keep tension on the puller as you are heating it.

Figure 14

The clutch will often pop off under tension from the puller and it will be very hot.

CLUTCH WASHER STACKUPS:

Once the clutch is removed, and cool to touch, carefully put it into a vice and remove the center shoulder bolt out of each clutch shoe. You will probably have to heat the center hub again to remove the bolts. Once you get a bolt loosened, carefully remove it with the shoe and observe the way the spring washers are stacked.

CAUTION: It is very important that the clutch stack be reassembled as it was disassembled unless new shoes are being installed then it is important to reinstall per figure 15.

CLUTCH ASSEMBLY REFERENCE DRAWING

REF # PART # DESCRIPTION

1 CAKG0004 Set of three shoes, springs, bolts, flat wash ers & nuts 2 CAMU0008 Set Of three springs, washers, bolts & nuts 3 CAKG0005 Set of three shoes 4 HCBS5603 Single center shoulder bolt

Figure 15 Recommended clutch spring stack. Each ‘spring’ stack contains nine springs (Bellville washers) - six arranged into three ‘flying saucers’, and three arranged in a ‘dished’ arrangement against the flat washer.

Clutch shoe wear:

• If the clutch has been slipping and shows signs of glazing, it is best to replace the shoes. We have found that once the shoes are glazed, even if deglazed with emery paper or a file, the performance is reduced.

• The best way to prevent glazing is by not gearing too high, changing the oil as specified and by not blipping the throttle. Every time you blip the throttle, you are working your clutch springs.

CAUTION: The clutch produces a tremendous amount of heat and when a rider is blipping the throttle. This makes the clutch and clutch springs wear out quicker. This also makes your engine tend to run hotter which decreases engine power and degrades ignition stator efficiency. It is important to train your rider NOT to be a throttle 'blipper'.

CAUTION: Sludge build-up between the spring washers also keeps the clutch shoe from engaging fully and this will cause the clutch to start to slip. So you will need to clean the sludge out or just replace the spring washers and bolts with new ones. How quickly this sludge builds up depends on how often you change your oil and whether your rider is a throttle ‘blipper’.

REF # PART NO. DESCRIPTION

1 ECMU0017 Crank seal 2 ECMU0040 Clutch to hub spacer 3 ECMU0003 Brass bushing 4 ECMU0033 Clutch Hub w/ brass bushing 5 CAKG0002 Clutch Complete w/ Arbor 6 ECMU0018 Clutch nut

Figure 16, Clutch Assembly Drawing

CLUTCH ASSEMBLY:

1. After cleaning or replacing the spring washers, reassemble the stack up of washers.

CAUTION: It is important to reassemble the washer stack to that recommended or to your own specialized stack.

CAUTION:

INSPECTION NOTE:

It is also important that all three shoes are stacked the same. (See figure 15)

2. Clean the threads of the stack bolt and the clutch with contact cleaner removing all old thread locking material.

3. Apply high strength (red) thread lock material to the stack bolt and tighten as tight as possible without stripping the Allen head.

CAUTION: Avoid allowing excess thread lock material to contact the spring washers and the clutch or the clutch is likely to malfunction.

4. Use fine emery paper on the center hole of the clutch and on the tapered section of the crankshaft.

5. Apply a small amount of wicking / bearing retainer (green) thread lock agent to the center tapered section of the crankshaft and taper of clutch arbor.

6. Put the clutch back in.

7. Apply high strength (red) thread locking agent to the threads and install the nut and torque to 40 ft-lb (54Nm) with the special socket (see figure 16).

CAUTION: Use high strength (red) thread locker on the threads of the clutch nut. If you are using an impact socket, just zap it lightly with an air wrench to tighten it because there are only about 4 threads inside the nut and they can be easily stripped. If you are tightening it by hand, you can very carefully use a 3/4" piece of wooden dowel rod inside the exhaust port to block the piston so you can tighten the nut. Do not use something harder than your aluminum piston and do not crush the top of the piston into the ring.

a. There must be in / out play in installed clutch (1.5 mm maximum). b. Excess in/out will cause early crank seal failure. c. A blue clutch drum is worn out from excessive slippage or improper

lubrication.

d. Should be no looseness in clutch shoes.

8. Install the clutch cover taking care to put the two longer bolts in their proper locations and tightening in the order specified in figure 17. (5mm hex key, 5.8 ft-lb, 7.8 Nm).

Figure 17

9. Put pipe back on and add oil (225 ml (7.6 oz) Cobra 3 Shoe Clutch Milk (Part # MCMUGF01).

ES4: Ignition

Stator care:

Stator failure will result from running the bike hot. Following is a list of things that will make your engine run hot.

1. The timing should not exceed the maximum specifications listed.

2. Improper carburetor jetting.

3. Improper spark plug heat range. Never run a hotter plug than the specified spark plug.

4. Clutch slippage. See “CLUTCH” section for causes of slippage.

CAUTION:

• 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. Spray the stator and rotor with CRC 3-36 or WD -40 and let it drip dry or blow it off a little with an air nozzle.

• Ignition will overheat if the gap between the rotor and stator is not large enough. There should be even clearance as the rotor rotates relative to the

stator.

• Non -resistor spark plug caps should be used. Resistor caps will result in a weaker spark that will reduce performance.

• Make sure ground wires are secure. If the bike is not grounded it will not run.

• Make sure connections are free of dirt.

CAUTION: If the engine is hot, it is EXTREMLY important to take the ignition cover off, put a fan on it to let it cool, and spray it with CRC 3-36 or WD -40. If you don’t maintain the ignition, it is destine to burn up the stator. (Stator- Part # ICMU0007)

Timing on the 2003 CM50 is very crucial. Cobra has found that the best place to set it is at 0.050” before Top Dead Center (0.050” before the piston’s highest

point of travel). We do not recommend advancing the ignition timing as it will cause the engine to run very hot, in-turn causing power loss, shortened clutch life, and possibly lead to premature stator failure.

Tools recommended for timing service:

• Compact motorcycle dial indicator

• Universal clutch puller- a universal puller that pulls the clutch, main drive gear

and rotor. (Part # MCMUTL70).

TIMING YOUR IGNITION:

1. Remove the spark plug cap, and sparkplug.

2. Insert the dial indicator into the spark plug hole.

3. Remove the four 8/32” X 1 ¾” bolts from the ignition cover.

4. Remove the water pump belt from the rotor and water pump shaft.

5. Turn the crankshaft counterclockwise until it reaches top dead center.

6. Set the dial indicator to zero

7. Turn the crankshaft clockwise until the dial indicator reaches 0.050” (1.3 mm) from top dead center.

8. Line up the lines on the stator and the rotor (figure 18). Otherwise loosen the three 10X32 bolts to adjust the stator.

NOTE:

If you cannot adjust your stator, you must take the rotor off and readjust the timing settings so the lines line up on the rotor and stator. The rotor is not keyed to the crankshaft.

ROTOR READJUSTING:

1. Use the universal clutch puller on the rotor to remove it.

2. Insert dial indicator (figure 19).

3. Turn the crankshaft counterclockwise so it reaches top dead center.

4. Move the crankshaft clockwise to 0.050” (1.3 mm) before top dead center.

5. Inspect and remove markings, scratches, and thread locker residue from the rotor and crankshaft.

0.050” before

TDC

Figure 18, Lining up the line on the rotor with the line on the stator.

Figure 19, Using a dial indicator to measure piston height for setting ignition timing.

ROTOR INSTALLATION:

1. Use wicking / bearing retainer (green) thread locker on the inside of the rotor, and on tapered part of crankshaft.

CAUTION: It is recommended that you apply the proper thread locking primer to the components that are to receive thread locking material per the manufacturers instructions.

2. Eyeball the lines on the rotor and stator then press the rotor onto the crankshaft firmly (figure 18).

3. Torque the nut on the rotor to 40 ft-lb (54 Nm).

4. Recheck the timing following the procedure of timing your ignition.

5. Install the water pump belt back on.

6. Bolt the ignition cover back on.

7. Put the spark plug back in, and firmly stick the spark plug cap onto the spark plug.

ES5: Cooling System

The water pump in the engine keeps the radiator fluid in circulation throughout the motor. The air stream running through the radiator cools the radiator fluid. Therefore dirty radiators additionally reduce the cooling effect.

Radiator fluid removal:

1. Remove the coolan t drain plug (A) on the front of the engine case (figure 20).

Figure 20

To remove radiator cap:

1. Turn the cap counter clockwise to the first stop and wait there for a few seconds.

2. Push the cap down and turn it further in the same direction and remove the cap. NOTE: Inspect the old coolant for visual evidence of corrosion and abnormal smell.

Fill the radiator up to the bottom of the radiator filler neck with coolant. Install the cap, turning it clockwise about ¼ turn.

Tools recommended for impeller service:

• Flat head screwdriver

• 5mm hex key

• 13mm- hex wrench

• 1/8” hex key

• 9/64” hex key

• 3/32” hex key

• Propane torch

• 3/8” diameter x 8” long steel rod

• Hammer

COBRA IMPELLER SERVICE INSTRUCTIONS

1. Remove exhaust pipe and gas tank (you will be using a propane torch in step 12.

2. Remove radiator cap and drain engine coolant by removing the 13mm- hex head coolant drain plug.

3. If the impeller is damaged or broken completely back flush the coolant system to ensure no solid pieces are in the system.

4. Remove foot brake.

5. Drain engine transmission oil by removing drain screw using a 13mm- hex wrench. (item 2 in the figure below).

6. Remove kick-starter cover using a 5mm hex key. (item 3 six places)

7. Remove clutch and basket.

8. Unscrew water elbow fitting. (Figure 21)

Figure 21

8. Remove ignition cover using a 9/64” hex key (four places)

9. Remove belt retainer screw using a 1/8” hex key. (Figure 22 - item 1)

10. Remove belt retainer, water pump belt and water pump fan pulley.

11. Remove bearing retainer screw using a 3/32” hex key. (Figu re 22 – item 2)

Figure 22

12. Heat engine case around area of impeller lightly with a small Burnsmatic propane torch. Using a 3/8” diameter x 8” long steel rod, tap impeller assembly out of engine as shown in figure 23.

Figure 23

CAUTION: Too much heat can be detrimental to the engine cases.

13. The shaft assembly is serviceable. Use a 1/8” hex key to remove impeller retainer screw. Remove impeller, seal and both bearings. Check shaft for wear in the area of the seal. If there is any sign of wear (like a groove) replace the shaft.

Figure 24

assemble in same order of disassembly. Clean all threads and use green

14. Reinstall new bearings, seal and impeller. Clean all threads and use green (wicking / bearing retainer) thread locker.

15. Using a liberal amount of grease on the outside seal, bearings and inside of case, reinstall bearing assembly by using a 0.500” ID by 1.000” OD steel tube 2” long and tap on end of tube per figure 25.

Figure 25

16. Re(wicking / bearing retainer) thread locker on the belt retainer screw.

ES6: Fuel & Air System

Carburetor:

Tools recommended for carburetor service:

• Small flat head screwdriver

• WD-40

• 8mm socket

REF. # PART # DESCRIPTION

Figure 26

KING Carburetor Ref. Drawing

1 RCMU0305 CARB SLIDE 2 RCMU0601 NEEDLE 3 RCMU0002 ATOMIZER

4 MAIN JET 5 PILOT JET 6 CHOKE JET

7 RCMU0301 FLOAT 8 RCMU0102 RUBBER CABLE CAP SEAL

9 RCMU0003 CABLE ADJUSTER 10 11 RCMU0006 TOP CARB SCREW 12 RCMU0106 CARB TOP

13 ZCMU0007 TOP CARB GASKET 14 RCMU0004 SLIDE SPRING 15 RCMU0205 NEEDLE RETAINER PLATE 16 RCMU0007 NEEDLE CLIP 17 RCMU0204 CHOKE ASS’Y. 2001 CM 20 RCMU0009 FUEL MIXTURE SCREW 21 RCMU0011 IDLE ADJUSTMENT SCREW 25 RCMU0103 FLOAT BOWL GASKET 26 RCMU0107 FLOAT NEEDLE

27 RCMU0012 DIFFUSER 28 RCMU0016 FLOAT RETAINER PIN 29 RCMU0106 FLOAT BOWL 30

RCMU0201 BOTTOM FLOAT SCREW

33 RCMU0269 VELOCITY STACK

Your Cobra is equipped with an adjustable carburetor. Some fine-tuning may be needed according to weather condition and altitude. Proper jetting is very important for engine performance and engine life. Serious damage to the engine can occur if not properly adjusted.

IDLE ADJUSTMENT:

On the left side of the carburetor, there are two adjustment screws. The larger screw with the knurled head is the idle adjustment screw. To raise the idle, turn the screw in clockwise (in 1/4 turn increments) and rev the engine after each adjustment. To lower the idle, turn the screw counter-clockwise.

TOP END JETTING:

Indications that the engine is running too rich (too much fuel for the air) are:

• Engine not revving out or blubbering at high RPMs.

• Engine will not ‘clean out’

• Wet or black spark plug

NOTE: Before changing jetting be sure that the air filter is properly cleaned and has the usual amount of air filter oil. An overly dirty air filter can cause the engine to run rich.

If the engine is running rich on the top end it should be leaned out. Leaning it out can be done by:

1. Changing the main jet to a smaller number.

2. Raising the needle clip (this lowers the jet needle) one notch at a time on the slide.

Indications that the engine is running too lean are:

• Engine cutting out on top end.

• Engine overheating and ultimately seizure.

• White spark plug

CAUTION: It is much safer to operate the engine slightly rich as opposed to slightly lean. This is because an overly rich engine will just run poorly while an overly lean engine will seize, potentially causing an expensive top end rebuild and a DNF.

To richen the carburetor:

1. Change the main jet one number at a time (larger).

2. Lower the needle clip (raising the jet needle) one notch at a time until the engine starts to blubber on the top end, then move the clip back up one notch or until you get the blubber out.

FUEL MIXTURE SCREW

The smaller brass screw that is towards the front of the engine is a fuel mixture screw. This screw will also richen and lean your engine more on the bottom and mid-range. In warmer conditions, turn the screw in. In colder conditions, turn the screw out. Be sure to keep the carburetor very clean and make sure you don't

have water or dirt in the carburetor bowl. Use automotive carburetor cleaner or WD-40 to clean the carburetor inside and out.

STOCK CARBURETOR SETTINGS

The 2003 KING stock carburetor settings from the factory are:

• 65 pilot jet

• 94 main jet

Cleaning the carburetor:

Clean the carburetor in a well-ventilated area, and take care that there is no spark or flame anywhere near the working area; this includes any appliance with a pilot light. Because of the danger of highly flammable liquids, do not use gasoline or low flash -point solvent to clean the carburetor.

1. Make sure the fuel is shut off.

2. Remove the carburetor.

3. Drain the fuel in the carburetor.

4. Disassemble the carburetor.

CAUTION: Do not use compressed air on an assembled carburetor. Or the pressure may deform the float. Do not use a strong carburetor cleaning solution, which could attack the parts of the carburetor; instead, use a mild high cleaning solution safe for plastic parts.

5. Immerse all the metal parts in a carburetor cleaning solution.

6. Rinse the parts in water.

7. After the parts are cleaned, dry them with compressed air.

8. Blow out the fuel passages with compressed air.

9. Assemble the carburetor

10. Install the carburetor onto the motorcycle.

NOTE: The three most common problems with

this carburetor are (figure 27):

1. Installing the carburetor top

backwards, an d

2. The carburetor slide indexing pin

falling out .

3. Either side vent elbow falling out .

Figure 27 Proper carburetor top installation and location of rectangular slide indexing pin and one of the elbows that has been known to fall out.

Reeds:

• The reeds must lay flat on the reed cage.

• If the reed tips aren’t lying flat, replace them immediately.

• The reeds must have a tight seal on the reed cage.

• If the reed is damaged in any way, replace it. This means cracks, chips,

and ruptures. Anything abnormal, replace the reeds.

Take the reed cage out and hold it up to the light and look in through the cage. If you see light between the reed pedals and the frame, then replace the reeds. If you do not see light, then the reeds should be ok. (See figu re 28)

Figure 28

The presence of light indicates that the reeds should be replaced, or possibly turned over.

ES7: Exhaust

The pipe is a crucial element to a motorcycle. Any kinks, dents, or damage done to the pipe will result in a major performance loss.

NOTE: Be sure to take the pipe off, and any carbon that may be built up. Carbon build up is created from exhaust. Exhaust has oils in it, and the oils cling to the walls of the inside of the pipe. Over a long period of time, the diameter of the pipe will decrease, due to carbon build up. So it is essential to clear the residue.

CAUTION: It is important to repack the silencer. Signs of your silencer needing to be repacked are:

• The bike is louder than normal.

• A loss of power.

Chassis Service / Parts

CS1: Wheels & Tires

Rear wheel

Rear wheel dampening Tools recommended for wheel service:

• 13mm socket

• Flathead screwdriver

• 11mm wrench or socket

• 19mm wrench

The Cobra is the only 50cc to have the rear wheel damping system. This feature prevents engine impact shock caused by hard landings. This design allows the cushioned sprocket to move forward and backwards separately from the wheel. After each moto, check the 4 rubber dampers, spacers and bolts for fatigue. You should keep extra rubber dampers in your toolbox (part # PCMU0059). Different sized sprockets are also available.

Watch for bending and warping of the outside rear damper plate. If it is bent or warped, the rubber dampers in the sprockets do not last as long as when using a straight unit. Usually you can straighten the plate with a hammer or just flip it over.

Changing the rubber dampers:

1. Remove the four bolts with the 11mm wrench

2. Take the backing plate off

3. Observe the four rubber dampers, and pull the sprocket upward to remove it.

1. Pop the four rubber dampers out of the sprocket.

2. Push the rubber dampers into the sprocket.

3. Place the sprocket with rubber dampers, onto the aluminum studs.

4. Place backing plate over the dampers and sprocket.

5. Insert the 11mm bolts into the holes and tighten to 18 ft-lb (24 Nm).

Figure 29

Rear wheel pullers

Disassembly:

Figure 30

Rear wheel alignment:

Figure 31

1. Remove axle, and back wheel assembly.

2. Pull the rear wheel pullers out of the back of the swing arm.

1. Measure from the side of the swing arm to the outer edge of the rim and make sure both sides are equal.

2. Adjust the wheel pull bolt on the rear wheel puller to get the distance from the swing arm to the rim about the same.

Front wheel assembly

2003 FRONT WHEEL ASSEMBLY

REF. # PART # DESCRIPTION

1 HCNS1201 12mm AXLE NUT 2 KCKG0029 FORK LEG (NONBRAKE SIDE) 3 WCMU0023 WHEEL SPACER (LARGE) 4 WAKG0005 FRONT WHEEL (COMPLETE) 5 WCMU0001 WHEEL SPACER (SMALL) 6 BCKG0008 FRONT BRAKE MOUNT 7 KCKG0028 FORK LEG (BRAKE SIDE) 8 WCMU0016 REAR AXLE

Figure 32

CS2: Brakes

Front Brakes

The front brake is fully hydraulic. WARNING! Your front brake needs a break-in period to achieve maximum brake

power. 30-40 stops will bring the brake to peak performance. Check before each ride:

• Make sure the brake does not have any leaks by holding the lever in while checking hose con nections.

• Make sure the brake lever pressure is OK by pulling in on the lever and ensuring full braking performance is achieved before the lever touches the handlebar. If this is not the case, pump the lever several times until the lever feels firm.

• Alway s make sure the rotor and brake pads are free from oil and grease. Clean the rotor with mild dish soap or alcohol. Contaminated pads must be replaced.

• Do not remove the brake lever unless you want to bleed the brake!!! The piston will come out along wit h the oil behind it unless you keep it held in the master cylinder.

CAUTION: This brake uses low viscosity mineral oil available from a Cobra Dealer. DO

NOT EVER USE DOT BRAKE FLUID!!! Brake Pad removal procedure:

1) Remove brake caliper using 4mm Allen wrench as shown

2) Remove cotter key from caliper as shown and pull pads out.

Figure 33

Figure 34

3) Brake pads must be checked periodically for wear. They are also available

from a Cobra dealer. The brake pad must be a minimum thickness of 2.5mm. This is measuring the pad + the holder as shown below.

Figure 35

Brake bleeding procedure:

1) Remove brake caliper using 4mm Allen wrench as shown in pad removal procedure. Pry pads outward to fully retracted position.

2) Remove reservoir cap using a Torx T25 wrench as shown. Keep reservoir level.

Figure 36

3. Remove bleed screw on caliper using a 3mm Allen wrench as shown.

Figure 37

4) Attach Bleeding syringe as shown. Pump all air out of system until only clean oil runs out of reservoir.

Figure 38

5) Reinstall reservoir cap. Oil will overflow in the process. This is necessary to ensure no air is in the system.

Remove bleeding syringe and quickly reinstall bleed screw.

CS2: Suspension

Rear Shock

COBRA PART NUMBER DESCRIPTION

SCKGOH01 SPRING CLIP SCKGOH02 SPACER SCKGOH03 BALL JOINT SCKGOH04 SPRING PLATFORM SCKGOH05 LOCKNUT SCKGOH06 SLEEVE SCKGOH07 BUMPER RUBBER

SCKG0H08 SPRING - LIGHT SCKGOH09 SPRING-MEDIUM-STOCK SCKGOH10 SPRING-HEAVY SCKGOH11 ORING FOR BALL JOINT SCKGOH12 ORING FOR REBOUND ADJUSTER SCKGOH13 ORING FOR REBOUND ADJUSTER SCKGOH14 SUPPORT SLEEVE SCKGOH15 CIRCLIP SCKGOH16 PIN FOR REBOUND ADJUST SCKGOH17 ADJUSTMENT KNOB SCKGOH18 SHAFT FOR END EYE SCKGOH19 NUT SCKGOH20 END EYE SCKGOH21 SCREW FOR KNOB SCKGOH22 KNOB FOR ADJUSTMENT

Figure 39

Front forks

Tools recommended for front fork service:

• Flat head screwdriver

• Hammer

• Snap ring pliers

• Seal drivers

• 13mm wrench

• 1 1/8” wrench or socket

• 5 wt fork oil

FORK ASSEMBLY PROCEDURES:

Figure 40

1. Slide swiper (#6) onto lower fork leg.

2. Slide snap ring (#5) onto lower fork leg.

3. CAREFULLY slide seal (#4) onto lower fork leg with spring facing away from snap rin g.

4. Slide bronze bushing (#3) onto lower fork leg.

5. Install Teflon bushing into groove on lower fork leg.

Figure 41

6. Slide the bronze bushing over the Teflon bushing about 1/4" to hold the Teflon in the groove.

7. Insert the lower leg assembly into the upper fork tube about 5-6".

8. Use a seal driver to drive the seal into the upper tube.

9. Install the snap ring. Make sure it is properly seated in the groove.

10. Snap the swiper into the groove in the upper tube.

11. Fill with 4.0 oz (118 ml) 5 wt fork oil (should measure 130 mm (5.1”) from top of tube with spring removed.

12. Install the fork spring

13. Connect the cartridge rod to the cap and tighten to 12 ft-lb (9 Nm).

KING FORK Ref.

CAUTION: The damper rod is hollow and will break if the nut is over tightened (proper torque is 12 ft-lb, 16 Nm).

Figure 42

KING FORK Ref.

Drawing

REF. # REF.

1 1 KAKG0005

KAKG0006

2 2 KAKG0030 FORK CAP 3 3 KCKG0021 FORK LEG - OUTER

4 4 KAKG0028

KAKG0029

5 5 KCKG0027 DAMPER ROD 6 6 KCKG0007 FORK SPRING 7#

KCKG0009

KCKG1200 FORK SPRING 12# 7 7 KCKG0023 CARTRIDGE TUBE 8 8 HCNL5601 LOCK NUT-FORK CAP 9 9 KCKG0032 FORK SPRING GUIDE

10 10 ZCMUOR08 O-RING FORK CAP 11 11 KCKG0033 FORK BUSHING-OUTER 12 12 KCKG0025 CARTRIDGE TOP

14 14 KCMU0008 SWIPER 15 15 KCMUSR23 SNAP RING 16 16 KCMU0007 FORK SEAL 17 17 KCKG0020 FORK BUSHING-INNER 18 18 HCBC0625 BOLT -DAMPER ROD 19 19 KCKG0035 BUSHING-PISTON 20 20 KCKG0026 FORK PISTON

21A 21A KAKG0013

21B 21B KAKG0014

21A 21C KAKG0015

22 22 ZCKGOR10 23 23 KCKG0031 TOP OUT SPRING

24 24 KCKG0024 FORK BOTTOM PLUG

PART # DESCRIPTION

FORK ASSY. BRAKE SIDE FORK ASSY. NON BRAKE SIDE

FORK LEG-INNER BRAKE SIDE FORK LEG-INNER NON BRAKE SIDE

FORK SPRING 9# (STOCK)

BASE VALVE ASSY. (SOFT) BASE VALVE ASSY. MEDIUM (STOCK) BASE VALVE ASSY. (HARD) O-RING - BASE VALVE ASSEMBLY

Because of different rider weights, sizes and riding styles, we offer various suspension options:

See Optional Components section of this manual for details on these and other optional components for your Cobra Motorcycle.

Drawing

Troubleshooting

1) Engine not behaving properly

a) Carburetor top is installed backwards (happens a lot) b) The carburetor slide indexing pin is missing

2) Engine is down on power

a) Clutch engagement is not set properly b) Jetting is incorrect c) Silencer needs repacked d) Exhaust pipe

i) Has excess carbon buildup ii) Has large dent in it

e) Compression is low

i) Piston

ii) Rings f) Reeds are damaged g) Ignition timing is incorrect

3) Engine is excessively loud

a) Silencer needs repacking

4) Engine ‘blubbers’ at high RPMs

a) Jetting too rich

5) Engine won’t start

a) Fuel

i) None in tank

ii) Is sour or bad b) Carburetor is dirty c) Ignition

i) Spark plug fouled

ii) Spark plug cap off

iii) Engine Shut-off ‘kill’ switch is shorted

iv) Bad electrical ground

v) Stator winding damaged d) Exhaust is plugged

6) Engine won’t idle

a) Idle knob needs adjusted

b) Carburetor jets are dirty

Index

Air Filter..............................................13

Brakes

Front ...............................................43

Break-In................................................7

Carburetion

Specifications..................................4

Carburetor.........................................36

Chain

Adjustment.....................................12

Chassis

Specification....................................4

Clutch

Parts List 1.....................................27

Parts List 2.....................................28

Service...........................................26

Clutch Lubricant

Replacing.......................................10

Compression test.............................18

Cooling System.................................32

Cylinder head

torque ...............................................6

Damper..............................................40

Engine

Parts List........................................15

Specifications..................................4

Exhaust..............................................39

Flywheel

Torque..............................................6

Fork oil replacement ........................13

Forks...................................................48

Front

Brakes............................................43

Forks...............................................48

Front Wheel.......................................42

Fuel System

Parts list .........................................36

Service...........................................36

General Tips ........................................9

Ignition

Service...........................................30

Timing.............................................31

Jetting

How To...........................................37

Stock.................................................4

Lubrication

Recommended ...............................4

Maintenance

Schedule..........................................9

Tips...................................................9

Oil

Recommended ...............................4

Optional components.........................5

Parts List

Carburetor.....................................36

Clutch 1..........................................27

Clutch 2..........................................28

Engine ............................................15

Pullers ................................................41

Rear

Shock..............................................47

Rear Brake

Adjustment.....................................12

Rear Wheel

Damper..........................................40

Pullers ............................................41

Reeds.................................................39

Rotor

torque ...............................................6

Shock..................................................47

Spark Plug

Recommended ...............................4

Specifications......................................4

Torque Values.................................6

Starting.................................................8

Stator

torque ...............................................6

Suspension........................................47

Tips.......................................................9

Top End

Service...........................................17

Transmission

Specifications..................................4

Transmission Lubricant

Replacing.......................................10

Troubleshooting................................50

VIN reading .........................................9

WARNING ...........................................2

Wheels

Service...........................................40

Cobra Electronics King 2003 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual