Text preview for : Kymco Agility 125 R16 - Service Manual [07] [Cylinder Head] by salvacolnome.pdf part of KYMCO Agility 125 cc Service Manual (part 7) Cylinder Head/Valves [pag. 13]
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AGILITY CITY 125
PREFACE
TABLE OF CONTENTS
This Service Manual describes the GENERAL INFORMATION 1
technical features and servicing
procedures for the KYMCO AGILITY FRAME COVERS/EXHAUST MUFFLER 2
CITY 125 INSPECTION/ADJUSTMENT 3
LUBRICATION SYSTEM 4
Section 1 contains the precautions for all
operations stated in this manual. Read FUEL SYSTEM 5
ENGINE
them carefully before starting any ENGINE REMOVAL/INSTALLATION 6
operation.
CYLINDER HEAD/VALVES 7
Section 2 is the removal/installation CYLINDER/PISTON 8
procedures for the frame covers which DRIVE AND DRIVEN PULLEYS/KICK
are subject to higher removal/installation STARTER 9
frequency during maintenance and FINAL REDUCTION 10
servicing operations.
CRANKCASE/CRANKSHAFT 11
CHASSIS
Section 3 describes the inspection/ FRONT WHEEL/FRONT BRAKE/ 12
adjustment procedures, safety rules and FRONT SUSPENSION
service information for each part, starting REAR WHEEL /REAR BRAKE /REAR 13
from periodic maintenance. SUSPENSION
BATTERY/CHARGING SYSTEM/A.C. 14
EQUIPMENT
ELECTRICAL
GENERATOR
Sections 6 through 17 give instructions
for disassembly, assembly and inspection IGNITION SYSTEM 15
of engine, chassis frame and electrical STARTING SYSTEM 16
equipment.
LIGHTS/INSTRUMENTS/SWITCHES 17
Most sections start with an assembly or EXHAUST EMISSION CONTROL
18
system illustration and troubleshooting SYSTEM
for the section. The subsequent pages
give detailed procedures for the section.
Our company reserves the right to make
any alteration in the design The
information and contents included in
this manual may be different from the
motorcycle in case specifications are
changed.
KWANG YANG MOTOR CO., LTD.
OVERSEAS SALES DEPARTMENT
OVERSEAS SERVICE SECTION
7. CYLINDER HEAD/VALVES AGILITY CITY 125
SERVICE INFORMATION...................... 7-1 CYLINDER HEAD DISASSEMBLY.......7-7
TROUBLESHOOTING ............................ 7-2 CYLINDER HEAD ASSEMBLY .............7-8
CAMSHAFT REMOVAL......................... 7-3 CYLINDER HEAD INSTALLATION .....7-8
CYLINDER HEAD REMOVAL .............. 7-5 CAMSHAFT INSTALLATION................7-9
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.
After disassembly, clean the removed parts and dry them with compressed air before inspection.
After removal, mark and arrange the removed parts in order. When assembling, install them in
the reverse order of removal.
SPECIFICATIONS
Item Standard (mm) Service Limit (mm)
IN 0.12
Valve clearance (cold)
EX 0.12
Cylinder head compression pressure 13kg/cm²
Cylinder head warpage
IN 29.803 29.40
Camshaft cam height
EX 29.5637 29.16
Valve rocker arm I.D. IN 10.000 10.015 10.10
EX 10.000 10.015 10.10
Valve rocker arm shaft IN 9.972 9.987 9.91
O.D. EX 9.972 9.987 9.91
Valve seat width IN 1.0 1.8
EX 1.0 1.8
Valve stem O.D. IN 4.975 4.990 4.90
EX 4.955 4.970 4.90
Valve guide I.D. IN 5.000 5.012 5.03
EX 5.000 5.012 5.03
Valve stem-to-guide IN 0.010 0.037 0.08
clearance EX 0.030 0.057 0.10
7-1
7. CYLINDER HEAD/VALVES AGILITY CITY 125
TORQUE VALUES
Cylinder head nut 2.0kg-m Apply engine oil to threads
Valve clearance adjusting nut 0.9kg-m Apply engine oil to threads
Stud bolt 0.9~1.1kg-m
SPECIAL TOOLS
Valve spring compressor
TROUBLESHOOTING
The poor cylinder head operation can be diagnosed by a compression test or by tracing engine
top-end noises.
Poor performance at idle speed White smoke from exhaust muffler
Compression too low Worn valve stem or valve guide
Damaged valve stem seal
Compression too low
Incorrect valve clearance adjustment Abnormal noise
Burned or bend valves Incorrect valve clearance adjustment
Incorrect valve timing Sticking valve or broken valve spring
Broken valve spring Damaged or worn camshaft
Poor valve and seat contact Worn cam chain guide
Leaking cylinder head gasket Worn camshaft and rocker arm
Warped or cracked cylinder head
Poorly installed spark plug
Compression too high
Excessive carbon build-up in combustion
chamber
7-2
7. CYLINDER HEAD/VALVES AGILITY CITY 125
Cylinder Head Cover
CAMSHAFT REMOVAL
Remove the center cover.
Remove the four cylinder head cover bolts
to remove the cylinder head cover.
Remove the two nuts attaching the
secondary air inlet tube.
Remove the cam chain tensioner cap screw O-ring
and the O-ring.
Screw
Turn the cam chain tensioner screw
clockwise to tighten it.
Tensioner Screw
Turn the flywheel counterclockwise so that Camshaft Gear
the "T" mark on the flywheel aligns with
the index mark on the crankcase to bring the
round hole on the camshaft gear facing up
to the top dead center on the compression
stroke.
Round Hole Punch Marks
7-3
7. CYLINDER HEAD/VALVES AGILITY CITY 125
Nut Bolt
Remove the two cylinder head bolts.
Remove the four cylinder head nuts and
washers.
Diagonally loosen the cylinder head nuts
in 2 or 3 times.
Washer
Camshaft Holder
Remove the camshaft holder and dowel
pins.
Camshaft Dowel Pins
Remove the camshaft gear from the cam
chain and remove the camshaft.
Cam Chain Camshaft Gear
CAMSHAFT INSPECTION
Check each cam lobe for wear or damage.
Measure the cam lobe height.
Service Limits:
IN : 29.40mm replace if below
EX: 29.16mm replace if below
7-4
7. CYLINDER HEAD/VALVES AGILITY CITY 125
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
Take out the valve rocker arm shafts using a
5mm bolt.
Remove the valve rocker arms.
Rocker Arm Rocker Arm Shaft 5mm Bolt
Camshaft Holder
CAMSHAFT HOLDER INSPECTION
Inspect the camshaft holder, valve rocker
arms and rocker arm shafts for wear or
damage.
If the valve rocker arm contact surface is
worn, check each cam lobe for wear or
damage.
Rocker Arm Shafts
Measure the I.D. of each valve rocker arm.
Service Limits:
IN: 10.10mm replace if over
EX: 10.10mm replace if over
Measure each rocker arm shaft O.D.
Service Limits:
IN: 9.91mm replace if over
EX: 9.91mm replace if over
7-5
7. CYLINDER HEAD/VALVES AGILITY CITY 125
Intake Manifold
CYLINDER HEAD REMOVE
Remove the camshaft.
Remove the carburetor.
Remove the exhaust muffler.
Remove the carburetor intake manifold.
Remove the cooling fan cover.
Remove the engine cover bolts and screws.
Separate the engine cover joint claws.
Remove the cylinder head. Cylinder Head
Bolts
Remove the dowel pins and cylinder head Dowel Pins Cylinder Head Gasket
gasket.
Remove the cam chain guide.
Cam Chain Guide
Remove all gasket material from the
cylinder mating surface.
Avoid damaging the cylinder mating
surface.
Be careful not to drop any gasket
material into the engine.
7-6
7. CYLINDER HEAD/VALVES AGILITY CITY 125
Valve Spring Compressor
CYLINDER HEAD DISASSEMBLY
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
Remove carbon deposits from the combustion
chamber.
Clean off any gasket material from the
cylinder head mating surface.
Be careful not to damage the cylinder
head mating surface.
INSPECTION
CYLINDER HEAD
Check the spark plug hole and valve areas for
cracks.
Check the cylinder head for warpage with a
straight edge and feeler gauge.
Service Limit: 0.05mm repair or replace if
over
VALVE SPRING FREE LENGTH
Measure the free length of the inner and outer
valve springs.
Service Limits:
Inner : 32.3mm replace if below
Outer : 35.0mm replace if below
7-7
7. CYLINDER HEAD/VALVES AGILITY CITY 125
VALVE /VALVE GUIDE
Inspect each valve for bending, burning,
scratches or abnormal stem wear.
Check valve movement in the guide.
Measure each valve stem O.D.
Service Limits:
IN : 4.90mm replace if below
EX: 4.90mm replace if below
Measure each valve guide I.D.
Service Limits: IN : 5.03mm replace if over
EX: 5.03mm replace if over
Subtract each valve stem O.D. from the
corresponding guide I.D. to obtain the stem-
to-guide clearance.
Service Limits: IN : 0.08mm replace if over
EX: 0.10mm replace if over
If the stem-to-guide clearance exceeds
the service limits, replace the cylinder
head as necessary.
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 Valve Spring Compressor
cotters.
When assembling, a valve spring
compressor must be used.
Install the cotters with the pointed ends
facing down from the upper side of the
cylinder head.
Special
Valve Spring Compressor
7-8
7. CYLINDER HEAD/VALVES AGILITY CITY 125
Tap the valve stems gently with a plastic
hammer for 2 3 times to firmly seat the
cotters.
Be careful not to damage the valves.
Dowel Pins Gasket
CYLINDER HEAD INSTALLATION
Tighten the four stud bolts.
Install the dowel pins and a new cylinder
head gasket.
Install the cam chain guide.
Torque: Stud Bolts :0.7 1.1kg-m
Stud Bolts Cam Chain Guide
Install the cylinder head.
Cylinder Head
CAMSHAFT HOLDER ASSEMBLY
Install the exhaust valve rocker arm to the Camshaft Holder
"EX" mark side of the camshaft holder.
Install the intake valve rocker arm and the
rocker arm shafts.
Align the cutout on the front end of the
intake valve rocker arm shaft with the
bolt of the camshaft holder.
Align the cross cutout on the exhaust
valve rocker arm shaft with the bolt of
the camshaft holder.
Valve Rocker Arm
7-9
7. CYLINDER HEAD/VALVES AGILITY CITY 125
Cam Chain Camshaft Gear
CAMSHAFT INSTALLATION
Turn the flywheel so that the "T" mark on the
flywheel aligns with the index mark on the
crankcase.
Keep the round hole on the camshaft gear
facing up and align the punch marks on the
camshaft gear with the cylinder head surface
(Position the intake and exhaust cam lobes
down.) and install the camshaft onto the
cylinder head.
Install the cam chain over the camshaft gear.
Round Hole Punch Marks
Dowel Pins
Install the dowel pins.
Install the camshaft holder, washers and nuts Camshaft Holder Nut
on the cylinder head.
Tighten the four cylinder head nuts and two
bolts.
Torque: Cylinder head nut: 2.0kg-m
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 counter-
clockwise to release it.
Tensioner Screw
7-10
7. CYLINDER HEAD/VALVES AGILITY CITY 125
Apply engine oil to a new O-ring and install
it.
Tighten the cam chain tensioner cap screw.
Be sure to install the O-ring into the
groove properly.
O-ring
Install a new cylinder head cover O-ring and
install the cylinder head cover.
Install and tighten the cylinder head cover
bolts.
Be sure to install the O-ring into the
groove properly.
Cylinder Head Cover
7-11
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