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Cobra Moto CX50 JR Owners, Parts, Service, Tuning

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Summary of Contents for Cobra Moto CX50 JR

  • Page 1 Owners Parts Service Tuning...
  • Page 2 For parts orders, contact your local dealer. To locate your closest Cobra dealer, log on to www.cobramoto.com or call +1 (517) 437 - 9100 Cobra MOTO, LLC 240 Uran Road Hillsdale, MI 49242...
  • Page 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. Motorcycles are generally not covered by homeowner or trailer content insurance, and they typically require their own policy.

  • Page 4: Table Of Contents

    Table of Contents General Information ....................6   Specifications - General ..................6   Optional Suspension Components ..............7   Specifications - Torque Values ................7   Break-In Procedure ..................10   Starting Procedure ..................11   Maintenance ....................... 12  ...
  • Page 5 Parts – Front Wheel ..................41   Parts – Plastic & Seat ..................43   Parts – Rear Brake ..................45   Parts – Rear Wheel ..................47   Parts – Shock ....................48   Parts – Shock - Internal ................... 49  ...

  • Page 6: General Information

    General Information Specifications - General Items CX50 JR Dimensions Wheelbase 36.00” (914mm) Wheel size 10” (254mm) Seat height 23.9” (607 mm) Fuel tank volume .65 gallon, 2530 cc Engine Type 2-stroke, single cylinder, reed valve Cooling system Liquid-cooled, VP Racing: Stay Frosty Coolant Displacement 49.8 cc...

  • Page 7: Optional Suspension Components

    Optional Suspension Components Weight of Rider (lb) Fork Spring Shock Spring KCCJ3218 Less than 38 (light) SCMUOH04 (275 lb/in) red (10 lb/in, .18 kg/mm) KCCJ3221 SCMUOH05 (285 lb/in) 38 – 45 (std) (12 lb/in, .21 kg/mm) yellow KCCJ3225 SCMUOH06 (295 lb/in) 46 to 55 (stiff) (14 lb/in, .25 kg/mm) white...

  • Page 8: Specifications - Torque Values

    Specifications - Torque Values Torque Value Fastener Size & Remarks Loctite ft-lb in-lb Cylinder head nuts M6 X 1.0 Cylinder nuts M8 x 1.0** Crankcase bolts See the next page M6 x 1.0 Spark plug (SP) (SP) (SP) M14 x 1.25 Stator bolts M5 X 0.8 Ignition rotor nut...
  • Page 9 (SP) To apply the proper torque to the spark plug when inserting, first screw the spark plug in until the metal gasket ring causes resistance and then turn another ¼ turn. Engine case torque values Torque the engine case bolts in the pattern shown above. The upper two bolts have a different toque value compared to the others.

  • Page 10: Break-In Procedure

    Break-In Procedure Your Cobra CX50JR is a close-tolerance high performance machine and break-in time is very important for maximum life and performance. The CX50 JR can be ridden hard after the first ½ hour break-in time. Cobra recommends VP Racing: X2 1050 premix oil with high octane pump gas mixed at 32:1 (4 oz of oil to a gallon of gas).

  • Page 11: Starting Procedure

    Starting Procedure Before starting the machine inspect the following:  Tire pressure  Chain tension  Coolant level  Proper wear on chain rollers and sliders  Handlebar tightness  Throttle assembly movement/cable adjustment  Air Filter  Check for loose nuts and bolts ...

  • Page 12: Maintenance

    CAUTION: Make sure your riders’ foot is not resting on the foot brake while they are riding Maintenance A properly maintained machine is safer, faster, and more fun to ride. It is important that you adhere to this maintenance schedule so as to promote the longevity of your Cobra Motorcycle Tips Recommended lubricants:...

  • Page 13: Schedule

    Example, CJRxx17xxx is a 2017 CX50 JR. 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.

  • Page 14: Replacing Transmission / Clutch Lubricant

    o Equalize the pressure in the forks with atmosphere.  Every 2 hours of operation o Replace the transmission oil. o Check the CFD torque  Every 10 hours of operation o Replace the fork oil. o Have the shock oil replaced by a Certified Cobra Mechanic. Replacing Transmission / Clutch Lubricant Tools needed: ...

  • Page 15: Proper Chain Adjustment

    Proper Chain adjustment Tools required for chain adjustment  19 mm wrench or socket  13 mm wrench or socket 1. Make sure that the rear wheel is aligned properly. A properly adjusted chain will have 35mm (1.368”) free movement behind the chain Figure 2 block with no load on the bike.

  • Page 16: Rear Brake Pedal Height

    Rear Brake Pedal Height Brake pedal toe tip height can be adjusted with the nut and adjuster located below the rear brake master cylinder. The free-play is not adjustable on this model. CAUTION: Use a New container of VP Racing: 622 DOT4 Racing Brake Fluid if necessary to add fluid.

  • Page 17: Air Filter Cleaning

    Air Filter Cleaning Tools recommended for air filter maintenance:  #2 Phillips head screwdriver  4 mm Allen wrench  Foam filter oil Procedure 1. Removed the seat with a 4 mm Allen wrench. 2. Remove the filter/air inlet boot from the back of the carburetor with a Phillips screwdriver 3.
  • Page 18 For routine maintenance, the chart below provides suggested service intervals for common procedures: Each Ride 10 hours 20 hours As Needed Bleed excess air Change Oil Change Seal/Swiper Change Bushings...

  • Page 19: Fork Air Bleeding

    Fork Air Bleeding Tools required  3mm hex key (Allen wrench) During normal operation, both fork legs will build up air pressure. This pressure acts as an additional spring so it must be bled on a regular basis to maintain consistent suspension operation.

  • Page 20: Cobra Frictional Drive (V3 Cfd)

    5. Extend the damper rod completely and Compress the fork spring enough to begin threading the fork cap back onto the damper rod. 6. Make sure that the fork cap threads onto the damper rod completely before it makes contact with the jam nut. 7.

  • Page 21: Throttle Cable Strain Relief

    5. If there is slippage below 108 Nm (80 ft-lb) remove the cotter pin and tighten the castle nut on the CFD one more position (it is a left hand thread nut so you must turn it counter clockwise) NOTE: This V3 CFD torque checking method is possible do to with the chain on. Just put the bike on a stand so that the rear wheel can turn freely.

  • Page 22: Parts

    Parts Parts – Airbox and Inlet System Airbox and Inlet System REF # PART # DESCRIPTION TCCJ0013 AIRBOX HCSP0004 SCREW – PLASCREW – ALUMINUM RCCJ0005 AIR FILTER ASSY TCC60008 MUDFLAP MCKGHO01 HOSE CLAMP – BOOT TO CARB MCKGHO04 HOSE CLAMP – CARB TO MANIFOLD RCMU0036 INLET MANIFOLD ECMU0246...

  • Page 23: Parts - Bars And Controls

    Parts – Bars and Controls Bars and Controls REF # PART # DESCRIPTION FAMU0017 HANDLEBAS – MICROBARS – COBRA BEND TCMU0021 GRIPS (SET OF TWO) – MICROGRIPS – FAMU0016 THROTTLE ASSEMBLY – COBRA MICRO FAMU0015 TUBE ASSEMBLY – THROTTLE – 2 PIECE MICRO HCBC0525 M5 X 25 SHCS –...

  • Page 24: Parts - Carburetor

    Parts – Carburetor PILOT JET MAIN JET* RCMU0048 RCMU0088 RCMU0094 RCMU0050 RCMU0089 RCMU0095 RCMU0052 RCMU0090 RCMU0096 RCMU0055 RCMU0091 RCMU0097 RCMU0060 RCMU0092 RCMU0098 RCMU0065 RCMU0093 *Larger and Smaller sizes are available upon request Carburetor REF. # PART # DESCRIPTION RACJ5014 CARBURETOR RCMU0307 GASKET –...

  • Page 25: Parts - Coolant System

    Parts – Coolant System Coolant System REF # PART # DESCRIPTION FCCJ0054 RADIATOR – JR ONLY FCMU0081 RADIATOR FCMU0020 CAP, 1.3 BAR FCMU0322 HOSE – USED AT CLAMP FCMU0113 RADIATOR OVERFLOW HOSE, 22” FKAM0003 KIT – HOSE – VENOM ENGINE 2025 & NEWER MCMUCL09 HOSE CLAMP –...

  • Page 26: Parts - Electrical System

    Parts – Electrical System Electrical System REF # PART # DESCRIPTION ICMU0044 COIL/CDI W/SPARK PLUG CAP ECMU0151 SPARK PLUG, AUTOLITE IRIDIUM FCMU0033 KILL SWITCH ASSEMBLY HCBC0514 M5X14mm SOCKET HEAD CAP SCREW (2 REQ’D) ICMU0023 STATOR WITH GROMMET HCBC0535 M5X35mm SOCKET HEAD CAP SCREW (2 REQ’D) HCBC0525 M5X25mm SOCKET HEAD CAP SCREW HCWF0601...

  • Page 27: Parts - Engine - Bottom End And Transmission

    Parts – Engine – Bottom End and Transmission...
  • Page 28 Engine Bottom End and Transmission REF # PART # DESCRIPTION EKMU2023 CRANKCASE SET WITH BEARINGS, SEALS & GASKET ZCMU0015 GASKET, CRANKCASE CENTER HCBC0665 M6X65mm SOCKET HEAD CAP SCREW (1 REQ’D) HCBC0604 M6X35mm SOCKET HEAD CAP SCREW (12 REQ’D) ECMU0258 CRANKSHAFT - 3 SIDE SPLINE & INTERNAL W/P ECMU0016 BEARING, CRANKSHAFT (2 REQ’D) ECMU0118...

  • Page 29: Parts - Engine Clutch And Kick Lever

    Parts – Engine Clutch and Kick Lever...
  • Page 30 Engine – Clutch and Kick Starter REF # PART # DESCRIPTION CACJ0100 CLUTCH COMPLETE ASSY - 5GX CACJ0010 3 SHOES & WASHER STACKS W BOLTS - 5GX CCMU0005 CLUTCH ARBOR – 3 SIDED SPLINE CACJ0001 WASHER STACKS - SET OF 3 - CLUTCH - 5GX HCBT0001 BOLT - TORX - 5GX CLUTCH - M6 X 29 CCMU0008...

  • Page 31: Parts - Engine - Water Pump

    Parts – Engine – Water Pump Engine – Ignition and Water Pump REF # PART # DESCRIPTION EKMU0021 WATER PUMP KIT ECMU0265 SHAFT, WATER PUMP ECKG0072 BEARING, WATER PUMP ECKG0074 SEAL, WATER PUMP SHAFT ECKG0073 IMPELLER, WATER PUMP (ALUMINUM) HCBB0512 M5X12mm BUTTON HEAD ECMU0167 BEARING –...

  • Page 32: Parts - Engine - Top End

    Parts – Engine – Top End Engine – Top End REF # PART # DESCRIPTION EKMU0361 CYLINDER KIT (INCLUDES STUDS, PISTON, RINGS, PIN & CLIPS) ZCMU0102 BASE GASKET (0.20mm) THICK ZCMU0103 BASE GASKET (0.30mm) THICK ZCMU0104 BASE GASKET (0.40mm) THICK ZCMU0105 BASE GASKET (0.50mm) THICK ZCMU0106...

  • Page 33: Parts - Exhaust System

    Parts – Exhaust System Exhaust System REF # PART # DESCRIPTION XACJ2025 EXHAUST PIPE – JR 2025 - ZCMOTE11 HEADER PIPE O-RINGS (2 REQ’D) XCMU0005 EXHAUST SPRING - SHORT XACJ0001 SILENCER MCMUGR03 MOUNTING GROMMET XCMU0051 SPACER HCBC0630 M6x 30 SHCS HCHA0003 M6 CLIP NUT XCC60020...

  • Page 34: Parts - Forks & Triple Clamps

    Parts – Forks & Triple Clamps...
  • Page 35 Front Forks and Triple Clamps REF # PART # DESCRIPTION KACJ2018 FORK ASSEMBLY JR – FORK LEGS ONLY KCMU0035FXX FORK GUARD SET – MEGA FLO YELLOW (STOCK) KCMU0035 FORK GUARD SET – BLACK (SHOWN) KCMU0035WHT FORK GUARD SET – WHITE HCSP0610 BOLT - FORK GUARD (7 REQ’D, NUMBER PLATE &...

  • Page 36: Parts - Forks - Leg Assembly - Brake Side

    Parts – Forks – Leg Assembly – Brake Side...
  • Page 37 Parts – Forks – Leg Assembly – Brake Side REF # PART # DESCRIPTION HCBC0408 4 X 8 SHCS CLEAR ZINC ZCKG0001 GASKET, BLEED SCREW FORK KCCS0004C FORK CAP - CONVENTIONAL 32MM USD ZCMUOR18 O-RING – 3mm x 27mm ID KCCS0036 FORK - SPRING WEAR PLATE 32MM KCCS0005...

  • Page 38: Parts - Forks - Leg Assembly - Non-Brake Side

    Parts – Forks – Leg Assembly – Non-Brake Side...
  • Page 39 REF # PART # DESCRIPTION HCBC0408 4 X 8 SHCS CLEAR ZINC ZCKG0001 GASKET, BLEED SCREW FORK KCCS0004S FORK CAP – SMART LEG 32MM USD ZCMUOR18 O-RING PV SOLENOID - CX65 KCCS0036 FORK - SPRING WEAR PLATE 32MM KCCS0005 FORK - OUTER TUBE 32MM KCCS0035 RING CLIP FORK OUTER WEAR RING 32MM KCCS0006...

  • Page 40: Parts - Frame - Mounting Hardware I

    Parts – Frame – Mounting Hardware I Frame – Engine, Swingarm, Tank, and Pipe Mounts REF # PART # DESCRIPTION FACJ2025 FRAME 2025 CX50JR HCBC0502 M5x 20mm SHCS HCBH0880 M8x 80mm HEX BOLT HCWF0802 8mm FLAT WASHER HCNL0801 M8 LOCK NUT TAMU0005 FOOTPEGS (PAIR) (STANDARD) FCMU0031...

  • Page 41: Parts - Front Brakes

    Parts – Front Brakes Front Brakes REF# PART # DESCRIPTION BACJ0005 BRAKE ASSY – FRONT CARD – JR/P3 BCCJ0004 HOSE – BRAKE FRONT BAMU0009 LEVER ASSEMBLY – THIN FORMLY BAMU0006 MASTER CYLINDER ASSEMBLY 11.0 CARD BAMU0020 CALIPER – FRONT – CARD 2 PISTON BKMU0009 KIT 505 ORGANIC BRAKE PADS, WITH BOLT AND CLIP BCMU0222...

  • Page 42: Parts - Front Wheel

    Parts – Front Wheel Front Wheel REF # PART # DESCRIPTION WAMUF021BLK WHEEL WITH BEARINGS SPOKE STYLE – BLACK ANODIZE WCMU0043 FRONT AXLE - HOLLOW HCSP1016M BOLT – ALUMINUM AXLE PULL WCMU0024 PLUG - BLACK PLASTIC HCBC0514 M5X14mm SOCKET HEAD CAP SCREW (5 REQ’D) BCMU0222 BRAKE ROTOR –...

  • Page 43: Parts - Plastic & Seat

    Parts – Plastic & Seat...
  • Page 44 Parts – Plastic & Seat Plastic and Seat REF # PART # DESCRIPTION TCCS0009FXX FRONT FENDER – FLO YELLOW TCCS0009x FRONT FENDER x – DENOTES COLOR BLK, WHT, YEL, FLO HCSP0610 FRONT FENDER MTG BOLTS (4 REQD) TCMU0041W FRONT NUMBER PLATE – WHITE FRONT NUMBER PLATE x –...

  • Page 45: Parts - Rear Brake

    Parts – Rear Brake...
  • Page 46 Parts – Rear Brake Rear Brake System REF # PART # DESCRIPTION BACS0002 BRAKE SYSTEM – REAR (M/C-LINE-CALIPER) BCMU0027 BRAKE PIVOT BOLT BCMU0501 SEAL – BRAKE PEDAL (2 REQ’D) BCMU0069 BRAKE PEDAL – ASSEMBLY 50cc – WITH TOE PIECE BCMU0023T TOE PIECE HCBC0501 M5X 12mm SOCKET HEAD CAP SCREW...

  • Page 47: Parts - Rear Wheel

    Parts – Rear Wheel Rear Wheel REF # PART # DESCRIPTION WAMUR021BLK REAR WHEEL W/BEARINGS – BLACK ANODIZE WCMU1075D34 TIRE - REAR - 70/100-10 - DUNLOP MX34 WCMUTU10 TUBE, 10" PCMU0001 MASTER LINK 420 PCMU0088 CHAIN 420 X 88 PCC50138 38T SPROCKET (STANDARD) PCC501xx SPROCKET xx DENOTES TEETH –...

  • Page 48: Parts - Shock

    Parts – Shock Rear Shock REF# PART # DESCRIPTION SACJ2025 SHOCK ABSORBER SCMU0043 SHOCK – BEARING SPERICAL SHOCK MOUNT – (2REQ’D) SCMU0039 O-RING – SHOCK – BUSHING (4 REQ’D) SCMU0042 SHOCK – MOUNT BUSHING (4 REQ’D) SCMU0058 SHOCK – WHITE NYLON TIP SET SCREW M6-1.0 SCMU0056 SHOCK –...

  • Page 49: Parts - Shock - Internal

    Parts – Shock - Internal Rear Shock REF# PART # DESCRIPTION SCMU0037 O-RING LOW SPEED COMP ADJUSTER SCMU0038 O-RING HIGH SPEED COMP ADJUSTER SCMU0036 O-RING COMP ADJUSTER CAP SCC60007 O-RING COMPRESSION ADJUSTER SCMU0051 O-RING – IFP SCMU0052 IFP SEAL BAND SCMU0033 O-RING SHOCK BASE SCMU0050 RESERVOIR CAP RETAINER RING SCMU0035 O-RING CHARGE CAP...

  • Page 50: Parts - Swingarm Assembly

    Parts – Swingarm Assembly Swingarm REF # PART # DESCRIPTION GAMU2025 SWINGARM – BLACK – 2025 - GCMU0001 SWINGARM BUSHING (SINGLE PIECE) (4 REQ’D) GCCS0001 SPACER - PIVOT TUBE (2REQ’D) GCMU0041 SWINGARM CHAIN GUARD - CX50 - WITH MOHAWK AND FOOT HCFH0512 M5X12mm FLAT HEAD SCREW HCWF0501...

  • Page 51: Service

    Service Trained technicians with precision gauging and proper assembly fixtures carefully assemble all Cobra engines to specific tolerances. 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.

  • Page 52: Base Gasket Selection

    Base Gasket Selection Tools required  17mm wrench  1mm flexible solder material  measurement calipers When rebuilding the ‘top end’ of your Cobra motorcycle, care must be taken to ensure the proper squish clearance. Squish clearance is defined as the minimum distance between cylinder head and piston at TDC, and there are negative effects of either having too much or too little clearance.
  • Page 53 proper torque specifications leaving off the spark plug and ignition cover (piston rings can be left off to ease of assembly).  Carefully insert the solder wire though the spark plug hole, into the cylinder far enough such that the tip of the wire touches the left or right side cylinder wall (not the front or back as the piston will rock more and give incorrect measurement).

  • Page 54: Cfd Adjustment

    CFD Adjustment This section tells you what to do if you have tested and determined that the CFD requires adjustment. Tools required  5mm & 10mm hex key  Pliers to remove the old cotter key  A new cotter key (Cobra MIL spec recommended – Hardware store ones will become brittle from the hot oil and randomly fail) ...

  • Page 55: Complete Engine Disassembly Procedure

    Procedure 1. Remove the seat. 2. Turn of the fuel at the petcock and disconnect the fuel line. 3. Remove the tank (8 mm socket). 4. Remove the carburetor from the inlet (flat head or Phillips head screwdriver, 7 mm nut driver). 5.

  • Page 56: 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 57: 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 as well as the rest of the engine.

  • Page 58: Clutch

    13. 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. Once installed slightly rotate the cylinder back and forth insuring that the rings are properly seated.
  • Page 59 engagement force. The stacks in each set of three will measure within 0.05mm (0.002”). There are many variables in an automatic centrifugal clutch. These variables are set to world class standards from the factory but will change over time as the components wear, relax, and just plain get used.

  • Page 60: Clutch Assembly

    CAUTION: You should apply heat to the arbor near the clutch bolt threads or you will very likely break the Torx bit upon attempted removal. CAUTION: It is easy to prematurely damage the clutch and other engine components with improper clutch adjustment. If you are unsure of how to adjust the clutch, contact the Cobra Technical Support Group before making adjustments.

  • Page 61: Ignition

    4. Clean the threads of the crank shaft and the clutch nut. 5. Install the clutch arbor on the crank. Making sure that the backing spacer in place on the crank. 6. Apply high strength thread locking agent to the threads and install the clutch nut and torque to 40 ft-lb (54Nm).
  • Page 62 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.

  • Page 63: Cooling System

    Cooling System Radiator fluid removal: Remove the coolant drain plug (10mm hex key) on the bottom of the engine cases. NOTE: Inspect the old coolant for evidence of oil, combustion byproducts (black ‘oil slick’ stuff) or other things that may indicate a problem.
  • Page 64 Tools recommended for impeller service:  Flat head screwdriver  2.5mm hex key  3mm hex key  4mm hex key  10mm hex key  Water Pump Installation tool - MCMUTL08B  Slide hammer with fitting to thread into threads on end of shaft (M6x1.0) ...

  • Page 65: Fuel & Air System

    CAUTION: Damage may occur if one attempts to install the water pump assembly and it’s not aligned correctly in the bore. 11. Holding the tool squarely over the water pump assembly tap it firmly into place. 12. The assembly is installed properly when the retaining screw can be tightened and it does not cause a bind on the spinning shaft (use medium strength thread lock on the retainer screw).
  • Page 66 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.

  • Page 67: Reeds

    1. Make sure the fuel is shut off and remove the carburetor 2. Remove the carburetor. 3. Drain the fuel from the carburetor. 4. Disassemble the carburetor. 5. Immerse all the metal parts in a carburetor cleaning solution. 6. After the parts are cleaned, dry them with compressed air. 7.

  • Page 68: Rear Wheel Pullers

    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. Rear wheel alignment: Either  Accurately measure the distance from the swingarm pivot to the axle center on each side or ...

  • Page 69: Front Forks

    Front Forks Tools recommended for front fork service:  Flat head screwdriver  Hammer  Pick  Seal driver MCMUTL02  9/16” (loose 14 mm) wrench  25mm wrench or socket  5 wt fork oil FORK DISASSEMBLY PROCEDURES: o Using the 25mm wrench, remove the fork cap. o Drain the fork oil into a suitable container.

  • Page 70: Rear Shock

    CAUTION: It is helpful to cover the sharp corners of the fork leg with tape or thin plastic before sliding on the new seal. Also take care that the inner lip is not folded over when installing. 4. Slide bushing (#3) onto lower fork leg. 5.
  • Page 71 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, & electronics ...

  • Page 72: Suspension

    Suspension Adjustment 1. Front forks 1.1. Fork oil 1.1.1. Oil type 1.1.1.1. Heavier weight oil – more damping – slower responding 1.1.1.2. Lighter weight oil – less damping – quicker responding 1.1.2. Oil quantity / level 1.1.2.1. Greater quantity / higher level – greater bottoming resistance, stiffer near the end of the travel.

  • Page 73: Front Fork Operation

    2.4.2. Softer (less damping, quicker) - reduces resistance to the suspension motion when the suspension is returning to full length Front Fork Operation The front suspension on the CX50SR works under the principals of hydraulic damping, and it features full adjustability to help tune the fork to meet each rider’s needs. The CARD fork contains MXT ‘Smart Leg’...

  • Page 74: Rear Shock Adjustments

    The speed at which the fork rebounds can be adjusted at the top of the conventional leg. Turning the adjustment screw clockwise slows the rate at which the fork extends after being compressed, and likewise, turning the screw counter-clockwise returns the leg to its extended position faster.
  • Page 75 Bike tends to jump ‘rear end high’ Harder High Speed Compression Bike tends to jump ‘rear end low’ Softer High Speed Compression Frequent rear end bottoming Harder Compression Damping Bottoms after end of continuous bumps Softer rebound damping 1) Harder rebound, 2) Softer Low and Rear end ‘kicks’...

  • Page 76: Proactive Suspension Adjustments

    Proactive Suspension Adjustments Once you have the suspension adjusted for decent overall feel, you can make proactive adjustments when faced with different racing conditions. Situation Actions Sand track Lower the rear end (increase race sag). Sand track Stiffer compression and rebound damping. Long fast track Lower the forks in the clamps by 3 mm.

  • Page 77: 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. Symptoms of improper jetting are listed below.
  • Page 78 o The fuel is fresh and uncontaminated o The oil and fuel have been mixed in the proper ratio o The carburetor is clean (no plugged jets) o The air filter is properly clean and oiled o The float height is within proper specification (proper measuring technique is described later in this section) NOTE: Perform all jetting changes on a motorcycle that has been warmed up to proper operating temperature.

  • Page 79: Troubleshooting

    PART THROTTLE Adjust for desired acceleration Using an area of the track that allows the rider to operate and mid throttle and transition (accelerate, or ‘roll on’) from closed, or mostly closed throttle, to a larger throttle opening. Observe the rich and lean symptoms listed above. Adjust the jet needle position by moving the clip from its current position (move the clip higher on the needle to make the bike run leaner, or move the clip lower on the needle to make the bike run richer) to one higher or lower.
  • Page 80 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 & no mods) iii) Spark plug cap off iv) Engine Shut-off ‘kill’...
  • Page 81 Change Control Who Rev Date Assy/pg Changes made...

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