User Guide

ManualsBrandsKymco ManualsOtherMO MXer

7. CYLINDER HEAD/VALVES

7-0

MX’er SYSTEM

__________________________________________________________________________________

________ ________________ ________________ ________________ ________________ __________

CYLINDER HEAD/VALVES

________ ________________ ________________ ________________ ________________ __________

SERVICE INFORMATION -------------------------------------------- 7- 2

TROUBLESHOOTING ------------------------------------------------- 7- 3

CAMSHAFT REMOVAL----------------------------------------------- 7- 4

CYLINDER HEAD REMOVAL --------------------------------------- 7- 7

CYLINDER HEAD DISASSEMBLY --------------------------------- 7- 8

CYLINDER HEAD ASSEMBLY -------------------------------------- 7-10

CYLINDER HEAD INSTALLATION -------------------------------- 7-10

CAMSHAFT INSTALLATION---------------------------------------- 7-11

Summary of content (13 pages)

PAGE 1
7.
PAGE 2
7.
PAGE 3
7. CYLINDER HEAD/VALVES MX’er SYSTEM SERVICE INFORMATION GENERAL INSTRUCTIONS • The cylinder head can be serviced with the engine installed in the frame. • When assembling, apply molybdenum disulfide grease or engine oil to the valve guide movable parts, valve arm and camshaft sliding surfaces for initial lubrication. • The camshaft is lubricated by engine oil through the cylinder head engine oil passages. Clean and unclog the oil passages before assembling the cylinder head.
PAGE 4
7. CYLINDER HEAD/VALVES TORQUE VALUES Cylinder head nut Valve clearance adjusting nut Stud bolt 1.8_ 1.4_ 0.7_ SPECIAL TOOLS Valve spring compressor Tappet adjuster 2.2kgf-m 1.8kgf-m 1.1kgf-m MX’er SYSTEM Apply engine oil to threads Apply engine oil to threads E040 E012 TROUBLESHOOTING • The poor cylinder head operation can be diagnosed by a compression test or by tracing engine top-end noises.
PAGE 5
7. CYLINDER HEAD/VALVES CAMSHAFT REMOVAL Remove seat, front cover, center cover. Front fender, fuel tank and exhaust pipe. MX’er SYSTEM Cylinder Head Cover Remove the four cylinder head cover bolts to remove the cylinder head cover. Bolts Remove the cam chain tensioner cap bolt and the O-ring. Bolt Turn the cam chain tensioner screw clockwise to tighten it.
PAGE 6
7. CYLINDER HEAD/VALVES Remove the four cylinder head nuts and washers. MX’er SYSTEM Nut ＊ Diagonally loosen the cylinder head nuts in 2 or 3 times. Washer Remove the camshaft holder and dowel pins. Remove the camshaft gear from the cam chain and remove the camshaft. Camshaft Holder Camshaft Dowel Pins Cam Chain CAMSHAFT INSPECTION Check each cam lobe for wear or damage. Measure the cam lobe height. Service Limits: IN : 31.40mm replace if below EX: 31.
PAGE 7
. CYLINDER HEAD/VALVES MX’er SYSTEM Camshaft Bearings Check each camshaft bearing for play or damage. Replace the camshaft assembly with a new one if the bearings are noisy or have excessive play. CAMSHAFT HOLDER DISASSEMBLY Remove the bolt attaching the stop plate. Take out the valve rocker arm shafts using a 5mm bolt. Remove the valve rocker arms. Rocker Arm Bolt Rocker Arm Shaft CAMSHAFT HOLDER INSPECTION Inspect the camshaft holder, valve rocker arms and rocker arm shafts for wear or damage.
PAGE 8
7. CYLINDER HEAD/VALVES CYLINDER HEAD REMOVE MX’er SYSTEM Intake Manifold Remove the camshaft. Remove the carburetor. Remove the exhaust muffler. Remove the carburetor intake manifold. Bolts Remove the two cylinder head bolts. Remove the cylinder head. Cylinder Head Bolts Remove the dowel pins and cylinder head gasket. Remove the cam chain guide. Cam Chain Guide Cylinder Head Gasket Remove all gasket material from the cylinder mating surface. ＊ • Avoid damaging the cylinder mating surface.
PAGE 9
7. CYLINDER HEAD/VALVES CYLINDER HEAD DISASSEMBLY MX’er SYSTEM Valve Spring Compressor Remove the valve spring cotters, retainers, springs, spring seats and valve stem seals using a valve spring compressor. ＊• Be sure to compress the valve springs with a valve spring compressor. • Mark all disassembled parts to ensure correct reassembly. Special Valve Spring Compressor E040 Valve Spring Compressor Remove carbon deposits from the combustion chamber.
PAGE 10
7. CYLINDER HEAD/VALVES Measure each valve guide I.D. Subtract each valve stem O.D. from the corresponding guide I.D. to obtain the stemto-guide clearance. Service limits: IN : 0.06mm replace if over EX: 0.08mm replace if over ＊ If the stem-to-guide clearance exceeds the service limits, replace the cylinder head as necessary. VALVE SPRING FREE LENGTH Measure the free length of the inner and outer valve springs. Inner : 39.4mm replace if below Outer: 45.
PAGE 11
7. CYLINDER HEAD/VALVES MX’er SYSTEM CYLINDER HEAD ASSEMBLY Install the valve spring seats and valve stem seals. ＊ Be sure to install new valve stem seals. Lubricate each valve stem with engine oil and insert the valves into the valve guides. Install the valve springs and retainers. Compress the valve springs using the valve spring compressor, then install the valve cotters. Valve Spring Compressor ＊• When assembling, a valve spring compressor must be used.
PAGE 12
7. CYLINDER HEAD/VALVES MX’er SYSTEM Bolts Install two cylinder head bolts do not tighten completely. Install the cylinder head. Torque: Stud Bolts :0.8_ 1.2kgf-m Cylinder Head CAMSHAFT HOLDER ASSEMBLY Install the exhaust valve rocker arm to the “EX” mark side of the camshaft holder. Install the intake valve rocker arm and the rocker arm shafts. Tighten the bolt attaching stop plate.
PAGE 13
7. CYLINDER HEAD/VALVES Install the camshaft holder, washers and nuts on the cylinder head. Tighten the four cylinder head nuts, then tighten two cylinder head bolts compeletly. Torque: Cylinder head nut: 1.8_ 2.2kgfm MX’er SYSTEM Nut Camshaft Holder ＊• Apply engine oil to the threads of the cylinder head nuts. • Diagonally tighten the cylinder head nuts in 2_ 3 times. Washer Adjust the valve clearance. Turn the cam chain tensioner screw counterclockwise to release it.