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.
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.
Table Of Contents General Information .........................................................................................................4 Specifications - General..............................................................................................4 Optional Components ..................................................................................................5 Specifications - Torque Values ..................................................................................
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.
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.
Specifications - Torque Values Torque Value Size & Fastener ft-lb in-lb Nm Remarks 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 Engine mount bolts 22 265 30 8 mm Swingarm Pivot 21 250 28 14 mm Intake manifold bolts 4.6 55 6.
Break-In Procedure Your Cobra KING is a close-tolerance high performance machine and break-in time is very important for maximum life and performance. The KING can be ridden hard after the first ½ hour break-in time but it is recommended that no adjustments are made to the carburetion or suspension until the full 8 hours of bike break-in has elapsed.
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.
General Tips 1. 2. 3. 4. 5. 6. Always wear a helmet and other protective riding gear. 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 riders’ foot is not resting on the foot brake while they are riding . Evaluate the bikes jetting only after it has been warmed up to race temperatures. A properly maintained machine is safer, faster, and more fun to ride.
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.
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 down) 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.
M2: Chain adjustment 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 2 M3: Rear brake adjustment Tools recommended for rear brake maintenance: 10mm open end wrench There are 2 adjustments on the brake.
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.
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. 6. 7. 8. Reinstall the for cap into the fork leg (5 ft-lb, 6.
Engine Service / Parts 2003 KING ENGINE ASSEMBLY REFERENCE DRAWING REF.
Figure 5 16
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.
Example Your Values Engine is Fresh Measured Value 110 psi Engine Down on Power Measured Value * 0.9 110 psi * 0.9 = 99 psi Engine NEEDS Rebuilt Measured Value * 0.8 110 psi * 0.8 = 88 psi 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.
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.
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.
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.
Figure 6 Figure 7 22
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. Figure 9 14. Torque to 9 Nm (80 in-lb) in the pattern shown in figure 9. 15.
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.
22. Install O’rings as shown in figure 12. Figure 12 23. Install the cylinder head and torque 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.
ES3: Clutch Cobra clutch puller assembly: Clutch puller diagram Figure 13 Figure 14 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.
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: 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 # 1 2 3 4 5 6 PART NO.
CAUTION: 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.
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.
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.
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.
A 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.
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. (Figure 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 24 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-assemble in same order of disassembly. Clean all threads and use green (wicking / bearing retainer) thread locker on the belt retainer screw.
ES6: Fuel & Air System Carburetor: Tools recommended for carburetor service: • Small flat head screwdriver KING Carburetor Ref. Drawing • WD-40 REF.
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.
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.
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.
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.
Rear wheel pullers Disassembly: 1. Remove axle, and back wheel assembly. 2. Pull the rear wheel pullers out of the back of the swing arm. Figure 30 Rear wheel alignment: 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.
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 connections. • 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.
Figure 33 2) Remove cotter key from caliper as shown and pull pads out.
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.
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 Figure 39 COBRA PART NUMBER DESCRIPTION SCKGOH01 SCKGOH02 SCKGOH03 SCKGOH04 SCKGOH05 SCKGOH06 SCKGOH07 SCKG0H08 SCKGOH09 SCKGOH10 SCKGOH11 SCKGOH12 SCKGOH13 SCKGOH14 SCKGOH15 SCKGOH16 SCKGOH17 SCKGOH18 SCKGOH19 SCKGOH20 SCKGOH21 SCKGOH22 SPRING CLIP SPACER BALL JOINT SPRING PLATFORM LOCKNUT SLEEVE BUMPER RUBBER SPRING - LIGHT SPRING-MEDIUM-STOCK SPRING-HEAVY ORING FOR BALL JOINT ORING FOR REBOUND ADJUSTER ORING FOR REBOUND ADJUSTER SUPPORT SLEEVE CIRCLIP PIN FOR REBOUND ADJUST
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 ring. 4. Slide bronze bushing (#3) onto lower fork leg. 5. Install Teflon bushing into groove on lower fork leg.
13. Connect the cartridge rod to the cap and tighten to 12 ft-lb (9 Nm). CAUTION: The damper rod is hollow and will break if the nut is over tightened (proper torque is 12 ft-lb, 16 Nm). KING FORK Ref. KING FORK Ref. Drawing Drawing REF. REF.
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 ‘bl
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 ....................
