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Related Manuals for Cobra Moto CX50 JR
Summary of Contents for Cobra Moto CX50 JR
- Page 2 For parts orders contact your local dealer To locate your closest Cobra dealer log on to www.cobramotorcycle.com or call (517) 437-9100 If you need technical assistance contact your local dealer or call the Cobra Technical Support Hotline at (517) 437-9100 Cobra Motorcycle MFG., Inc.
- 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. “WARNING” THE COBRA CX50JR IS A COMPETITION MODEL ONLY AND IS NOT MANUFACTURED FOR, NOR SHOULD IT BE USED ON PUBLIC STREETS, ROADS OR HIGHWAYS.
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Page 4: Table Of Contents
Table Of Contents General Information ....................5 Specifications - General ..................5 Optional Components..................6 Specifications - Torque Values................7 Break-In Procedure ...................8 Starting Procedure ....................9 Maintenance .......................10 Tips .........................10 Schedule ......................11 Replacing Transmission / Clutch Lubricant .............12 Proper Chain adjustment.................14 Air Filter Cleaning....................14 Fork Oil Replacement..................16 Frictional Drive (CFD)..................17 Parts ........................18... - Page 5 Parts – Front Wheel ..................34 Parts – Plastic & Seat..................35 Parts – Rear Brake..................36 Parts – Rear Wheel ..................37 Parts – Shock ....................38 Parts – Swingarm Assembly................39 Service........................40 Engine Service ....................40 Base Gasket Selection ................41 Engine Removal ..................43 Complete Engine Disassembly Procedure ..........44 Top End Disassembly Procedure ..............44 Splitting the Cases..................45 Engine assembly ..................46...
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Page 6: General Information
General Information Specifications - General Items CX50 JR Dimensions Wheelbase 35.75” (908mm) Wheel size 10” (254mm) Seat height 23.9” (607 mm) Engine Type 2-stroke, single cylinder, reed valve Cooling system Liquid-cooled Coolant 50/50 antifreeze-coolant / distilled water Displacement 49.8 cc Bore and stroke 39 mm x 41.7 mm, “V”... -
Page 7: Optional Components
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 Optional Components Call your dealer, or the factory, for details... -
Page 8: Specifications - Torque Values
Specifications - Torque Values Torque Value Size & Fastener Remarks ft-lb in-lb Cylinder head nuts M6 X 1.0 Crankcase bolts M6 x 1.0 Spark plug (SP) (SP) (SP) M14 x 1.25 Stator bolts M5 X 0.8 Stator cover bolts M4 X 0.75 Clutch cover bolts M6 X 1.0 Clutch nut... -
Page 9: Break-In Procedure
Your Cobra CX50 JR 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 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
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. -
Page 11: Maintenance
CAUTION: Never rev an engine full throttle when it's cold or slightly warmed up. Also, for best clutch performance, warm up the bike before taking off. This is a high performance race motorcycle. Too much application of throttle will likely land your little racer on his or her arse. Fenders can be replaced but bruised egos and other body parts take longer. -
Page 12: Schedule
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, CMxxxx7xxx is a 2007 MY CX50 JR. Schedule • Between each ride Check the air filter (clean and re-oil as necessary). -
Page 13: Replacing Transmission / Clutch Lubricant
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. Use ER70S6 filler if welding on the frame. - Page 14 Figure 1 4. After it has drained, reinstall the plug, being sure that the gasket is in place. 5. Reapply oil from oil fill plug 235 cc (8.0 oz) Cobra Venom 3 Shoe Clutch Milk thru the oil fill plug. NOTE: Putting additional oil, up to 350 ml (12 oz), can help clutch life.
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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. For proper adjustment, the chain should have 35 mm (1 3/8”) free movement just behind the chain block with no load on the bike (figure 2) - Page 16 screwdriver 3. Pull the filter / boot assembly back, up, and out the top of the airbox. 4. Clean the filter in a nonflammable solvent to remove the filter oil. Do not clean the air filter with gasoline or other highly volatile petroleum product. Diesel fuel or kerosene would be preferred but caution should still be taken.
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Page 17: Fork Oil Replacement
Fork Oil Replacement Tools required • 5 & 6 mm Allen wrench • 19 mm wrench or socket (two required) • Spring clip remover Disassembly 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. -
Page 18: Frictional Drive (Cfd)
Frictional Drive (CFD) The Cobra Frictional Drive (CFD) is essentially a slip clutch that dissipates torque spikes transmitted from the rear wheel to the rest of the drive line and engine. Instead of these torque spikes potentially damaging internal components, the CFD allows the transmission to slip with respect to the engine. -
Page 19: Parts
Parts Parts – Airbox and Inlet System Figure 7 Airbox and Inlet System REF # PART # DESCRIPTION ZCMU0132 GASKET – REED TO CYLINDER ECKG0202 REED BLOCK ASSEMBLY Not Shown ECKG0205 REEDS REPLACEMENT 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) FCMU0019 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
Parts - Carburetor Carburetor REF. # PART # DESCRIPTION RCCM0001 COMPLETE CARBURETOR 14MM RCMU0305 CARB SLIDE Figure 9 RCMU0601 NEEDLE RCMU00 ATOMIZER AU2.62 RCMU00xx MAIN JET, xx denotes size RCMU00xx PILOT JET, xx denotes size CHOKE JET RCMU0301 FLOAT RCMU0102 RUBBER CABLE CAP SEAL RCMU0003 CABLE ADJUSTOR... -
Page 22: Parts - Coolant System
Parts – Coolant System Coolant System REF # PART # DESCRIPTION FCCJ0004 RADIATOR WITH CAP MCMUHO02 RADIATOR HOSE LEFT MCMUCL07 HOSE CLAMP EACJ0001 MOUNTING BRACKET – RADIATOR BOTTOM HCBC0607 M6X50 SOCKET HEAD CAP SCREW HCNL0601 6MM LOCK NUT MCKGGR00 GROMMET – RADIATOR MOUNTING MCCMHO01 RADIATOR HOSE RIGHT TCCJ0001... -
Page 23: Parts - Electrical System
Parts – Electrical System Electrical System REF # PART # DESCRIPTION IAMU0005 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) ICMU0018... -
Page 24: Parts - Engine - Bottom End And Transmission
Parts – Engine – Bottom End and Transmission Figure 7A Engine Bottom End and Transmission REF # PART # DESCRIPTION EKMU0023 ENGINE CASE SET W/B&S 50 07 EKMU0023 ENGINE CASE SET W/B&S 50 07 ZCMU0601 GASKET, CRANKCASE CENTER HCBC0605 6X40MM SOCKET HEAD CAP SCREW (6 REQ’D) HCBC0608 6X55MM SOCKET HEAD CAP SCREW (1 REQ’D) HCBC0606... -
Page 25: Parts - Engine Clutch And Kicker
Parts – Engine Clutch Kicker Figure 7B Engine – Clutch and Kick Starter REF # PART # DESCRIPTION CAMU0005 CLUTCH COMPLETE CAMU0013 CLUTCH SHOES (SET OF 3) WITH BOLT & WASHERS CCMU0029 CLUTCH ARBOR CAMU0010 SPRINGS, WASHER & BOLT (SET OF 3) HCBS0004 CLUTCH BOLT (3 REQ’D) ECMU0018... -
Page 26: Parts - Engine - Water Pump
Parts – Engine – Water Pump Figure 7C Engine – Ignition and Water Pump REF # PART # DESCRIPTION EKMU0001 WATER PUMP KIT ECKG0142 SHAFT, WATER PUMP ECKG0072 BEARING, WATER PUMP ECKG0074 SEAL, WATER PUMP SHAFT ECKG0073 IMPELLER, WATER PUMP (ALUMINUM) ECKG0004 RETAINER, WATER PUMP ASSEMBLY (MAY NOT BE NEEDED) HCBC1512... -
Page 27: Parts - Engine - Top End
Parts – Engine – Top End Figure 7D Engine – Top End REF # PART # DESCRIPTION ECMU0129 CYLINDER (INCLUDES PISTON, RINGS, PIN & CLIPS) BASE GASKET 0.015” (0.4mm thick) For other Base Gaskets refer to ZCKG0501 Base Gasket Selection section of this manual ECMU0060x PISTON KIT (“x”... -
Page 28: Parts - Exhaust System
Parts – Exhaust System Figure 8 Exhaust System REF # PART # DESCRIPTION XCCJ2009 2008 CX50 SR EXHAUST PIPE ZCMOTE11 HEADER PIPE O-RINGS (2 REQ’D) XCMU0005 EXHAUST SPRING - SHORT PIPE GROMMET MALE (ONLY AVAILABLE IN MCMUGR02 MCMUGR02 GROMMET KIT) MCMUGR10 PIPE GROMMET FEMALE PIPE GROMMET SPACER (ONLY AVAILABLE IN MCMUGR02... -
Page 29: Parts - Forks & Triple Clamps
Parts – Forks & Triple Clamps Figure 9 Front Forks and Triple Clamp REF # PART # DESCRIPTION ******** KACM2007 FORK ASSEMBLY WITH TRIPLE CLAMPS OUTER FORK LEG – RIGHT (NON BRAKE) SIDE KCMZ0029 (NOT AVAILABLE) OUTER FORK LEG ASSY – RT W/ SEAL & SWIPER KCMZ0131 (NOT AVAILABLE) NOT SHOWN... -
Page 30: Parts - Forks - Leg Assembly
Parts – Forks – Assembly Figure 10 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 11 Frame – Engine, Tank, and Pipe Mounts, Brake Snake REF # PART # DESCRIPTION FAMU0004 FRAME 2007 CX50 JR HCBH1403 SWINGARM BOLT HCNL1402 SWINGARM LOCK NUT (M14X1) HCBH0880 M8X80 SOCKET HEAD CAP SCREW... -
Page 32: Parts - Frame - Mounting Hardware Ii
Parts – Frame – Mounting Hardware II Figure 12 Frame – Seat, Fender, Right Side Panel, Brake Pedal, Silencer & Shock Mounts REF # PART # DESCRIPTION FAMU0004 FRAME 2007CX50 JR 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 13 Frame – Radiator, Footpeg, Chain Roller, and Airbox Mounts REF # PART # DESCRIPTION FAMU0004 FRAME 2007 CX50 JR 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 14 Front Brakes REF # PART # DESCRIPTION BAKG0003 FRONT BRAKE ASSEMBLY BCKG0030 HOSE – BRAKE FRONT BCKG0023 ALLOY BRAKE LEVER BCKG0024 BRAKE PERCH & MASTER CYLINDER ASSY W/ LEVER BCKG0029 CALIPER – FRONT BKKG0001 BRAKE PADS, WITH “E”... -
Page 35: Parts - Front Wheel
Parts – Front Wheel Figure 15 Front Wheel REF # PART # DESCRIPTION WACJ0001 WHEEL WITH BEARINGS (NO TIRE & TUBE) ’08 SPOKE STYLE WCMU1050B FRONT TIRE 10X2.50” BRIDGESTONE WCMU1050D FRONT TIRE 10X2.50” DUNLOP WCMU1050V FRONT TIRE 10X2.50” VEE RUBER WCMUTU10 TUBE 10”... -
Page 36: Parts - Plastic & Seat
Parts – Plastic & Seat Plastic and Seat REF # PART # DESCRIPTION NOT SHOWN TCCJ2008 GRAPHIC KIT 2008 CM 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 17 Rear Brake System REF # PART # DESCRIPTION BCCM0002 BRAKE PEDAL W/ TEETH BCMU0008 CABLE – BRAKE SNAKE BCMU0009 CRIMP – BRAKE SNAKE (2 REQ’D) HCBB0803 M8X40 BUTTON HEAD SCREW HCNL0801 8MM LOCK NUT HCBH0602 M6X25 HEX HEAD BOLT (BRAKE STOP ADJUST) HCNS0601... -
Page 38: Parts - Rear Wheel
Parts – Rear Wheel Figure 18 Rear Wheel REF # PART # DESCRIPTION WACM2007R WHEEL W / BEARINGS, ’08 SPOKE STYLE WCMU1075B TIRE – REAR 10X2.75” BRIDGESTONE WCMU1075D TIRE – REAR 10X2.75” DUNLOP WCMU1075V TIRE – REAR 10X2.75” VEE RUBBER WCMUTU10 TUBE –... -
Page 39: Parts - Shock
Parts – Shock Figure 19 REAR SHOCK REF# PART # DESCRIPTION SACM2007 SHOCK ABSORBER SCMUOH05 SPRING – STANDARD (285 lb/in) SCMUOH04 SPRING – LIGHT (275 lb/in) SCMUOH06 SPRING – HEAVY (295 lb/in) HCBF1040 M10X40 FLANGE HEAD BOLT... -
Page 40: Parts - Swingarm Assembly
Parts – Swingarm Assembly Figure 20 Swingarm REF # PART # DESCRIPTION GAMU0004 SWINGARM GCMU0001 SWINGARM BUSHING (SINGLE PIECE) GCMU0009 SPACER - PIVOT TUBE GCMU0017 CHAIN GUARD HCFH0516 M5X16 FLAT HEAD SCREW HCWF0501 5MM FLAT WASHER HCNL0501 5MM LOCK NUT HCBF0620 M6X20 FLANGE HEAD BOLT (2 REQ’D) PAKG0001... -
Page 41: 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 42: Base Gasket Selection
Shut off the fuel petcock. Install the compression gauge into the spark plug hole. 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. Base Gasket Selection Tools required •... - Page 43 Code Supplied Base Cobra # Gasket Thickness inch Part # 0.008 ZCMU0702 0.25 0.010 ZCMU0011 0.012 ZCMU0703 0.015 ZCKG0501 0.020 ZCMU0705 0.024 ZCMU0706 0.028 ZCMU0707 0.031 ZCMU0708 0.035 ZCMU0015 0.039 ZCMU0016 NOTE Tolerances will affect the actual gasket thicknesses. If during the course of the maintenance more parts than the base gasket are changed, the squish clearance should be measured, and possibly a different base gasket will be required.
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Page 44: Engine Removal
Upon completion, your final assembly squish clearance should agree with the chart below Engine Removal To service the bottom end and transmission, the engine must be removed from the frame. Tools required • 10, 11, 13, 22 mm wrench • 8, 10, 14, 17 &... -
Page 45: Complete Engine Disassembly Procedure
NOTE: Only drive the swingarm bolt far enough to clear the engine, leave it holding the one side of the swingarm to the frame Remove the engine from the right side of the frame. NOTE: If you are merely performing a top end service skip ahead to Top End Disassembly Procedure. -
Page 46: 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 47: Engine Assembly
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 48 9. Torque to 12 Nm (105 in-lb) in the pattern shown in figure 28. 10. Trim away any excess gasket material if necessary. NOTE: Check engine mount holes for excess material that may cause problems in engine installation. 11. Install the piston with new wrist pin bearing and, pin and clips. CAUTION: Be sure to install 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...
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Page 49: Clutch
23. 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 24. Install the CFD. 25. -
Page 50: Clutch Washer Stackups
4. If necessary apply heat to the center clutch hub. CAUTION: Do not heat the crankshaft threads or the aluminum shoes. 5. Keep tension on the puller as you are heating it. 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. -
Page 51: Clutch Adjustment Washers
Figure 32 Some configuration of clutch spring stack. Each ‘spring’ stack contains multiple springs (Belleville washers) - arranged into three, four, or five ‘flying saucers’, or turned away against the flat washer(s). Shown is the 4 ½ stack.. Stack Total Flying Saucers Turned Away Std. - Page 52 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.
- Page 53 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 32) 2. Clean the threads of the stack bolt and the clutch with contact cleaner removing all old thread locking material.
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Page 54: Ignition
kick lever to ½ stroke and hold while tightening the six screws completely with the other hand. 8. Fill with 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. Following is a list of things that will make your engine run hot. - Page 55 • 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. 2. Insert the dial indicator into the spark plug hole. 3. Remove the four bolts from the ignition cover. 4.
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Page 56: Cooling System
Cooling System Radiator fluid removal: Remove the coolant drain plug (13mm bolt) on the front 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. Tools recommended for impeller service: •... - Page 57 6. Thread a slide hammer onto the end of the water pump shaft and remove the assembly. NOTE: It is quite common for the older plastic impellers to fall off the end of the shaft during this step of the process if that is the case, then follow the steps at the end of this section to remove the seal and impeller.
- Page 58 10. Hold the installation tool firmly against the engine case and tap on the end of the water pump shaft with a dead blow hammer until the insertion punch is needed 11. Continue driving the assembly with the punch until the head is flush. NOTE: The insertion punch is 0.010”...
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Page 59: Fuel & Air System
Fuel & Air System Carburetor: Tools recommended for carburetor service: • Small flat head screwdriver • WD-40 • 8mm socket 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. - Page 60 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.
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Page 61: Exhaust
location of rectangular slide indexing pin and vent elbows. 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. •... -
Page 62: Wheels & Tires
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. Wheels & Tires Rear wheel pullers Disassembly: 1. Remove axle, back wheel assembly. 2. - Page 63 1.1.2.2. Smaller quantity / lower level – less bottoming resistance, less stiff near the end of the travel. 1.2. Fork spring (optional spring) 1.2.1. Stiffer spring (higher spring rate) – stiffer throughout the travel. 1.2.2. Less stiff spring (lower spring rate) – less stiff throughout the travel. 1.3.
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Page 64: Rear Shock
Rear end ‘kicks’ over square edge bumps 1) Harder rebound, 2) Softer Compression 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). -
Page 65: Gearing
NOTE: Fork oil level affects bottoming harshness, and oil viscosity affects valving speed. 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 •... - Page 66 Rear Front Sprocket 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...
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Page 67: 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 68 NOTE: • Before making any carburetor jetting changes verify that: o You are using the proper fuel and oil 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)
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Page 69: 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 70 4) Engine cuts out at high RPMs 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...
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Page 71: Index
Index Air Filter Maintenance ....14 Forks Airbox Parts ..........28 Parts.......... 18 Frame Parts ........30 Bars and Controls ......19 Frictional Drive ......17 Base Gasket Selection....41 Front Brake Break-In .......... 8 Parts ..........33 Carburetor Front Forks Parts.......... 20 Service........63 Service ........ - Page 72 Optional Components ..... 6 Rear Wheel Parts Parts ..........37 Airbox and Filter ......18 Pullers........61 Bars and Controls...... 19 Reeds..........60 Bottom End & Transmission ..23 Shock ..........63 Carburetor ......... 20 Parts ..........38 Clutch & Kick Starter ....24 Service........68 Coolant System ......
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