Cobra 2005 cm50 Service Manual
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Cobra 2005 cm50 Service Manual

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  • Page 2 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.
  • Page 3 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.

  • Page 4: Table Of Contents

    Table Of Contents General Information ....................5 Specifications - General ..................5 Specifications - Torque Values ................6 Optional Components ..................7 Break-In Procedure ................... 8 Starting Procedure .................... 9 General Tips ....................10 Maintenance ....................... 11 Schedule & Tips ....................11 Replacing Transmission / Clutch Lubricant .............
  • Page 5 Parts – Front Brakes ..................33 Parts – Front Wheel ..................34 Parts – Plastic Bodywork & Seat ..............35 Parts – Rear Brake ..................36 Parts – Rear Wheel ..................37 Parts – Shock ....................38 Parts – Swingarm Assembly................39 Service ........................

  • Page 6: General Information

    Float Height 16mm + 0.5mm (0.63” + 0.020”) Transmission Speed / Clutch Single / Cobra 3 shoe Final drive ratio 13/38T or 14/38 T Chain Transmission / clutch oil type Cobra Venom 3 Shoe Clutch Milk Quantity 235 ml (8.0oz)

  • Page 7: Specifications - Torque Values

    Chassis Front tire 2.50 – 10 Pressure 15 psi minimum Rear tire 2.75 – 10 Pressure 15 psi min. (20 psi for hard pack or rocky conditions) Front fork Marzocchi 32mm Fork oil type SAE 20 weight Fork oil amount 200 ml (6.8 oz) oil change, 220 ml (7.4 oz) rebuild Collapsed fork oil height 70 mm (2.75”) spring in, no spacer Specifications - Torque Values Torque Value...

  • Page 8: Optional Components

    Optional Components Call your dealer, or the factory, for details • Carburetor jets • Pre-filter for the airbox • Sprockets o Front o Rear • Suspension Springs Weight of Rider (lb) Fork Spring Shock Spring Less than 38 (light) KCMZ0012A SCMUOH04 (12 lb/in, 2.10 N/mm)) (275 lb/in) red...

  • Page 9: Break-In Procedure

    Break-In Procedure Your Cobra CM50 is a close-tolerance high performance machine and break-in time is very important for maximum life and performance. The CM50 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.

  • Page 10: Starting Procedure

    (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.

  • Page 11: General Tips

    General Tips 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...

  • Page 12: Maintenance

    • Every 10 hours of operation Replace the fork oil. Have the shock oil replaced by a Certified Cobra Mechanic. 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.

  • Page 13: Replacing Transmission / Clutch Lubricant

    Replacing Transmission / Clutch Lubricant Tools needed: • 225 ml (7.6 oz) Cobra Venom 3 Shoe Clutch Milk (Part # MCMUGF01). • 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.

  • Page 14: Chain Adjustment

    5. Reapply oil from oil fill plug 235 cc Cobra Venom 3 Shoe Clutch Milk 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.

  • Page 15: Front Brake Adjustment

    3. If the chain requires adjusting, loosen the axle with a 19 mm wrench and tighten the chain by rotating the adjustor bolts clockwise (CW) or loosen the chain by rotating the adjustor bolts (CCW). 4. Retighten the axel bolt to 25 ft-lb (34 Nm). 5.

  • Page 16: Rear Brake Adjustment

    Rear brake adjustment Tools recommended for rear brake maintenance: • 10mm open end wrench There are 2 adjustments on the brake. Figure 5, adjust brake lever free height Figure 6, adjust brake lever ‘free play’ From the brake lever: 6. Loosen the 10mm nut on the back of the brake pedal. 7.

  • Page 17: Fork Oil Replacement

    7. Saturate with filter oil and remove excess. NOTE: The Cobra is equipped with a special designed Air box. It is very important to keep the air filter 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.
  • Page 18 1. Remove the front wheel. 2. Remove the fork legs from the triple clamps. 3. Perform the following on one leg at a time. 4. Using your hands, remove the black rubber plug from the top of the fork leg exposing the white plastic cap.

  • Page 19: Parts

    Parts Parts – Airbox and Inlet System Figure 7 Airbox and Inlet System REF # PART # DESCRIPTION ZCMU0032 GASKET – REED TO CYLINDER ECKG0205 REED VALVE ZCMU0031 GASKET – MANIFOLD TO REED ECKG0203 INLET MANIFOLD HCWF0601 6MM FLAT WASHER HCBC0625 M6X25 SOCKET HEAD CAP SCREW MCKGHO04...

  • Page 20: Parts - Bars And Controls

    Parts – Bars and Controls Figure 8 Bars and Controls REF # PART # DESCRIPTION FCMU0066 THROTTLE ASSEMBLY FCMU0068 THROTTLE COVER TCMU0008 GRIPS (SET OF TWO) FCMU0067 THROTTLE CABLE FCMU0033 KILL SWITCH ASSEMBLY KCMZ0001 M8X50 SOCKET HEAD CAP SCREW (4 REQ’D) KCMZ0003 LOWER HANDLE BAR CLAMP (2 REQ’D) KCMZ0002...

  • Page 21: Parts - Carburetor

    Carburetor Parts - REF. # PART # DESCRIPTION Carburetor RCCM0001 COMPLETE CARBURETOR 14MM RCMU0305 CARB SLIDE RCMU0601 NEEDLE RCMU0002 ATOMIZER RCMU0092 MAIN JET RCMU0055 PILOT JET CHOKE JET RCMU0301 FLOAT RCMU0102 RUBBER CABLE CAP SEAL RCMU0003 CABLE ADJUSTOR RCMU0006 TOP CARB SCREW RCMU0106 CARB TOP ZCMU0007...

  • Page 22: Parts - Coolant System

    Parts – Coolant System Figure 10 Coolant System REF # PART # DESCRIPTION ECMU0061 RADIATOR WITH CAP MCMUHO02 RADIATOR HOSE LEFT MCMUCL02 HOSE CLAMP ECHA0003 MOUNTING BRACKET – RADIATOR BOTTOM HCBC0607 M6X50 SOCKET HEAD CAP SCREW HCNL0601 6MM LOCK NUT MCKGGR00 GROMMET –...

  • Page 23: Parts - Electrical System

    Parts – Electrical System Figure 6 Electrical System REF # PART # DESCRIPTION IAMU0001 COIL W/SPARK PLUG CAP ECMU0065 SPARK PLUG, CHAMPION (8339-1) ECMU0067 OPTIONAL HOTTER PLUG (8332-1) ECMU0066 OPTIONAL COLDER PLUG (8904-1) FCMU0033 KILL SWITCH ASSEMBLY HCBC0516 SCREW, M5 X 16 (2 PER) HCCN0000 5MM CLIP NUT (2 PER) IAMU0003...

  • Page 24: Parts - Engine - Bottom End And Transmission

    Parts – Engine – Bottom End and Transmission Figure 7A Engine Bottom End and Transmission REF # PART # DESCRIPTION ECKG0017 CRANKCASE, IGNITION SIDE no bearings ECMU0020L BEARING, TRANSMISSION PRECISION ECKG0004 SNAP RING, WATER PUMP ZCMU0501 GASKET, CRANKCASE ECMU0106 SECONDARY SHAFT, TRANSMISSION WITH GEAR ECMU0017 SEAL, CRANKSHAFT ECMU0016...

  • Page 25: Parts - Engine - Clutch And Kick Starter

    Parts – Engine – Clutch and Kick Starter Figure 13 Engine – Clutch and Kick Starter REF # PART # DESCRIPTION ECMU0027 CLUTCH COVER COMPLETE WITH KICK LEVER ZCMU0030 CLUTCH COVER GASKET ECMU0207 KICKSTART GEAR SMALL HCBC0608 M6X55 SHCS CLUTCH CVR SCREW LNG (2 REQ’D) CENTER HCBC0606 M6X45 SHCS CLUTCH COVER SCREW SHORT (4 REQ’D) ECMU0037...

  • Page 26: Parts - Engine - Ignition And Water Pump

    Parts – Engine – Ignition Water Pump Figure 7C Engine – Ignition and Water Pump REF # PART # DESCRIPTION ECKG0001 IGNITION COVER ZCKG0101 IGNITION COVER GASKET HCBC0445 M4 x 45 SOCKET HEAD (4 REQ’D) ECKG0170 WATER PUMP BELT ECKG0175 WATER PUMP PULLEY, FAN TYPE - DRIVEN ECMU0180 BELT RETAINER...

  • Page 27: Parts - Engine - Top End

    Parts – Engine – Top End Figure 15 Engine – Top End REF # PART # DESCRIPTION ECKG0041 CYLINDER ZCKG0501 BASE GASKET ECMU0043 PISTON KIT ECMU0055 PISTON RINGS (2 PER SET) ECMUSR00 SNAP RING FOR PISTON (2 REQ'D) ECKG0012 WRIST PIN ECMU0077 BEARING, WRIST PIN ZCMUOR07...

  • Page 28: Parts - Exhaust System

    Parts – Exhaust System Figure 16 Exhaust System REF # PART # DESCRIPTION XCCM2004 2004 CM EXHAUST PIPE ZCMUOR30 HEADER PIPE O-RINGS (2 REQ’D) XCMU0005 EXHAUST SPRING - SHORT MCMUGR06 PIPE GROMMET MALE MCMUGR07 PIPE GROMMET FEMALE MCMUSP02 PIPE GROMMET SPACER HCWF1478 PIPE GROMMET WASHER HCBF0635...

  • Page 29: Parts - Forks & Triple Clamps

    Parts – Forks & Triple Clamps Figure 17 Front Forks and Triple Clamp REF # PART # DESCRIPTION KCMZ0029 OUTER FORK LEG – RIGHT (NON BRAKE) SIDE KCMZ0131 OUTER FORK LEG ASSY – RIGHT WITH SEAL & SWIPER NOT SHOWN KCMZ0020 OUTER FORK LEG –...

  • Page 30: Parts - Forks - Leg Assembly

    Parts – Forks – Assembly Figure 18 REF # PART # DESCRIPTION KCMZ0004 FORK PLUG – BLACK KCMZ0007 SNAP RING FOR FORK CAP KCMZ0008 INNER FORK CAP - WHITE KCMZ0009 O-RING UNDER FORK CAP KCMZ0111 PRELOAD SLEEVE KCMZ0012 FORK SPRING KCMZ0013 SWIPER KCMZ0014...

  • Page 31: Parts - Frame - Mounting Hardware I

    Parts – Frame – Mounting Hardware I Figure 19 Frame – Engine, Tank, and Pipe Mounts, Brake Snake REF # PART # DESCRIPTION FAMU0004 FRAME 2004 CM50 HCBH1403 SWINGARM BOLT HCNL1402 SWINGARM LOCK NUT (M14X1) HCBH0880 M8X80 SOCKET HEAD CAP SCREW HCNL0801 8MM LOCKNUT MCMUGR06...

  • Page 32: Parts - Frame - Mounting Hardware Ii

    Parts – Frame – Mounting Hardware II Figure 20 Frame – Seat, Fender, Right Side Panel, Brake Pedal, Silencer & Shock Mounts REF # PART # DESCRIPTION FAMU0004 FRAME 2004 CM50 HCBB0635 M6X35 BUTTON HEAD CAP SCREW HCHA0003 6MM CLIPNUT HCBF0620 M6X20 FLANGE HEAD BOLT HCNF0602...

  • Page 33: Parts - Frame - Mounting Hardware Iii

    Parts - Frame – Mounting Hardware III Figure 21 Frame – Radiator, Footpeg, Chain Roller, and Airbox Mounts REF # PART # DESCRIPTION FAMU0004 FRAME 2004 CM50 ECHA0003 MOUNTING BRACKET – RADIATOR BOTTOM HCBC0607 M6X50 SOCKET HEAD CAP SCREW HCNL0601 6MM LOCK NUT MCKGGR00 GROMMET –...

  • Page 34: Parts - Front Brakes

    Parts – Front Brakes Figure 22 Front Brakes REF # PART # DESCRIPTION BCMU0300 BRAKE HUB – FRONT BCMU0113 BRAKE ARM – FRONT BCMU0005 CABLE CLAMP, WASHER & NUT BCMU0006 CABLE ADJUSTOR BCMU0110 BRAKE SHOE (PAIR) BCMU0010 SPRING – BRAKE RETURN BCMU0011 PUSH NUT –...

  • Page 35: Parts - Front Wheel

    Parts – Front Wheel Figure 23 Front Wheel REF # PART # DESCRIPTION WAMU0300 FRONT WHEEL COMPLETE WCMU0250 FRONT TIRE 10X2.50” WCMUTU10 TUBE 10” WCMU0014 FRONT AXLE HCWF1202 WASHER – AXLE WCMU0023 FRONT WHEEL SPACER WCMU0020 BEARING – WHEEL (2 REQ’D) WCMU0004 SPACER –...

  • Page 36: Parts - Plastic Bodywork & Seat

    Parts – Plastic Bodywork & Seat Figure 24 Plastic and Seat REF # PART # DESCRIPTION NOT SHOWN TCMU0020 GRAPHIC KIT TCHA0107 FRONT FENDER NOT SHOWN HCBF0616 FENDER BOLT, M6X16 FLANGE HEAD (4 REQ’D) TCMU0005 NUMBER PLATE - FRONT NOT SHOWN HCBF0625 M6X25 FLANGE HEAD BOLT –...

  • Page 37: Parts - Rear Brake

    Parts – Rear Brake Figure 25 Rear Brake System REF # PART # DESCRIPTION BAMU0301 BRAKE PEDAL BCMU0008 CABLE – BRAKE SNAKE BCMU0009 CRIMP – BRAKE SNAKE HCBB0803 M8X40 BUTTON HEAD SCREW HCNL0801 8MM LOCK NUT HCBH0602 M6X25 HEX HEAD BOLT (BRAKE STOP ADJUST) HCNS0601 6MM NUT BCCM0105...

  • Page 38: Parts - Rear Wheel

    Parts – Rear Wheel Figure 26 Rear Wheel REF # PART # DESCRIPTION WACM0100 WHEEL COMPLETE – REAR WCMU0275 TIRE – REAR 10X2.75” WCMUTU10 TUBE – 10” PCMU0137 SPROCKET – 37T PCMU0059 RUBBER SPROCKET DAMPERS NOT SHOWN WCMU0006 SPACER – SPROCKET DAMPER WCMU0016 REAR AXLE HCPA0002...

  • Page 39: Parts - Shock

    Parts – Shock Figure 27 REAR SHOCK REF# PART # DESCRIPTION SACM2004 SHOCK ABSORBER SCMUOH05 SPRING – STANDARD (285 lb/in) SCMUOH04 SPRING – LIGHT (275 lb/in) SCMUOH06 SPRING – HEAVY (295 lb/in) HCBC1001 M10X45 SHCS...

  • Page 40: Parts - Swingarm Assembly

    Parts – Swingarm Assembly Figure 34 Swingarm REF # PART # DESCRIPTION GACM2004 SWINGARM ASSEMBLY (CONTAINS ITEMS 1 - 13) GAMU0004 SWINGARM GCMU0001 SWINGARM BUSHING (SINGLE PIECE) GCMU0009 SPACER - PIVOT TUBE GCMU0017 CHAIN GUARD HCFH0516 M5X16 FLAT HEAD SCREW HCWF0501 5MM FLAT WASHER HCNL0501...

  • Page 41: Service

    • 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.

  • Page 42: Engine Removal

    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. Engine is Fresh Engine Down on Power Engine NEEDS Rebuilt...

  • Page 43: Complete Engine Disassembly Procedure

    Remove the clutch nut / starter gear that holds on the clutch (special tool available, contact your local dealer). With the Cobra flywheel / clutch puller (#MCMUTL68), remove the clutch from the crankshaft (details in Clutch Service portion of this manual).

  • Page 44: Splitting The Cases

    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.

  • Page 45: Engine Assembly

    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.
  • Page 46 Figure 25 Figure 26...
  • Page 47 10. Insert dowel pins in the left side case as shown in figure 27. Figure 8 11. Clean the gasket mating surfaces with acetone 12. Apply gasket sealer (ThreeBond 1104 gasket material or equivalent) to the mating surfaces of both crankcase halves). NOTE: Gasket material is only required around the crankcase, and not the transmission.
  • Page 48 Figure 28 16. Torque to 12 Nm (105 in-lb) in the pattern shown in figure 28. 17. Trim away any excess gasket material. NOTE: Check engine mount holes for excess material that may cause problems in engine installation. 18. Install the piston with new wrist pin bearing and, pin and clips. CAUTION: Be sure to align the piston such that the arrow on the top piston surface points to the exhaust (front of bike/engine) and put assembly lube on the connecting rod...
  • Page 49 Figure 30 24. Install cylinder head insert. NOTE: A light application of silicone grease can help hold the o-rings into position during assembly. 25. Pressure test the engine insuring an acceptable leak down rate. 26. Install O-rings as shown in figure 31. Figure 31 27.

  • Page 50: Clutch

    3. Remove the clutch nut (not left hand thread) on the end of the crankshaft with the clutch nut removal tool. 4. Attach the COBRA CLUTCH PULLER. There are three 6mm clutch puller holes located on the ends of the center hub. (figures 32 & 33) You must use a draw type puller to remove the clutch.
  • Page 51 Do not use a jaw type puller or use the 6mm tapped holes as jackscrews or you are likely damage the clutch or drum. 5. If necessary apply heat to the center clutch hub. CAUTION: Do not heat the crankshaft threads or the aluminum shoes. 6.
  • Page 52 Figure 34b Clutch adjustment washers Your Cobra comes stock with a single flat washer at the bottom of the spring washer stack. The thickness of that flat washer is 0.056” (1.4mm). Cobra offers several thicknesses of thin adjustment washers that allow clutch engagement tuning.
  • Page 53 • 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.
  • Page 54 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 which is recommended or to your own specialized stack. CAUTION: It is also important that all three shoes are stacked the same. (See figure 34) 2.

  • Page 55: Ignition

    Prior to tightening the six clutch cover bolts, press the kick lever down to ensure proper kick gear alignment. Figure 40 9. Put pipe back on and add oil (235 ml (8.0 oz) Cobra 3 Shoe Clutch Milk (Part # MCMUGF01). Ignition Stator care Stator failure will result from running the bike hot.

  • Page 56: Ignition

    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.
  • Page 57 6. Set the dial indicator to zero 7. Turn the crankshaft clockwise until the dial indicator reaches 0.045” (1.14mm) from top dead center. 8. Line up the lines on the stator and the rotor (figure 37). Otherwise loosen the three 5mm bolts to adjust the stator. 0.045”...

  • Page 58: Cooling System

    The air stream running through the radiator cools the radiator fluid. Therefore dirty radiators additionally reduce the cooling effect. Cobra has tested numerous brand name automotive and racing coolant / antifreeze solutions and has found Liquid Performance Propylene Glycol based Mini Coolant / Antifreeze to have the greatest effect on reducing cylinder head temperatures.
  • Page 59 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.
  • Page 60 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 43 14.

  • Page 61: Fuel & Air System

    Fuel & Air System Carburetor: Tools recommended for Carburetor carburetor service: • Small flat head screwdriver REF. # PART # DESCRIPTION RCCM0001 COMPLETE CARBURETOR 14MM • WD-40 RCMU0305 CARB SLIDE • 8mm socket RCMU0601 NEEDLE RCMU0002 ATOMIZER RCMU0092 MAIN JET RCMU0055 PILOT JET CHOKE JET...
  • Page 62 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.
  • Page 63 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 stock carburetor settings from the factory are: • 55 pilot jet • 92 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;...

  • Page 64: Exhaust

    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 figure 47) Figure 51 The presence of light indicates that the reeds should be replaced, or possibly turned over.

  • Page 65: Wheels & Tires

    • 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.

  • Page 66: Tuning

    Rear wheel pullers Disassembly: 1. Remove axle, back wheel assembly. 2. Pull the rear wheel pullers out of the back of the swing arm. Figure 53 Rear wheel alignment: Either • Accurately measure the distance from the swingarm pivot to the axle center on each side or •...
  • Page 67 1.3.2. Lower in clamps for improved straight line stability. 2. Rear shock 2.1. Shock spring (optional spring) 2.1.1. Stiffer spring – stiffer throughout the travel. 2.1.2. Less stiff spring – less stiff throughout the travel. 2.2. Compression damping (optional valve) 2.2.1.

  • Page 68: Rear Shock

    Lower the bike if the rider has difficulties touching the ground. Rear shock The rear shock on your Cobra is adjustable to your riders weight and riding style by changing the spring rate (stiffness) of the spring and / or by changing the damping valves.

  • Page 69: Gearing

    Gearing For a bike with a centrifugal clutch, it’s better to be geared too low than too high. What happens with improper gearing? • Poor performance • Not enough top end speed • No snap • Over heat clutch • Premature failure of engine seals, bearings, &...
  • Page 70 Sprocket Gear Ratio 2.20 2.27 2.33 2.36 2.40 2.43 2.47 2.50 2.53 2.54 2.57 2.60 2.62 2.64 2.67 2.69 stock 2.71 2.73 2.77 2.79 2.80 2.85 2.86 2.92 2.93 3.00 3.00 3.08 3.15 3.23 Ratio Write © Cobra R&D 2004...

  • Page 71: Carburetion

    Carburetion Although your Cobra is sent from the factory with the carburetor jetted for optimal performance, you may find it necessary to adjustment your particular jetting due to current weather conditions, altitude, fuel variations, and/or engine modifications. CAUTION: Proper jetting is very important for engine performance and engine life.
  • Page 72 Perform all jetting changes on a motorcycle that has been warmed up to proper operating temperature. The carburetor on your Cobra motorcycle is quite adjustable. Figure 59 shows its range of adjustment and in particular what adjustable component affects what range of operation (specifically throttle position).

  • Page 73: Troubleshooting

    TOP END JETTING: Adjust for clean full throttle acceleration Jet your top end (main jet) based on the acceleration of your Cobra Motorcycle on the longest straight at the track. Observe any of the lean or rich symptoms (spark plug appearance and bike performance) listed above and change your jetting accordingly.
  • Page 74 a) Stator bad b) Carburetor diffuser plate upside down (install like a skirt) c) Plugged fuel petcock d) Silencer core tube broken 5) Engine won’t start a) Fuel None in tank ii) Is sour or bad b) Carburetor is dirty c) Ignition Spark plug fouled ii) Wrong spark plug installed (8339 Champion to be used on ’04 or later &...

  • Page 75: Index

    Index Air Filter Maintenance ....15 Front Forks Airbox Service ........68 Front Forks: ........68 Parts .......... 18 Bars and Controls ......19 Front Wheel Parts ......35 Break-In .......... 8 Fuel System Carburetor Service ........61 Gearing ......... 69 Parts ..........
  • Page 76 Front Brake ....... 34 Spark Plug Front Wheel ....... 35 Recommended ......5 Ignition & Water Pump ....26 Specifications ........5 Inlet ........... 18 Plastic & Seat ......36 torque values ....... 6 Rear Brake ........ 37 Starting ..........9 Rear shock ........

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