2007 Unison Desert Cat 50 90 Youth ATV Service & Repair Manual

CONTENTS I. TECHNICAL INFORMATION……………………………………………………………. 1~4 II. TROUBLESHOOTING…………………………………………………………………….. 5~9 III. MAINTENANCE……………………………………………………………………………. 10 3-1 MAINTENANCE SCHEDULE………………………………………………………… 10 3-2 MAINTENANCE DATA………………………………………………………………... 10 3-3 FUEL LINE…………………………………………………………………………….. 11 3-4 THROTTLE OPERATION……………………………………………………………… 11 3-5 THROTTLE CABLE ADJUSTMENT………………………………………………….. 11 3-6 AIR CLEANER…………………………………………………………………………. 11 3-7 SPARK PLUG…………………………………………………………………………… 12 3-8 IDLE SPEED……………………………………………………………………………. 12 3-9 DRIVE CHAIN………………………………………………………………………….. 12 3-10 BRAKE SYSTEM……………………………………………………………………... 13 3-11 WHEELS AND TIRES………………………………………………………………… 14 3-12 STEERING SYSTEM…………………………………………………………………. 14 3-13 TOE-IN………………………………………………………………………………… 15 3-14 GEAR OIL……………………………………………………………………………... 15 IV. ENGINE SYSTEM………………………………………………………………………….. 16 4-1 ENGINE REMOVAL AND INSTALLATION…………………………………………. 16 4-2 ENGINE FUEL SYSTEM………………………………………………………………. 17~18 4-3 ENGINE LUBRICATION AND COOLING SYSTEM………………………………… 18~20 4-4 ENGINE COMBUSTION SYSTEM…………………………………………………… 20~25 4-5 TRANSMISSION SYSTEM…………………………………………………………… 25~31 4-6 CRANKSHAFT / CRANKCASE………………………………………………………. 31~35 4-7 A.C.G. GENERATOR…………………………………………………………………... 35~36 V. CARBURETOR SYSTEM………………………………………………………………….. 37 5-1 CARBURETOR REMOVAL…………………………………………………………… 37 5-2 STARTER PLUNGER INSPECTION………………………………………………….. 38 5-3 FLOAT CHAMBER DISASSEMBLY………………………………………………….. 38~39 5-4 FUEL HEIGHT INSPECTION…………………………………………………………. 39 5-5 CARBURETOR INSTALLATION……………………………………………………... 39~40 5-6 REED VALVE…………………………………………………………………………... 40 VI. FRAME SYSTEM…………………………………………………………………………... 41 6-1 FRONT WHEEL AND STEERING SYSTEM…………………………………………. 41~50 6-2 REAR WHEELS………………………………………………………………………… 50~54 6-3 FENDERS AND EXHAUST PIPE……………………………………………………... 55~57 VII. ELECTRICAL SYSTEM……………………………………………………………………. 58 7-1 TROUBLESHOOTING…………………………………………………………………. 58 7-2 BATTERY REMOVAL / INSTALLATION…………………………………………….. 59 7-3 A.C.G. INSPECTION…………………………………………………………………… 59 7-4 IGNITION COIL INSPECTION………………………………………………………... 60 7-5 START MOTOR………………………………………………………………………. 61 7-6 START RELAY INSPECTION………………………………………………………... 61

1 I.TECHNICAL INFORMATION SAFETY GASOLINE IS EXTREMELY FLAMMABLE AND IS EXPLOSIVE UNDER CERTAIN CONDITIONS. NEVER RUN THE ENGINE IN A CLOSED AREA. THE EXHAUST CONTAINS POISONOUS CABRON MONOXIXIDE THAT MAY CAUSE LOSS OF CONSCIOUSNESS AND MAY LEAD TO DEATH. AVOID CONTACT WITH THE SULPHURIC ACID INSIDE THE BATTERY. IF THE SULPHURIC ACID COMES IN CONTACT WITH ANY PART OF YOUR BODY WASH THE AREA IMMEDIATELY WITH WATER. CONTACT YOUR DOCTOR IMMEDIATELY IF THE SULPHURIC ACID GETS INTO YOUR EYES. PREFACE THE CONTENTS OF THIS MANUAL PROVIDE THE SERVICE INFORMATION FOR THE UNSION DESERT CAT 50 & 90cc. MOST CHAPTERS START WITH A SYSTEM OR ASSEMBLY ILLUSTRATION AND SPECIFICATIONS ON THE FOLLOWING PAGES GIVE DETAILED PROCEDURES. IF YOU DO NOT KNOW WHAT THE SOURCE OF TROUBLE IS, PLEASE GO TO THE TROUBLESHOOTING GUIDE FOR ADDITIONAL HELP. ALL THE CONTENTS OF THIS MANUAL ARE BASED ON THE LATEST MODEL INFORMATION UNISON RESERVES THE RIGHT TO MAKE CHANGES AT ANY TIME WITHOUT NOTICE AND WITHOUT ANY RESPONSIBILITY OR ENGAGEMENT ON OUR PART.

2 SPECIFICATION ATV TYPE DS50 DS90 ENGINE Type 2 Stroke Horizontal 2 Stroke Horizontal Displacement 49cc 82.5cc Bore and stroke 40×39.2mm 50×42mm Compression 7.2:1 6.0:1 Carburetion Mikuni – M1A Mikuni – M2A Ignition C.D.I C.D.I Starting Electric & Kicker Electric & Kicker Lubrication Separated Separated Oil tank capacity 1 liter or 1 quart 1 liter or 1 quart Transmission Automatic (C.V.T) Automatic (C.V.T) CHASSIS Overall length 57” or 1440mm 58” or 1470mm Overall width 34” or 860mm 35” or 870mm Overall high 36” or 910mm 38” or 950mm Wheelbase 39” or 980mm 39” or 980mm Dry weight 227 lbs. or 103kg 243 lbs. or 110kg Fuel tank capacity 1.3gal. or 5 liter 1.3gal. or 5 liter SUSPENSION Front Single A-Arm Single A-Arm Rear Single damper Single damper BRAKES Front Drum Drum Rear Drum / Disk Drum / Disk TIRE Front 16×8-7 19×7-8 Rear 16×8-7 19×7-8 COLORING Red/ Blue/White /Black Red/Blue/White/Black

SERIAL NUMBER Please record the frame and engine serial numbers for future reference. The frame serial number is stamped on the frame. FRAME NO. The engine serial number is stamped on the left side of the engine crankcase ENGINE NO. 3

4 TORQUE VALUES ENGINE Desert Cat 50 / 90 Cylinder head nut 10-11 Ft-Lbs or 1.3~1.5kg-m Spark plug 11-15 Ft-Lbs or 1.5~2.0 kg-m Cylinder head bolt 10-15 Ft-Lbs or 1.4~2.0 kg-m Alternator bolt 25-29 Ft-Lbs or 3.5~4.0 kg-m FRAME Desert Cat 50 / 90 Handlebar upper holder bolt 15-16 Ft-Lbs or 2.0~2.2 kg-m Steering shaft nut 33-36 Ft-Lbs or 4.5~5.0 kg-m Steering shaft bushing holder nut 15-16 Ft-Lbs or 2.0~2.2 kg-m Wheel rim bolt 25-29 Ft-Lbs or 3.5~4.0 kg-m Tie rod lock nut 22-25 Ft-Lbs or 3.0~3.5 kg-m Knuckle nut 25-29 Ft-Lbs or 3.5~4.0 kg-m Handlebar lower holder nut 33-36 Ft-Lbs or 4.5~5.0 kg-m Front wheel bolt 25-29 Ft-Lbs or 3.5~4.0 kg-m Front axle nut 29-33 Ft-Lbs or 4.0~4.5 kg-m Rear axle nut 33-36 Ft-Lbs or 4.5~5.0 kg-m Rear wheel bolt 25-29 Ft-Lbs or 3.5~4.0 kg-m Exhaust muffler mounting bolt 5-7 Ft-Lbs or 0.7~1.0 kg-m Engine hanger bolt 15-17 Ft-Lbs or 2.0~2.3 kg-m Drive sprocket 17T or 19T 33-36 Ft-Lbs or 4.5~5.0 kg-m

II.TROUBLESHOOTING ENGINE DOES NOT START POSSIBLE REASON CHECK FUEL FLOW TO CABRURETOR 5 NO FUEL IN FUEL TANK CLOGGED FLOAT VALVE CLOGGED FUEL LINE NOT OK OK SPARK TEST FAULTY SPARK PLUG FOULED SPARK PLUG FAULTY C.D.I. UNIT FAULTY ALTERNATOR FAULTY ENGINE STOP SWITCH POORLY CONNECTED, BROKEN OR SHORTED WIRES FAULTY IGNITION COIL FAULTY SPARK PLUG WIRE FAULTY PULSE GENERATOR FAULTY IGNITION SWITCH FAULTY SAFFTY SWITCH NOT OK WEAK OR NO SPARK OK TEST CYLINDER COMPRESSION WORN CYLINDER AND PISTON RINGS DAMAGED CYLINDER HEAD GASKET START THE ENGINE AUTO CHOKE OFF OR DAMAGED BUT DOESN’T START ENGINE FIRES, NOT OK OK AUTO CHOKE POWER WIRE DISCONNECTED IMPROPERLY ADJUSTED AIR SCREW IMPROPER IGNITION TIMING FUEL / AIR MIXTURE RATIO IS TOO LEAN REMOVE AND INSPECT SPARK PLUG WET PLUG CARBURETOR FLOODED IMPROPERLY ADJUSTED AIR SCREW FUEL / AIR MIXTURE RATIO TOO RICH AUTO CHOKE STUCK OR DAMAGED AIR CLEANER DIRTY

POOR PERFORMANCE AT LOW AND IDLE SPEEDS POSSIBLE REASON CHECK IGNITION TIMING 6 FAULTY C.D.I. CHECK CABRURETOR AIR SCREW ADJUSTMENT MIXTURE TOO LEAN MIXTURE TOO RICH CHECK FOR LEAKING INTAKE PIPE DETERIORATED INSULATOR O-RING LOOSE CARBURETOR PERFORM SPARK TEST WEAK OR INTERMITTENT SPARK NOT OK NOT OK NOT OK NOT OK OK OK OK LOOSE OR DISCONNECTED IGNITION SYSTEM WIRES FAULTY, CARBON OR WET FOULED SPARK PLUG FAULTY ALTERNATOR FAULTY C.D.I. UNIT FAULTY IGNITION SWITCH FAULTY IGNITION COIL FAULTY PULSE GENERATOR FAULTY SPARK PLUG WIRE FAULTY ENGINE STOP SWITCH

POOR PERFORMANCE AT LOW AND IDLE SPEEDS POSSIBLE REASON CHECK IGNITION TIMING NOT OK OK FAULTY C.D.I. UNIT FAULTY PULSE GENERATOR CHECK FUEL LINE AT CARBURETOR LACK OF FUEL IN TANK CLOGGED FUEL LINE CLOGGED FUEL VALVE FUEL FLOW RESTRICTED OK REMOVE CARBURETOR JETS CLOGGED CHECK FOR CLOG OK CLEAN WITH HIGH PRESSURE AIR GUN PERFORM SPARK TEST WEAK OR INTERMITTENT SPARK DIRTY CLEAN THE FILTER 7

POOR PERFORMANCE AT LOW AND IDLE SPEEDS POSSIBLE REASON RAISE WHEELS OFF GROUND AND SPIN BY HAND BRAKE DRAGGING DRIVE CHAIN TOO TIGHT DAMAGED WHEEL BEARING WHEEL BEARING NEEDS LUBRICATION CHECK TIRE PRESSURE 8 PUNCTURED TIRE FAULTY TIRE VALVE ACCELERATE SLOWLY FUEL/AIR MIXTURE RATIO TOO RICH OR LEAN CLOG IN AIR CLEANER CLOG IN MUFFLER RESTRICTED FUEL FLOW CHECK IGNITION TIMING FAULTY PULSE GENERATOR FAULTY C.D.I UNIT TEST CYLINDER COMPRESSION LEAKING HEAD GASKET WORN CYLINDER AND PISTON RINGS CHECK CARBURETOR CLEAN CARBURETOR CHECK SPARK PLUG CLEAN THE SPARK PLUG SPARK PLUG IS INCORRECT HEAT RANGE CHECK FOR ENGINE OVERHEATING EXCESSIVE CARBON DEPOSIT IN COMBUSTION CHAMBER WRONG TYPE OF FUEL FUEL/AIR MIXTURE RATIO IS LEAN USE OF POOR QUALITY FUEL ACCELERATE OR RUN AT HIGH SPEED WORN PISTON AND CYLINDER OK OK OK OK OK PRESSURE NORMAL SPIN FREELY OVERHEATING FOULED OR DISCOLORED CLOGGED PRESSURE LOW DOES NOT SPIN FREELY TOO LOW ENGINE SPEED INCREASES ENGINE SPEED DOES NOT INCREASE KNOCKS FUEL/AIR MIXTURE RATIO IS LEAN WRONG TYPE OF FUEL IGNITION TIMING TOO ADVANCED EXCESSIVE CARBON DEPOSIT IN COMBUSTION CHAMBER

2007 Unison Desert Cat 50 90 Youth ATV Service & Repair Manual

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