KYMCO MXU400 Service Manual

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Table of Contents

Troubleshooting

Summary of Contents for KYMCO MXU400

Page 1 FOREWORD This KYMCO Service Manual contains service, maintenance, and troubleshooting information for the 2008 KYMCO MXU400 ATV. The complete manual is designed to aid service personnel in service-oriented applications. This manual is divided into sections. Each section covers a specific ATV component or system and, in addition to the standard service procedures, includes disassembling, inspecting, and assembling instructions.
Page 2 TABLE OF CONTENTS Section 1. General Information/Specifications 2. Periodic Maintenance 3. Engine/Transmission 4. Fuel/Lubrication/Cooling 5. Electrical System 6. Drive System 7. Suspension 8. Steering/Frame 9. Controls/Indicators...
Page 5: Table Of Contents
SECTION 1 - GENERAL INFORMATION/ SPECIFICATIONS TABLE OF CONTENTS General Specifications ..........1-2 Torque Specifications ..........1-2 Torque Conversions (ft-lb/N-m) ....... 1-3 Tightening Torque (General Bolts) ......1-3 Break-In Procedure ..........1-4 Gasoline - Oil - Lubricant ........1-4 Genuine Parts ............1-5 Preparation For Storage ..........
Page 6: General Specifications
2.8 L (3.0 U.S. qt) - Change Steering Post Cap Screw Gasoline (recommended) 87 Octane Regular Unleaded Tie Rod End** Steering Post Arm KYMCO Synthetic Engine Oil (recommended) BRAKE COMPONENTS Brake Disc* Differential/Rear Drive Lubricant SAE Approved 80W-90 Hypoid Brake Hose...
Page 7: Torque Conversions (Ft-Lb/N-M)
Torque Conversions ENGINE/TRANSMISSION Torque (ft-lb/N-m) Part Part Bolted To ft-lb Clutch Shoe** Crankshaft Clutch Cover/Housing Assembly Crankcase ft-lb ft-lb ft-lb ft-lb Left-Side Cover Crankcase 35.4 69.4 103.4 Crankcase Half (6 mm) Crankcase Half 13.5 36.7 70.7 104.7 Crankcase Half (8 mm) Crankcase Half 38.1 72.1...
Page 8: Break-In Procedure
Other approved 80W-90 hypoid. This lubricant meets maintenance after break-in should include all of the lubrication requirements of the KYMCO checking of all pre- scribed adjustments and ATV front differentials and rear drives.
Page 9: Genuine Parts
Remove the air filter housing cover and air filter. Start the engine and allow it to idle; then using KYMCO Engine Storage Preserver, rapidly inject the preserver into the air filter opening for a period of 10 to 20 seconds;...
Page 10 3. Check all control cables for signs of wear or 6.Check the entire brake systems (fluid level, fraying. Replace if necessary. pads, etc.), controls, lights, headlight aim; adjust replace necessary. 4. Change the engine/transmission oil and filter. 7.Tighten all nuts, bolts, cap screws, and 5.
Page 11 SECTION 2 - PERIODIC MAINTENANCE TABLE OF CONTENTS Periodic Maintenance Chart ........2-2 Periodic Maintenance..........2-3 Lubrication Points............ 2-3 Battery..............2-3 Fuses ..............2-4 Air Filter ..............2-4 Valve/Tappet Clearance (Feeler Gauge Procedure) ........2-6 Valve/Tappet Clearance (Valve Adjuster Procedure) ........2-6 Testing Engine Compression........
Page 12: Periodic Maintenance Chart
A = Adjust I = Inspect Periodic Maintenance C = Clean L = Lubricate Chart D = Drain R = Replace T = Tighten Initial Service Every Every 3 Every 6 Every Year After Break-In Every Month or Months or Months or Item or Every...
Page 13: Periodic Maintenance
The following KYMCO ATV. procedure recommended cleaning maintaining lead-acid batteries. Always read and follow NOTE: KYMCO recommends the use of new instructions provided with battery chargers and battery gaskets, lock nuts, and seals and lubricating all products. internal components...
Page 14: Fuses
A. When using an automatic battery charger, 11. Connect the battery cables (positive cable first); always follow the charger manufacturer’s then install the battery hold-down. instructions. ! CAUTION B. When using a constant-current battery charger, use the following Battery Charging Chart. Connecting cables in reverse (positive to negative and negative to positive) can cause serious damage ! CAUTION...
Page 15 4. Dry the element. 5. Put the element in a plastic bag; then pour in air filter oil and work the oil into the element. Insert the forming spring into the element with the closely wrapped end of the spring toward the open end of the element.
Page 16: Valve/Tappet Clearance (Feeler Gauge Procedure)
3. Using a feeler gauge, check each valve/tappet clearance. If clearance is not within specifications, loosen the jam nut and rotate the tappet adjuster screw until the clearance is within specifications. Tighten each jam nut securely after completing the adjustment. ! CAUTION The feeler gauge must be positioned at the same angle as the valve and valve adjuster for an accurate...
Page 17: Testing Engine Compression
Testing Engine Compression To test engine compression, use the following proce- dure. 1. Remove the high tension lead from the spark plug. 2. Using compressed air, blow any debris from around the spark plug. CF005 2. Rotate the crankshaft to the TDC position on the ! WARNING compression stroke.
Page 18: Spark Plug
Spark Plug Muffler/Spark Arrester A light brown insulator indicates that a plug is correct. At the intervals shown in the Periodic Maintenance A white or dark insulator indicates that the engine may Chart, clean the spark arrester using the following pro- need to be serviced or the carburetor may need to be cedure.
Page 19: Adjusting Throttle Cable
2. Turn the idle adjustment screw clockwise one turn past the recommended RPM setting; then turn it Adjusting Throttle counterclockwise to 1250-1350 RPM. Cable To adjust the throttle cable free-play, follow this proce- dure. 1. Slide the rubber boot away; then loosen the jam nut from the throttle cable adjuster.
Page 20 13. Remove the oil level stick; the engine oil level should be above the illustrated “L” mark but not higher than the illustrated “F” mark. ! CAUTION Do not over-fill the engine with oil. Always make sure that the oil level is above the “...
Page 21: Front Differential/Rear Drive Lubricant
CC163D KC0077A 3. Drain the oil into a drain pan by removing the AT THIS POINT drain plug from each. To check/service oil strainer, see Section 3. 4. Place the oil strainer into position beneath the crankcase and secure with the cap screws. Tighten securely.
Page 22: Tires
Tires Suspension/Shock Absorbers/Bushings TIRE SIZES The following suspension system components should The ATV is equipped with low-pressure tubeless tires be inspected periodically to ensure proper operation. of the size and type listed (see Section 1). Do not under any circumstances substitute tires of a different type or A.
Page 23: Lights
Lights Rotate the ignition switch to the lights position; the headlights and taillights should illuminate. Test the brakelights by compressing the brake lever. The brake- lights should illuminate. HEADLIGHTS NOTE: The bulb portion of a headlight is fragile. KC163A HANDLE WITH CARE. When replacing a headlight 3.
Page 24 CHECKING/ADJUSTING HEADLIGHT AIM The headlights can be adjusted vertically and horizon- tally. The geometric center of the HIGH beam light zone is to be used for vertical and horizontal aiming. 1. Position the ATV on a level floor so the headlights are approximately 6.1 m (20 ft) from an aiming surface (wall or similar aiming surface).
Page 25: Shift Lever
Shift Lever CHECKING ADJUSTMENT KC194A 3. Tighten the jam nuts securely; then shift the trans- mission to each position and verify correct adjust- ment. 4. Install the left-side engine cover and seat making sure the seat locks securely in place. KC165 With the engine stopped and the brake lever lock Frame/Welds/Racks...
Page 26 738-420A PR377C NOTE: During the bleeding procedure, watch the reservoir sight glass very closely to make sure there is always a sufficient amount of brake fluid. When the sight glass changes from dark to light, refill the reservoir before the bleeding procedure is continued.
Page 27: Burnishing Brake Pads
1. Remove a front wheel. 2. Measure the thickness of each brake pad. 3. If thickness of either brake pad is less than 1.0 mm (0.039 in.), the brake pads must be replaced. PR377B E. Install the wheel. Tighten to 40 ft-lb. 5.
Page 28 KC149A KC128 2. Slide the auxiliary brake pedal part way off the 4. Thread a cap screw from the V-belt cover into the pivot stud but do not remove; then remove the cap driven pulley fixed face and push the movable face screws from the V-belt housing and remove the open allowing the V-belt to drop down between cover.
Page 29 3. With two drops of red Loctite #271 on the threads and with the splines of the clutch shaft protruding through the movable drive face, install the nut and tighten to 147 ft-lb. KC135 KC152A KC131 2. Install the bushing over the clutch shaft; then install the movable drive face assembly on the clutch shaft.
Page 30 6. Slide the auxiliary brake pedal fully onto the pivot stud engaging the master cylinder; then secure with the flat washer and cap screw and tighten to 20 ft-lb. KC153A 2-20...
Page 31 SECTION 3 - ENGINE/TRANSMISSION TABLE OF CONTENTS Engine/Transmission ..........3-2 Specifications ............3-3 Troubleshooting ............3-4 366 Table of Contents ..........3-7...
Page 32 Oil Filter Wrench E052 NOTE: KYMCO recommends the use of new Piston Pin Puller gaskets, lock nuts, and seals and lubricating all internal components when servicing the engine/ Side Case Puller transmission.
Page 33 Specifications* VALVES AND GUIDES CYLINDER, PISTON, AND RINGS Valve Face Diameter (intake) 30.6 mm (1.20 in.) Piston Skirt/Cylinder Clearance 0.060-0.073 mm (exhaust) 27.0 mm (1.06 in.) (0.0024-0.0029 in.) Valve/Tappet Clearance (intake) 0.076-0.127 mm Piston Diameter 15 mm (0.6 in.) 80.98-81.00 mm (cold engine) (0.003-0.005 in.) from Skirt End...
Page 34 Troubleshooting Problem: Engine will not start or is hard to start (Compression too low) Condition Remedy 1. Valve clearance out of adjustment 1. Adjust clearance 2. Valve guides worn 2. Replace cylinder head 3. Valves mistimed 3. Adjust valve timing 4.
Page 35 Problem: Engine noisy (Noise seems to come from timing chain) Condition Remedy 1. Chain stretched 1. Replace chain 2. Sprockets worn 2. Replace sprockets 3. Tension adjuster malfunctioning 3. Repair - replace adjuster Problem: Engine noisy (Noise seems to come from crankshaft) Condition Remedy 1.
Page 36 Problem: Engine runs poorly at high speed Condition Remedy 1. High RPM “cut out” against RPM limiter 1. Shift into higher gear - decrease speed 2. Valve springs weak 2. Replace springs 3. Valve timing out of adjustment 3. Adjust timing 4.
Page 37 2. Remove the heat shield; then remove the gas tank (see Section 4). Table of Contents 3. Remove the oil fittings from the engine and account for two O-rings; then disconnect the oil temperature connector and cooling fan connector. Removing Engine/Transmission ......3-7 Top-Side Components..........
Page 38 6. Remove the cap screws securing the exhaust pipe to the cylinder head; then disconnect the exhaust pipe to muffler springs and remove the exhaust pipe. Account for a grafoil seal and seal ring. KC248 KC170 KC255 5. Remove the inlet air duct, air filter housing, and air silencer duct;...
Page 39: Top-Side Components
10. Lift the rear of the engine/transmission and swing to the right; then tilt the assembly sufficiently to NOTE: KYMCO recommends the use of new remove through the right-side frame opening. gaskets, lock nuts, and seals and lubricating all internal...
Page 40 MD1264 MD1245 4. Remove the cam chain tensioner pivot cap screw NOTE: Keep the mounting hardware with the cov- and washer. ers for assembly purposes. 2. Remove the valve cover cap screws. Note the rub- ber washers on the four top-side cap screws; remove the valve cover.
Page 41 6. Using an awl, rotate the C-ring in its groove until 9. Remove the four cylinder head cap screws and it is out of the cylinder head; then remove the washers. Note that the two cap screws on the right C-ring.
Page 42 C. Cylinder D. Piston NOTE: Steps 1-11 in the preceding sub-section must precede this procedure. 12. Remove the two nuts securing the right side of the cylinder to the right-side crankcase half. MD1213 15. Using Piston Pin Puller, remove the piston pin. Account for the opposite-side circlip.
Page 43: Servicing Top-Side Components
2. Place the valve cover on the Surface Plate covered with #400 grit wet-or-dry sandpaper. Using light pressure, move the valve cover in a figure eight motion. Inspect the sealing surface for any indica- tion of high spots. A high spot can be noted by a bright metallic finish.
Page 44 2. Remove the valve seal and the lower remaining 2. Acceptable diameter range (intake valve) must be spring seat. Discard the valve seal. within specifications. 3. Acceptable diameter range (exhaust valve) must be within specifications. Measuring Valve Face/Seat Width 1. Using a micrometer, measure the width of the valve face.
Page 45 Installing Valves 1. Apply grease to the inside surface of the valve seals; then place a lower spring seat and valve guide seal over each valve guide. CC131D 3. Push the valve from side to side; then from top to bottom.
Page 46 PISTON ASSEMBLY Measuring Piston-Ring End Gap (Installed) NOTE: Whenever a piston, rings, or pin are out of tolerance, they must be replaced. 1. Place each piston ring in the wear portion of the cylinder. Use the piston to position each ring Cleaning/Inspecting Piston squarely in the cylinder.
Page 47 ATV-1069 ATV-1085B 2. Install the compression rings (1 and 2) so the let- Measuring Piston Skirt/ ter(s) on the top surface of each ring faces the Cylinder Clearance dome of the piston. Rotate the rings until the ring end gaps are on directly opposite sides of the pis- ton according to the illustration.
Page 48 3. Place the cylinder head on the surface plate cov- 2. Inspect the cylinder for pitting, scoring, scuffing, ered with #400 grit wet-or-dry sandpaper. Using warpage, and corrosion. If marks are found, repair light pressure, move the cylinder head in a figure the surface using a cylinder hone (see Honing Cyl- eight motion.
Page 49 CC127D ATV-1068A 2. Wash the cylinder in parts-cleaning solvent. Measuring Camshaft Runout 3. Inspect the cylinder for pitting, scoring, scuffing, and corrosion. If marks are found, repair the sur- NOTE: If the camshaft is out of tolerance, it must face using a ball hone. be replaced.
Page 50 Inspecting Camshaft Bearing Journal 1. Inspect the bearing journal for scoring, seizure marks, or pitting. 2. If excessive scoring, seizure marks, or pitting is found, the cylinder head assembly must be replaced. Measuring Camshaft to Cylinder Head Clearance 1. Remove the adjuster screws and jam nuts. CC145D 6.
Page 51: Installing Top-Side Components
CF060A MD1343A 2. If damaged, the camshaft must be replaced. ! CAUTION Incorrect installation of the piston rings will result in engine damage. Installing Top-Side Components 1. Install the piston on the connecting rod making sure there is a circlip on each side and the open end of the circlip is directed upwards or down- wards.
Page 52 3. Lubricate the inside wall of the cylinder; then using a ring compressor or the fingers, compress the rings and slide the cylinder over the piston. Route the cam chain up through the cylinder cam chain housing; then remove the piston holder and seat the cylinder firmly on the crankcase.
Page 53 12. With the alignment pin installed in the camshaft and the cam lobes directed down (toward the pis- ton), place the camshaft in position and verify that the timing mark on the magneto is visible through the inspection plug and that the timing marks on the camshaft sprocket are parallel with the valve cover mating surface.
Page 54 A. Piston still at top-dead-center. B. Camshaft lobes directed down (toward the pis- ton). C. Camshaft alignment marks parallel to the valve cover mating surface. D. Recessed side of the sprocket directed toward the cam lobes. E. Camshaft alignment pin and sprocket alignment hole (smallest) are aligned.
Page 55: Left-Side Components
27. Install the four top-side cap screws with rubber washers; then install the remaining cap screws. Tighten only until snug. MD1146 23. Place the cam chain tensioner assembly and gasket into the cylinder making sure the ratchet side is facing toward the top of the cylinder and secure MD1261 with the two cap screws.
Page 56: Removing Left-Side Components
Removing Left-Side Components A. Cover/Stator Assembly 1. Remove the cap screws securing the outer mag- neto cover and remove the cover. 2. Remove the left-side cover-to-crankcase mounting cap screws noting the location of the 8 mm cap MD1188 screw with the washer near the middle of the left-side cover.
Page 57 6. Using Magneto Rotor Remover, break the rotor/flywheel assembly loose from the crankshaft. Remove the remover, the crankshaft protector, the rotor/flywheel, and the starter clutch gear. Account for the key. ! CAUTION Care must be taken that the remover is fully threaded onto the rotor/flywheel or damage may occur.
Page 58: Installing Left-Side Components
4. Install the cam stopper assembly. 5. Install the gear shift shaft assembly and washer making sure to align the alignment marks. MD1122 Installing Left-Side MD1239 Components 6. Install starter idler gear (No. 2) and starter idler gear (No. 1). A.
Page 59: Right-Side Components
Right-Side Components AT THIS POINT To service center crankcase components only, pro- ceed to Removing Right-Side Components. NOTE: For efficiency, it is preferable to remove and disassemble only those components which need to be addressed and to service only those KC142A components.
Page 60 MD1034 MD1068 8. Using an impact screwdriver, remove the three Phillips-head cap screws holding the air intake plate. Remove the air intake plate. MD1036 5. Remove the V-belt. MD1092 9. Remove the cap screws holding the clutch cover onto the right-side crankcase half. Note the posi- tions of the different-lengthed cap screws for installing purposes.
Page 61 11. Remove the cap screw holding the gear shift posi- tion switch onto the right-side crankcase half. MD1014 KC324A 12. Remove the gear shift position switch. Account for a spacer. MD1016 15. Remove the cam chain. KC326A 13. Remove the one-way clutch noting the direction of the green dot or the word OUTSIDE for installing purposes.
Page 62 MD1017 MD1060 18. Remove the snap ring holding the oil pump driven 21. Remove the four cap screws securing the oil gear. strainer cover; then remove the Phillips-head screws securing the oil strainer. Account for the O-ring. NOTE: Note the directional arrow for installing purposes.
Page 63: Servicing Right-Side Components
2. It is inadvisable to remove the screw securing the pump halves. If the oil pump is damaged, it must Servicing Right-Side be replaced. Components NOTE: The oil pump is a non-serviceable compo- nent and must be replaced as a complete assem- bly.
Page 64 MD1060 MD1017 4. Place the pin into position on the oil pump shaft, install the oil pump driven gear making sure the recessed side of the gear is directed inward, and secure with a new snap ring. NOTE: Always use a new snap ring when install- ing the oil pump driven gear.
Page 65 KC325A MD1117 12. Install the air intake plate. Apply red Loctite #271 to the threads of the three Phillips-head cap screws; then install and tighten securely. KC326B B. Clutch Cover C. Fixed Drive Face MD1342 D. Movable Drive Face 13. Place the driven pulley assembly into position and secure with the nut (threads coated with red Loc- NOTE: Steps 1-9 in the preceding sub-section tite #271).
Page 66: Center Crankcase Components
14. Slide the fixed drive face assembly onto the front shaft. 15. Spread the faces of the driven pulley by threading a V-belt cover cap screw into the fixed driven face and tightening until the faces open sufficiently to allow the V-belt to drop into the pulley approxi- mately 3/4 in.
Page 67: Separating Crankcase Halves
Separating Crankcase Halves 1. Remove the left-side and right-side cap screws securing the crankcase halves noting the position of the different-sized cap screws for joining pur- poses. MD1313 Disassembling Crankcase Half 1. Remove the secondary and primary driveshaft assemblies. Account for the bearing alignment C-ring on the bearing boss next to the pinion gear.
Page 68 MD1326 KC325 4. Remove the shift fork shaft and the outer shift 7. Remove the counterbalance gear. Account for the fork. key. 8. Remove the counterbalance shaft. MD1327 5. Remove snap ring and gear from the output side of MD1024 the gear cluster.
Page 69: Servicing Center Crankcase Components
10. Remove the secondary drive gear/secondary NOTE: Continue to remove, measure, and install driven gear retaining nut. From inside the crank- until backlash measurement is within tolerance. case using a rubber mallet, drive out the output Note the following chart. shaft assembly.
Page 70: Crankshaft Assembly
ATV-0104 CC290D 2. Maximum diameter must not exceed specifica- Correcting Tooth Contact tions. Measuring Connecting Rod NOTE: If tooth contact pattern is comparable to (Small End Deflection) the correct pattern illustration, no correction is necessary. 1. Place the crankshaft on a set of V-blocks and If tooth contact pattern is comparable to an incorrect mount a dial indicator and base on the surface pattern, correct tooth contact according to the follow-...
Page 71 Measuring Connecting Rod 2. Acceptable width range must be within specifica- (Big End Width) tions. COUNTERSHAFT 1. Using a calipers, measure the width of the connecting rod at the big-end bearing. ! CAUTION 2. Acceptable width range must be within specifica- When disassembling the countershaft, care must be tions.
Page 72: Assembling Crankcase Half
3. Apply a liberal amount of oil to the crankshaft bearing. Using a propane torch, heat the bearing Assembling Crankcase until the oil begins to smoke; then slide the crank- Half shaft assembly into place. NOTE: For ease of assembly, install components on the right-side crankcase half.
Page 73 9. Install the input driveshaft. KC325 7. Align the inner shift fork with the gear cluster and MD1326 with the inner washer in place, install the gear 10. Install the washer, spacer, sleeve, and reverse idler cluster and inner shift fork. While holding the gear gear.
Page 74: Joining Crankcase Halves
Joining Crankcase Halves 1. Verify that the two alignment pins are in place and that both case halves are clean and grease free. Apply Three Bond Sealant to the mating surfaces. Place the right-side half onto the left-side half. CC871 5.
Page 75 3. Align the front and rear output flanges with the 5. Connect the stator coil, trigger coil, and gear shift drive couplers; then secure with the screws and position switch connectors; then attach the engine tighten to 20 ft-lb. ground cable and starter cable and secure with cap screws and nuts.
Page 76 KC238 KC254 9. Install the shift rod onto the shift arm with bushing and flat washer and secure with an E-clip; then connect the speedometer sensor plug. KC170 7. Place the carburetor into the intake pipe being careful to align the lug on the carburetor with the alignment tabs on the air intake pipe;...
Page 77 11. If the brake pedal was removed during disassem- bling, apply grease to the brake pedal pivot stud; then install the brake pedal and secure with a flat washer and cap screw. Tighten to 20 ft-lb. KC249 KC232A KC250 KC149A 12.
Page 78 NOTES 3-48...
Page 79: Fuel/Lubrication/Cooling
SECTION 4 - FUEL/LUBRICATION/COOLING TABLE OF CONTENTS Fuel/Lubrication/Cooling ......... 4-2 Carburetor Specifications ........4-2 Carburetor Schematic ..........4-2 Carburetor ............... 4-2 Throttle Cable Free-Play ......... 4-8 Engine RPM (Idle)........... 4-8 Gas Tank ..............4-8 Oil Filter/Oil Pump ..........4-10 Testing Oil Pump Pressure........4-10 Oil Cooler ..............
Page 80: Carburetor Specifications
Fuel/Lubrication/ Carburetor Schematic Cooling NOTE: KYMCO recommends the use of new gaskets, lock nuts, and seals and lubricating all internal components when servicing engine/transmission. NOTE: Some photographs and illustrations used in this section are used for clarity purposes only and are not designed to depict actual conditions.
Page 81 4. Remove the throttle arm cover; then loosen the jam nut on the throttle cable and remove the throt- tle cable from the throttle arm. The carburetor can now be removed for service. KC257A 3. Loosen the clamp on the intake pipe and lift the carburetor up and to the rear;...
Page 82 6. Lift the float assembly from the carburetor. Account for the float valve and clip. CC748 4. Remove the Phillips-head screws securing the float chamber; then remove the chamber. Account KC0025A for the O-ring. NOTE: Note the locations of the jets, pilot screw, and holder for disassembling procedures.
Page 83 NOTE: If the slow jet is obstructed, the mixture will be extremely lean at idle and part-throttle oper- ation. 11. Inspect the float valve for wear or damage. 12. Inspect the carburetor mounting flange for damage and tightness. ASSEMBLING 1. Thread the idle adjust screw into the carburetor making sure the washer and spring are properly positioned.
Page 84 5. Place the float assembly (with float valve) into posi- tion and secure to the carburetor with the float pin. CC761A 3. Install the starter jet and slow jet. Tighten securely. KC0024 NOTE: Check float height by placing the carbure- tor on its side w/float contacting the needle;...
Page 85 KC0022A KC0019A 7. Place the U-ring into the pump housing. Position INSTALLING the spring and diaphragm assembly (lip toward the carburetor) onto the carburetor; then secure the assembly with the pump housing and three screws. 1. Connect the vent hose to the carburetor; then con- Tighten securely.
Page 86: Throttle Cable Free-Play
KC258A KC257 5. Install the gas tank (see Gas Tank in this section). Throttle Cable Free-Play To adjust throttle cable free-play, see Section 2. Engine RPM (Idle) KC266 3. Install the carburetor onto the engine making sure To adjust the idle RPM, see Section 2. the alignment lug on the carburetor is between the two tabs on the air intake pipe;...
Page 87 KC219A KC260 3. Remove the gas tank cap; then remove the gas tank cover. Place gas tank cap back on tank. KC262 CLEANING AND INSPECTING KC220 4. Remove the gas tank valve knob. NOTE: Whenever a part is worn excessively, cracked, or damaged in any way, replacement is 5.
Page 88: Oil Filter/Oil Pump
KC252A KC219A 2. Using a suitable block, support the rear of the tank 5. Install the side panels and seat making sure it locks and connect the gasline hose to the gas tank valve securely in place. Turn the gas tank valve to the outlet.
Page 89: Oil Cooler
Oil Cooler KC267 NOTE: Some oil seepage may occur when install- ing the oil pressure gauge. Wipe up oil residue 5. Machine Screw 10. Hose with a cloth. 1. Oil Cooler Assy 6. Grommet 11. Bolt 2. Oil Cooler 7. Shoulder Screw 12.
Page 90: Troubleshooting
Troubleshooting Problem: Starting impaired Condition Remedy 1. Starter jet obstructed 1. Clean jet 2. Starter jet passage obstructed 2. Clean passage 3. Carburetor leaking air 3. Replace gasket 4. Gas contaminated 4. Drain gas tank and fill with clean gas Problem: Idling or low speed impaired Condition Remedy...
Page 91: Electrical System
SECTION 5 - ELECTRICAL SYSTEM TABLE OF CONTENTS Electrical System............. 5-2 Specifications ............5-2 Battery..............5-2 RPM Limiter............. 5-2 Testing Electrical Components ........ 5-2 Accessory Receptacle/Connector ......5-2 Brakelight Switch (Pressure) ........5-3 Oil Temperature and Cooling Fan Switches .... 5-3 Fan Motor ..............
Page 92: Specifications
RPM is which show procedures for the complete servicing of approached. When the RPM limiter is activated, it the KYMCO ATV electrical system. could be misinterpreted as a high-speed misfire. NOTE: Some photographs and illustrations used in this section are used for clarity purposes only and are not designed to depict actual conditions.
Page 93: Brakelight Switch (Pressure)
4. When the brake pedal is depressed, the meter must show less than 1 ohm. Brakelight Switch NOTE: If the meter shows more than 1 ohm of (Pressure) resistance, replace the switch. The brakelight switch is located on the top of the aux- Oil Temperature and iliary brake master cylinder and is pressure activated by the hand brake or the auxiliary brake pedal.
Page 94: Fan Motor
8. Apply thread tape to the threads of the switch; then NOTE: If the meter shows more than 1 ohm of install the switch and tighten securely. resistance, troubleshoot replace switch/component, the connector, or the switch 9. Connect the switch leads. wiring harness.
Page 95: Fuses
NOTE: When testing the HI fuse holder, the head- 2. Connect the black tester lead to ground. light dimmer switch must be in the HI position; 3. The meter reading must be within specification. when testing the LIGHTS fuse holder, the headlight dimmer switch can be in either position.
Page 96: Speed Sensor
1. Set the meter selector to the DC Voltage position; 3. Install the new speed sensor into the housing with then disconnect the black/yellow and black pri- new O-ring lightly coated with multi-purpose mary wires from the coil. grease; then secure the sensor with the cap screw (threads coated with blue Loctite #242).
Page 97: Handlebar Control Switches
RESISTANCE RESISTANCE (HI Beam) ! CAUTION 1. Set the meter selector to the OHMS position. 2. Connect one tester lead to the brown/black wire; Always disconnect the battery when performing then connect the other tester lead to the lavender resistance tests to avoid damaging the multimeter. wire.
Page 98: Front Drive Selector Actuator
VOLTAGE NOTE: Resistance tests should be made with the connector disconnected and on the selector-side 1. Select the 2WD position on the front drive selector of the connector. switch; then disconnect the connector on the actu- RESISTANCE ator wiring harness. 2.
Page 99: Stator Coil
2. Select the OHMS position on the tester and con- RESISTANCE (Charging Coil) nect the red tester lead to the lavender/red wire; then move the gear shift lever to the R (reverse) CAUTION position. The meter must read less than 1 ohm. 3.
Page 100: Starter Motor
NOTE: Make sure that the ignition switch is in the NOTE: If the meter showed no voltage, inspect ON position, transmission in neutral, brake lock ground connections, starter motor lead, battery released, and the emergency stop switch in the voltage (at the battery), starter relay, or the neutral RUN position.
Page 101: Regulator/Rectifier
NOTE: Prior to replacing the CDI unit to assure the CDI unit is defective, it is advisable to perform a CDI peak voltage test (see Ignition Coil in this section) and/or perform a continuity test of the wiring har- ness from the CDI connector to the CDI unit. Regulator/Rectifier The regulator/rectifier is located under the front rack and front fenders above the oil cooler.
Page 102: Running Lights
1. Set the meter selector to the DC Voltage position. Back-Up Lights 2. Connect the black tester lead to the black wire; then connect the red tester lead to the brown/blue wire. The back-up lights connectors are located on the rear 3.
Page 103: Ignition Timing
A. If the meter shows battery voltage, troubleshoot the gear shift position switch connector or the Ignition Timing gear shift position switch. B. If the meter does not show battery voltage, inspect the LIGHTS fuse, ignition switch, or The ignition timing cannot be adjusted; however, veri- the main wiring harness.
Page 104 Problem: Magneto overcharges Condition Remedy 1. Internal battery short circuited 1. Replace battery 2. Regulator/rectifier resistor damaged - defective 2. Replace resistor 3. Regulator/rectifier poorly grounded 3. Clean - tighten ground connection Problem: Charging unstable Condition Remedy 1. Lead wire intermittently shorting 1.
Page 105 SECTION 6 - DRIVE SYSTEM TABLE OF CONTENTS Drive System ............6-2 Front Drive Actuator ..........6-2 Front Differential ............6-3 Drive Axles ............6-14 Rear Gear Case ............ 6-18 Hub................ 6-19 Hydraulic Brake Caliper......... 6-20 Troubleshooting Drive System....... 6-22 Troubleshooting Brake System......
Page 106: Drive System
E014 (capacities, lubricant type, etc.) can be found in Section 1 of this manual. NOTE: Special tools are available from the KYMCO Service Parts Department. Ring Gear Backlash 0.28-0.38 mm (0.011-0.015 in.) Ring Gear End Play 0.1-0.2 mm (0.004-0.008 in.)
Page 107: Front Differential
KC294A KC295A 4. Loosen but do not remove the mounting cap screw 4. Loosen the front cap screw; then tighten the cap at the front of the actuator; then slide the actuator screw on the driveshaft side. to the rear enough to clear the slotted mounting tab and the selector shaft.
Page 108 ATV0082A AF628D 3. Remove the front wheels. 9. Pull the steering knuckle away from the axle tak- ing care not to damage the seals as the axle clears 4. Pump up the hand brake; then engage the brake the knuckle. lever lock.
Page 109 KC291A CD106 3. Using a side-cutter (or suitable substitute), remove Disassembling Input Shaft the boot clamps; then remove the boots and splined drive from the input shaft. NOTE: This procedure can be performed on a 4. Remove the input shaft from the pinion housing. rear gear case;...
Page 110 AF983 AF993 AF984 AF994 2. Install the input shaft seal making sure it is flush with the edge of the housing. 3. Lubricate the input shaft splines with High-Perfor- mance #2 Molybdenum Disulphide Grease. NOTE: Any time drive splines are separated, clean all splines with parts-cleaning solvent and dry with compressed air;...
Page 111 1. Remove the cap screws securing the pinion hous- ing. Account for the coupler, fork, and spring. KX222 4. Install the input shaft into the housing; then install the front boot and secure with an appropriate boot KX209 clamp and the rear boot with an appropriate boot 2.
Page 112 KX178 CC875 5. Place the differential with the open side down; then lift the housing off the spider assembly. Account for shim(s) and mark as right-side. CC876 7. Using the Pinion Gear/Shaft Removal Tool and a hammer, remove the pinion gear from the gear case housing.
Page 113 NOTE: If gears are being replaced, use the exist- B. Gear Case Side - install a 1.3-1.4 mm shim and tighten the bolts to 25-31 ft-lb. Verify backlash ing shims. The numbers are scribed onto the to be within a range of 0.28-0.38 mm gears: the ring gear has the number on the oppo- (0.011-0.015 in.) and end-play to be within a site side of the gears, and the pinion gear has the...
Page 114 CC884 CC892 3. Install the pinion gear assembly into the housing. 6. Install the shift fork assembly making sure the fork Using the 48 mm Internal Hex Socket, secure the leg is facing upward. Apply a small amount of oil pinion gear assembly with the existing lock collar.
Page 115 CD110 CF267A 8. Install the proper shim onto the ring gear spider 10. Apply a liberal amount of grease to the O-ring; assembly making sure the chamfer side of the then install it on the assembled cover assembly shim is facing toward the ring gear. Install the ring making sure to seat the O-ring down around the gear in the housing;...
Page 116 CC886 CC889 3. Using a flat-nosed punch, drive the bearing out of 3. Install the pinion shaft and secure with the existing the housing. 48 mm lock collar. Tighten to 125 ft-lb. CC887 CC890 4. Place a punch on the edge of the lock collar in the Installing Needle Bearing oil gallery area;...
Page 117 CC899 CF278 2. Using a press, remove the bearing. 5. Repeat steps 1-4 for the opposite side. INSTALLING DIFFERENTIAL 1. Align the input flange with the front output flange; then place the differential into position on the frame and install the cap screws and nuts. Tighten to 38 ft-lb.
Page 118: Drive Axles
Drive Axles REMOVING REAR DRIVE AXLES 1. Secure the ATV on a support stand to elevate the wheels. ! WARNING Make sure the ATV is solidly supported on the sup- AF610D port stand to avoid injury. 2. Pump up the hand brake; then engage the brake lever lock.
Page 119 NOTE: If a boot is damaged in any way, it must be replaced with a boot kit. 3. Inspect the gear case seals for nicks or damage. DISASSEMBLING AXLES 1. Using a side-cutters (or suitable substitute), remove the large clamp from the boot. KC285 9.
Page 120 NOTE: The recess of the bearing must face 8. Apply 40 grams (1/3 of contents) of grease from the Grease Pack into the knuckles and the new out- toward the housing. side boot. CD022 ATV-1052 5. Inspect the splines of the shaft, the bearing ring, and the housing for damage.
Page 121 CD024 CD022 ! CAUTION ASSEMBLING AXLES The bearing ring must go onto the shaft with the 1. Install the inner boot with the small clamp making side without splines facing toward the small clamp sure the ends of the clamp are positioned correctly. of the inner boot or severe damage will result.
Page 122: Rear Gear Case
4. Tighten the hub hex nut (from step 2) to 200 ft-lb; then install and spread a new cotter pin making sure each side of the pin is flush to the hub nut. CD024 8. Inspect the axle components for correct position- ing of the four clamps.
Page 123: Hub
REMOVING 1. Secure the ATV on a support stand to elevate the wheel; then remove the wheel. ! WARNING Make sure the ATV is solidly supported on the sup- KC169 port stand to avoid injury. 3. Remove the two cap screws and lock nuts securing 2.
Page 124: Hydraulic Brake Caliper
3. Install the hub assembly onto the shaft. 2. Drain the brake fluid from the caliper, hose, and master cylinder. 4. Secure the hub assembly with the nut. Tighten only until snug. ! CAUTION 5. Secure the brake caliper to the knuckle with the Brake fluid is highly corrosive.
Page 125 2. Compress the caliper holder toward the caliper and install the inner brake pad; then install the outer pad. PR240A CLEANING AND INSPECTING PR238 1. Clean all caliper components (except the brake pads) with parts-cleaning solvent. 2. Inspect the brake pads for damage and excessive wear.
Page 126: Troubleshooting Drive System
Troubleshooting Drive System Problem: Power not transmitted from engine to wheels Condition Remedy 1. Rear axle shafts serration worn - broken 1. Replace shaft Problem: Power not transmitted from engine to either front wheel Condition Remedy 1. Secondary drive - driven gear teeth broken 1.
Page 127 SECTION 7 - SUSPENSION TABLE OF CONTENTS Suspension ............. 7-2 Shock Absorbers ............. 7-2 Front A-Arms ............7-2 Rear A-Arms ............7-3 Wheels and Tires ............ 7-4 Troubleshooting ............7-6...
Page 128: Suspension
Suspension Front A-Arms REMOVING NOTE: Critical torque specifications are located in Section 1. 1. Secure the ATV on a support stand to elevate the front wheels; then remove the wheels. Shock Absorbers ! WARNING Make sure the ATV is solidly supported on the sup- port stand to avoid injury.
Page 129: Rear A-Arms
5. Install the knuckle assembly onto the ball joints and secure with cap screws. Tighten to 35 ft-lb. 6. Apply grease to the hub and drive axle splines; then install the hub assembly onto the drive axle. 7. Secure the hub assembly with the nut. Tighten only until snug.
Page 130: Wheels And Tires
6. Secure the brake caliper to the knuckle with the two cap screws (right side only). Tighten the cali- per to 20 ft-lb. 7. Compress the hand brake lever and engage the brake lever lock; then secure the hub nut (from step 5) to the drive axle.
Page 131 TIRE INFLATION PRESSURE Front and rear tire inflation pressure should be 0.28 kg/cm² (4.0 psi). REMOVING 1. Secure the ATV on a support stand to elevate the wheels. ! WARNING Make sure the ATV is solidly supported on the sup- port stand to avoid injury.
Page 132: Troubleshooting
Troubleshooting Problem: Suspension too soft Condition Remedy 1. Spring(s) weak 1. Replace spring(s) 2. Shock absorber damaged 2. Replace shock absorber 3. Shock absorber preload too low 3. Adjust shock absorber preload Problem: Suspension too stiff Condition Remedy 1. A-arm-related bushings worn 1.
Page 133 SECTION 8 - STEERING/FRAME TABLE OF CONTENTS Steering/Frame............8-2 Steering Post/Tie Rods ........... 8-2 Handlebar Grip ............8-3 Steering Knuckles ........... 8-4 Measuring/Adjusting Toe-In........8-5 Front Rack ............... 8-6 Front Bumper Assembly .......... 8-6 Front Body Panel/Fender......... 8-7 Exhaust System ............8-8 Rear Body Panel/Rack ..........
Page 134: Steering/Frame
Steering/Frame NOTE: Critical torque specifications are located in Section 1. Steering Post/Tie Rods KC184A REMOVING NOTE: If tie rods are to be completely removed, 1. Remove the front body panel/fender (see Front remove the outer tie rod ends from the knuckles at Body Panel/Fender in this section).
Page 135: Handlebar Grip
7. Inspect the handlebar tube for cracks, wear, or 4. Place the handlebar and caps in place on the steer- unusual bends. ing post and with the handlebar correctly posi- tioned, tighten the cap screws to 20 ft-lb. 8. Inspect the handlebar grips for damage or wear. INSTALLING 1.
Page 136: Steering Knuckles
KC308 PR287A 3. Using a sharp utility knife, split the handlebar grip from end to end and peel off the rubber. 4. Using an adhesive solvent, clean all glue residue from the handlebar. INSTALLING 1. Apply a liberal amount of Handlebar Grip Adhe- sive to the inside of the new grip.
Page 137: Measuring/Adjusting Toe-In
PR287A KC283 2. Install the knuckle to the upper and lower ball 8. Pump the hand brake lever; then engage the brake joints and secure with the two cap screws. Tighten lever lock. to 35 ft-lb. 9. Secure the hub nut (from step 6) to the shaft. Tighten to 200 ft-lb.
Page 138: Front Rack
CLEANING AND INSPECTING 6. Using a permanent marker of some type, mark the center of each front tire (at a height parallel to the belly panel). NOTE: Whenever a part is worn excessively, cracked, or damaged in any way, replacement is necessary.
Page 139: Front Body Panel/Fender
Front Body Panel/Fender REMOVING 1. Remove the seat and both side panels. 2. Remove the front rack; then disconnect the head- light/running light connectors located on the frame. KC220 4. Remove the shift knob; then remove the shift mechanism splash shield. KC224 NOTE: Use a small screwdriver to disengage the tab connector allowing the connector assembly to...
Page 140: Exhaust System
KC210G KC224 7. Remove the front body panel/fender panel. 3. Install the screws securing the front body to the front body supports; then install the left-side and CLEANING AND INSPECTING right-side footwell fasteners. Do not tighten at this time. NOTE: Whenever a part is worn excessively, 4.
Page 141: Rear Body Panel/Rack
2. Inspect the muffler internally by shaking the muf- fler back and forth and listening for rattles or loose debris inside the muffler. NOTE: For additional details on cleaning the muf- fler/spark arrester, see Section 2. INSTALLING MUFFLER 1. Using a new grafoil seal, place the muffler into position engaging the mounting lugs into the grommets;...
Page 142 KC279 KC320A 2. Connect the light connectors and secure to the CLEANING AND INSPECTING frame; then install the battery, starter relay, and auxiliary brake. Connect all wiring making sure to NOTE: Whenever a part is worn excessively, connect the positive cables first. cracked, or damaged in any way, replacement is necessary.
Page 143: Troubleshooting
Troubleshooting Problem: Handling too heavy or stiff Condition Remedy 1. Front wheel alignment incorrect 1. Adjust alignment 2. Lubrication inadequate 2. Lubricate appropriate components 3. Tire inflation pressure low 3. Adjust pressure 4. Tie rod ends seizing 4. Replace tie rod ends 5.
Page 144 NOTES 8-12...
Page 145: Controls/Indicators
SECTION 9 - CONTROLS/INDICATORS TABLE OF CONTENTS Hand Brake Lever/Master Cylinder Assembly ..9-2 Throttle Control ............9-2 LCD Gauge ............. 9-3...
Page 146: Throttle Control
4. Inspect the banjo-fitting and bolt for cracks and deterioration and the condition of the fittings Hand Brake Lever/ (threaded and compression). Master Cylinder INSTALLING Assembly 1. Position the brake housing on the handlebar. Secure with clamp screws; then tighten securely. NOTE: The master cylinder is a non-serviceable 2.
Page 147: Lcd Gauge
LCD Gauge REPLACING To replace the LCD gauge, use the following proce- dure. 1. Remove the electric panel and disconnect the LCD gauge connector; then remove three mounting screws (two in front and one in back of gauge) and remove the gauge. AF678D INSTALLING 1.
Page 148 NOTES...

KYMCO MXU400 Service Manual

1 Section 1 - General Information/ Specifications

Section 2 - Periodic Maintenance

Table of Contents

Section 4 - Fuel/Lubrication/Cooling

Section 5 - Electrical System

Section 6 - Drive System

Section 7 - Suspension

Section 8 - Steering/Frame

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Troubleshooting

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