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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.  
 
THE  USE  OF  THIS  BIKE  SHOULD  BE  LIMITED  TO  PARTICIPATION  IN 
SANCTIONED  COMPETITION  EVENTS  UPON  A  CLOSED  COURSE  BY  A 
SUFFICIENTLY  SKILLED  RIDER  AND  SHOULD  NOT  BE  USED  FOR  GENERAL 
OFF-ROAD RECREATIONAL RIDING.   
 
IMPROPER USE OF THIS MOTORCYCLE CAN CAUSE INJURY OR DEATH. 
 
THIS  BIKE  IS  INTENDED  FOR  EXPERIENCED  RACERS  ONLY  AND  NOT  FOR 
BEGINNERS. 
 
IT  IS  YOUR  RESPONSIBILITY  AS  THE  OWNER  OF  THIS  COBRA  MOTORCYCLE 
OR AS THE PARENT, OR LEGAL GUARDIAN OF THE OPERATOR, TO KEEP THIS 
COBRA MOTORCYCLE IN PROPER OPERATING CONDITION. 
 
THIS BIKE WAS DESIGNED FOR RIDERS THAT WEIGH LESS THAN 80 LBS WITH 
FULL RIDING GEAR AND SHOULD NOT BE OPERATED BY RIDERS THAT WEIGH 
MORE. 
 
BE  SURE  THAT  THE  RIDER  ALWAYS  WEARS  ADEQUATE  SAFETY  GEAR 
EVERYTIME HE OR SHE RIDES THEIR COBRA MOTORCYCLE. 
 

 

IMPORTANT SAFETY NOTICE 

 

Failure to follow WARNING instructions could result in severe injury or death to 
the machine operator, a bystander, or a person inspecting or repairing the 
machine. 
 
CAUTION: 
A CAUTION indicates special precautions that must be taken to avoid damage to 
the machine. 
 

NOTE:  

A NOTE provides key information to make procedures easier or clearer. 

MCCJ2015.0 

Summary of Contents for CX50 JR 2015

Page 1: ...NDED 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...

Page 2: ...ing 15 Fork Oil Replacement 15 Cobra Frictional Drive V3 CFD 16 Parts 18 Parts Airbox and Inlet System 18 Parts Bars and Controls 19 Parts Carburetor 20 Parts Coolant System 21 Parts Electrical System...

Page 3: ...rocedure 47 Top End Disassembly Procedure 48 Splitting the Cases 49 Engine Assembly 49 Clutch 51 CLUTCH ASSEMBLY 55 Ignition 56 Cooling System 57 Radiator fluid removal 57 Fuel Air System 60 Carbureto...

Page 4: ...r 49 8 cc 39 mm x 41 7 mm Electronic analogic advance Autolite XS61 4261 0 023 0 025 0 58 0 64 mm 0 040 1 0 mm Before Top Dead Center BTDC High octane pump gasoline Bel Ray H1 R Premix oil ratio after...

Page 5: ...cover bolts 5 8 70 7 9 M6 X 1 0 Clutch nut 40 480 54 10 x 1 25 Clutch bolts 12 144 16 M6 x 1 0 Engine mount bolts 22 265 30 M8 X 1 25 Swingarm pivot 21 250 28 M14 X 2 0 Shock bolt 35 420 47 M10 x 1 5...

Page 6: ...nute Allow bike to cool Ride for 15 minutes maximum avoid prolonged high RPM operation and avoid abusing the clutch with throttle blipping Allow bike to cool and inspect bike for loose fasteners Avoid...

Page 7: ...el upright position with the rear wheel off the ground 2 Pull up the choke knob and turn it to lock it 3 Kick start the engine 4 Rev the engine in short spurts turning the throttle no more than 1 4 op...

Page 8: ...leaving pistons rings and heads extremely clean with minimal pipe spooge 2 Filling your transmission with more than 8 0 oz 235 cc of lubricant will help to transfer heat from the clutch Filling with m...

Page 9: ...tch is engaging properly DO NOT feel the need to take the clutch apart to measure the spring stack clean the stack replace the springs etc Cobra has worked very hard to make a clutch that is low maint...

Page 10: ...y then reinstall the oil drain plug 4 Remove the oil fill plug and add 8 0oz of Cobra Venom 3 Shoe Clutch Milk thru the oil fill plug NOTE Putting additional oil up to 350 ml 12 oz can help clutch lif...

Page 11: ...d tighten the chain by rotating the adjustor bolts clockwise CW or loosen the chain by rotating the adjustor bolts CCW 5 Retighten the axel bolt to 25 ft lb 34 Nm 6 Retighten the adjustor bolt Rear Br...

Page 12: ...is installed such that one must push forward toward the front of the bike to remove Otherwise the clip is apt to come undone while riding To adjust see figure 2b 1 Loosen the lock nut 10mm 2 Undo the...

Page 13: ...engage the brake lever pedal and hold it there as if engaging the brakes While doing this pull on the plunger of the syringe Doing this will cause a vacuum in the system The vacuum will swell the air...

Page 14: ...aken Hot soapy water works well 5 Clean the filter in hot soapy water to remove all dirt particles 6 Allow it to dry thoroughly 7 Saturate with filter oil and remove excess NOTE The Cobra is equipped...

Page 15: ...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 B...

Page 16: ...tment screw pin into the damper rod 4 Install the fork spring and spring pad 5 Extend the damper rod completely and Compress the fork spring enough to begin threading the fork cap back onto the damper...

Page 17: ...ly up against the sprocket 4 Verify with a torque wrench applied to the Sprocket Socket that the V3 CFD does not slip below 81 Nm 60 ft lb in either direction 5 If there is slippage below 81 Nm 60 ft...

Page 18: ...D CAP SCREW 6 MCKGHO04 HOSE CLAMP CARBURETOR TO MANIFOLD 7 RCCM0001 CARBURETOR 14mm 8 RCCM1301 VELOCITY STACK 9 MCKGHO01 HOSE CLAMP AIR BOOT TO CARBURETOR 10 RCCJ0004 AIR FILTER WITH BOOT 11 RCMU0405...

Page 19: ...FCMU0019 THROTTLE CABLE 7 BAKG0003 BRAKE ASSEMBLY FRONT 8 FCMU0033 KILL SWITCH ASSEMBLY 9 HCBC0803 M8X30mm SOCKET HEAD CAP SCREW 4 REQ D 10 HCBC0825 M8X25mm SOCKET HEAD CAP SCREW 4 REQ D 11 TKMU0404 B...

Page 20: ...EW 12 RCMU0106 CARB TOP 13 ZCMU0007 TOP CARB GASKET 14 RCMU0004 SLIDE SPRING 15 RCMU0028 NEEDLE RETAINER PLATE 16 RCMU0007 NEEDLE CLIP 17 RCMU0204 CHOKE ASSEMBLY NOT SHOWN RCMU0209 O RING CHOKE ASSEMB...

Page 21: ...AP SCREW 6 HCNL0601 M6 LOCK NUT 7 MCKGGR00 GROMMET RADIATOR MOUNTING 8 MCCMHO01 RADIATOR HOSE RIGHT 9 TCCJ0001 BUMPER RAD BRACKET 10 FCMU0049 OVERFLOW HOSE 20 11 MCMUCL05 HOSE CLAMP OVERFLOW HOSE 12 E...

Page 22: ...SHER SPECIAL 2 REQ D 7 HCNL0501 M5 LOCKNUT 2 REQ D 8 ICMU0018 STATOR WITH GROMMET 9 HCBC0535 M5X35mm SOCKET HEAD CAP SCREW 2 REQ D 10 HCBC0525 M5X25mm SOCKET HEAD CAP SCREW 11 HCWF0504 WASHER FOR STAT...

Page 23: ...SION WITH GEAR 12 ECMU0100 SECONDARY SHAFT TRANSMISSION WITH GEAR 13 ECMU0001 BEARING TRANMISSION SECONDARY SHAFT 14 ECKG0031 BEARING OUTPUT SHAFT RIGHT SIDE 15 HCBH0612 M6X12mm HEX HEAD SCREW BEARING...

Page 24: ...24 Parts Engine Clutch and Kick Lever...

Page 25: ...FD 7mm 16 ECMU0301 GEAR V3 CFD 17 ECMU0308 BELLEVILLE SPRING V3 CFD 18 ECMU0307 NUT V3 CFD 19 HCCP0002 COTTER PIN 3 32 X 1 20 EAMU0001 KICKSTART GEAR SHAFT 21 ECMU0116 SPRING KICKSTART 22 ZCMUB014 O R...

Page 26: ...SHAFT 5 ECKG0073 IMPELLER WATER PUMP ALUMINUM 6 HCBC1512 M5X12mm SOCKET HEAD CAP SCREW STAINLESS 7 ECMU0167 BEARING WATER PUMP BIG 8 ECKG0175 WATER PUMP PULLEY FAN TYPE DRIVEN 9 ECMU0180 BELT RETAINER...

Page 27: ...NGS PIPE TO FLANGE 2 REQ D 5 ECMU0155 PISTON RINGS 2 PER SET 6 ECMUSR00 SNAP RING FOR PISTON 2 PER SET 7 ECKG0012 WRIST PIN 8 ECMU0077 BEARING WRIST PIN 9 ZCMUOR07 O RING EXHAUST FLANGE 10 ECMU0086 EX...

Page 28: ...E O RINGS 2 REQ D 3 XCMU0005 EXHAUST SPRING SHORT 4 MCMUGR02 GROMMET KIT 5 XCMU0028 PIPE SILENCER SEAL 6 XCMU0032 SILENCER 7 MCMUGR03 MOUNTING GROMMET 2 REQ D 8 TCKG0001 SPACER 2 REQ D 9 HCWF1478 SILE...

Page 29: ...AMP TOP JR 10 HCNJ0102 JAM NUT STEERING STEM 2 REQ D 11 HCBC0806 M8X30mm SOCKET HEAD CAP SCREW 4 REQ D 12 HCBC0820 M8X20mm SOCKET HEAD CAP SCREW 4 REQ D 13 TKMU0404 HANDLE BAR CLAMP KIT SHORT STANDARD...

Page 30: ...30 Parts Forks Leg Assembly Brake Side...

Page 31: ...K 0 25 KG MM 32mm 15 HCNJ3824 NUT JAM 3 8 24 CLASS 8 16 KCC60068 RING CLIP FORK SPRING GUIDE RETAINER 17 KAC60003 DAMPER ROD ASSEMBLY 18 KCC60058 O RING MID VALVE ADJ NEEDLE 19 KCC60050 FORK MID VALVE...

Page 32: ...32 Parts Forks Leg Assembly Non Brake Side...

Page 33: ...KCCj3218 LIGHT SPRING FORK 0 18 KG MM 32mm 15 KCCJ3225 HEAVY SPRING FORK 0 25 KG MM 32mm 15 HCNJ3824 NUT JAM 3 8 24 CLASS 8 16 KCC60068 RING CLIP FORK SPRING GUIDE RETAINER 17 KAC60003 DAMPER ROD ASS...

Page 34: ...6X85mm SOCKET HEAD CAP SCREW 12 HCBB0635 M6X35mm BUTTON HEAD CAP SCREW 13 HCBF0620 M6X20mm FLANGE HEAD BOLT 14 HCNF0602 M6 NYLOC FLANGE NUT 15 HCBF0625 M6X25mm FLANGE HEAD BOLT 16 MCMUGR03 GROMMET SIL...

Page 35: ...HCBC0608 M6X55mm SOCKET HEAD CAP SCREW 5 HCNL0601 M6 LOCK NUT 6 MCKGGR00 GROMMET RADIATOR MOUNT 2 REQ D ON BOTTOM 2 ON TOP BRACKET 7 ECHA0109 MOUNTING BRACKET RADIATOR TOP 2 REQ D 8 HCBC0665 M6X65mm...

Page 36: ...AD CAP SCREW ACCESSORY MCMUBF01 BRAKE FLUID DOT 5 1 OR HIGHER ACCESSORY BCKG0031 BLEED KIT MULTIPLE SYRINGES FITTINGS HOSE ACCESSORY BCKG0028 LEVER ADJUSTMENT KIT ACCESSORY BCKG0027 RESERVOIR SEAL KIT...

Page 37: ...CBC0501 M5X12mm SOCKET HEAD CAP SCREW 6 REQ D 4 BCMU0503 BRAKE ROTOR FRONT 5 WCMU0101 WHEEL SPACER LEFT SHORT 6 WCMU0120 BEARING WHEEL 2 REQ D 7 WCCJ0004 SPACER WHEEL FRONT 8 WCCJ0003 WHEEL SPACER RIG...

Page 38: ...TCHA0004 BUSHING REAR TANK MOUNTING 6 TCHA0002 CAP FUEL TANK 7 TCHA0003 HOSE FUEL CAP 8 TCMU0151 FUEL PETCOCK 9 TCCM0007 SEAT 9A TCCM0007C SEAT COVER REPLACEMENT 9B HCBB0640 M6X40mm SHCS SEAT HOLDING...

Page 39: ...LAMP 2 REQ D for hose with clear cover 13B HCCC0006 BRAKE HOSE CLAMP 2 REQ D for hose with black cover 14 HCPP0832 BRAKE HOSE CLAMP FASTENER 2 REQ D 15 BCMU0502 BRAKE ROTOR 16 HCBC0601 M6X16mm SOCKET...

Page 40: ...HCBH0702 M7X30mm HEX HEAD BOLT 4 REQ D 7A HCWF0701 7mm FLAT WASHER 4 REQ D 7B HCNL0701 M7 LOCKNUT 4 REQ D 8 WCMU0016 REAR AXLE 10 WCMU0101 WHEEL SPACER 11 WCMU0120 WHEEL BEARING SPROCKET SIDE 12 WCMU...

Page 41: ...K MOUNT BUSHING 4 REQ D 5 SCMU0058 SHOCK WHITE NYLON TIP SET SCREW M6 1 0 6 SCMU0056 SHOCK SLEEVE BLACK 7 SCMU0100 BUMPER TAPPERED SHOCK 8 SCMU0040 SHOCK SPRING PAD 9 SCMU0054 SHOCK SPRING PERCH 10 SC...

Page 42: ...CMU0051 O RING IFP 6 SCMU0052 IFP SEAL BAND 7 SCMU0033 O RING SHOCK BASE 8 SCMU0050 RESERVOIR CAP RETAINER RING 9 SCMU0035 O RING CHARGE CAP 10 HCBB0506 M5 X 6mm LONG BUTTON HEAD STAINLESS STEEL 11 SC...

Page 43: ...LAT HEAD BOLT 2 REQ D 12 HCNL0601 M6 LOCKNUT 2 REQ D 13 FAMU0005 WHEEL PULL ASSEMBLY BLOCK CAP BOLT AND WASHER 14 FCMU0203 WHEEL PULL 15 FCMU0202 WHEEL PULL ENDCAP 16 HCWF0801 8mm FLAT WASHER HCWL0801...

Page 44: ...metry of the spark plug used in this Cobra Motorcycle the adapter used with your compression tester must have a similar volume protruding into the combustion chamber to establish an accurate value Len...

Page 45: ...taken to ensure the proper squish clearance Squish clearance is defined as the minimum distance between cylinder head and piston at TDC There are negative effects of either having too much or too litt...

Page 46: ...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...

Page 47: ...coolant and disconnect the coolant lines connected to the engine 8 mm socket NOTE If the coolant looks to be free of contaminates it may be reused 7 Remove the master link from the chain 8 Remove fro...

Page 48: ...or abrasions deposits and missing coating 1 If abrasions scrapes scratches pitting etcX are found replace the cylinder 2 If deposits are all are found a Clean with muriatic acid b Once the deposits ar...

Page 49: ...Check the small needle bearings for fatigue If the bearings are damaged the engine cases should be checked to make sure the needle bearing casing didn t oblong the bearing hole in the case Needle bear...

Page 50: ...ly 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...

Page 51: ...though The sleeve bolts of the 5GX provide a low uniform stress minimal heat transfer and allow channels for flushing the clutch fibers out of the washer stacks allowing a long time between part repla...

Page 52: ...the crank 5 One at a time tighten each of the 1 4 turn until the clutch pops off Figure 30 Figure 31 Clutch puller installation CAUTION Do not use a jaw type puller CAUTION It is possible to cause dam...

Page 53: ...mer to achieve different clutch engagements hits by changing washer counts and configurations CAUTION Generally reassemble the springs as you removed them from the engine or as you received them from...

Page 54: ...e stock washer with the proper combination of adjustment washers that delivers the desired clutch hit CAUTION It is easy to prematurely damage the clutch and other engine components with improper clut...

Page 55: ...removing all old thread locking material 3 Assemble the stacks and shoes on the arbor using high strength thread lock material to the stack bolt and tighten to 16 Nm 12 ft lb 144 in lb CAUTION Avoid a...

Page 56: ...tator is not large enough There should be even clearance as the rotor rotates relative to the stator Non resistor spark plug caps should be used Resistor caps will result in a weaker spark that will r...

Page 57: ...e three 5mm bolts to adjust the stator ROTOR INSTALLATION 1 Torque the nut on the rotor to 30 ft lb 45 Nm with medium strength blue thread locking agent 2 Recheck the timing following the procedure of...

Page 58: ...rain engine coolant as described above NOTE If the impeller is damaged or broken completely back flush the coolant system to ensure no solid pieces are in the system 2 Remove ignition cover using a 4m...

Page 59: ...he tool does not sit flat against the cases the orientation of the tool to the engine is not correct Make sure that the top alignment pin is in the 2nd unthreaded hole the bottom alignment pin is also...

Page 60: ...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 impo...

Page 61: ...r brass screw that is towards the front of the engine is a fuel mixture screw This screw will also richen and lean your engine more on the bottom and mid range In warmer conditions turn the screw in I...

Page 62: ...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 Exh...

Page 63: ...and ensuring full braking performance is achieved before the lever touches the handlebar If this is not the case pump the lever several times until the lever feels firm Always make sure the rotor and...

Page 64: ...Pry the dust seal swiper from its position with a small screw driver o Using a pick remove the wire retaining ring holding the fork seals into place o Pop the fork seal out by forcibly pulling on both...

Page 65: ...mm wrench to 35 ft lb with green thread locking agent 12 Fill with 3 6 oz 107 ml 2 5 wt fork oil should measure 6 mm 0 25 above the damper cartridge tube with spring removed This oil volume works out...

Page 66: ...thickness difficult to measure accurately can only be approximated by the size of the step where it sticks out of the basket h Basket has worn and is too large There is a relationship between observe...

Page 67: ...to remember If your clutch is hitting fine don t mess with it Some things to remember to aid clutch life Change oil each ride Gear to the low side Avoid mud if possible Cut mud practice to 1 lap or n...

Page 68: ...When should the springs be replaced When the clutch hit occurs too early or too late Q Should the clutch springs be replaced if the shoes wiggle on the arbor A Not if the clutch is hitting correctly D...

Page 69: ...ture failure of engine seals bearings electronics High clutch wear It may be helpful to set up the clutch to hit early for smooth power deliv Condition Gear Taller Mud Sand Hills Hard Pack Throttle Bl...

Page 70: ...esistance to the suspension motion when the suspension is compressing 1 6 Rebound damping 1 6 1 Harder more damping slower adds resistance to the suspension motion when the suspension is returning to...

Page 71: ...il it travels into the progressive speed sensitive portion of the smart leg The speed sensitive compression component is adjustable at the top of the fork The combination of the Smart Leg and the conv...

Page 72: ...ar end low Softer rebound damping Frequent rear end bottoming Harder compression damping Bottoms after end of continuous bumps Softer rebound damping Rear end kicks over square edge bumps 1 Harder reb...

Page 73: ...der has difficulties touching the ground Shock preload Loosen the set screw and turn the spring perch in full turn increments to get the desired sag settings NOTE Always leave the spring perch rotated...

Page 74: ...rk plug when removed for inspection NOTE When inspecting the spark plug to evaluate jetting a properly jetted machine will produce a spark plug that is dry and light tan in color Environmental and alt...

Page 75: ...carburetor It is the larger of the two screws on the side of the carburetor and is unique with its knurled head for easy fingertip adjustment To raise the idle turn the screw in clockwise in 1 4 turn...

Page 76: ...n 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 Rin...

Page 77: ...tator winding damaged d Exhaust is plugged 6 Overheating a Bad stator b Water pump pulleys or belt broken c Water pump impeller broken or bolt out d Jetting too lean e Too much throttle blipping f Too...

Page 78: ...ing System 57 Engine Specifications 4 Exhaust 62 Parts 28 Fork Adjustments 71 Operation 71 Fork oil replacement 15 16 Forks Parts 29 Frame Parts 34 Frictional Drive 16 Front Brake Parts 36 Front Wheel...

Page 79: ...Seat Parts 38 Pullers 63 Rear Brake Adjustment 11 Parts 39 Rear Wheel Parts 40 Pullers 63 Reeds 62 Shock Adjustments 72 Parts 41 42 Slip Clutch 16 Spark Plug Recommended 4 Specifications 4 torque valu...

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