Text preview for : Kymco Agility 125 R16 - Service Manual [08] [Cylinder Piston] by salvacolnome.pdf part of KYMCO Agility 125 cc Service Manual (part 8) Cylinder Piston [pag. 10]
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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
8. CYLINDER/PISTON AGILITY CITY 125
8
1.0kg-m
8
Do not bend
8-0
8. CYLINDER/PISTON AGILITY CITY 125
SERVICE INFORMATION.......................8-1 PISTON REMOVAL................................. 8-2
TROUBLESHOOTING..............................8-1 PISTON INSTALLATION........................ 8-6
CYLINDER REMOVAL ...........................8-2 CYLINDER INSTALLATION ................. 8-6
SERVICE INFORMATION
GENERAL INSTRUCTIONS
The cylinder and piston can be serviced with the engine installed in the frame.
After disassembly, clean the removed parts and dry them with compressed air before inspection.
SPECIFICATIONS
Item Standard (mm) Service Limit (mm)
I.D. 52.4 52.410 52.50
Warpage 0.05
Cylinder
Cylindricity 0.05
True roundness 0.05
Ring-to-groove Top 0.015 0.055 0.09
clearance Second 0.015 0.055 0.09
Top 0.10 0.25 0.5
Piston, Ring end gap Second 0.10 0.25 0.5
piston ring Oil side rail 0.2 0.7
Piston O.D. 52.370 52.390 52.3
Piston O.D. measuring position 9mm from bottom of skirt
. Piston-to-cylinder clearance 0.010 0.040 0.1
Piston pin hole I.D. 15.002 15.008 15.04
Piston pin O.D 14.994 15.000 14.96
Piston-to-piston pin clearance 0.002 0.014 0.02
Connecting rod small end I.D. bore 15.016 15.034 15.06
TROUBLESHOOTING
When hard starting or poor performance at low speed occurs, check the crankcase breather for
white smoke. If white smoke is found, it means that the piston rings are worn, stuck or broken.
Compression too low or uneven
compression Excessive smoke from exhaust muffler
Worn, stuck or broken piston rings Worn or damaged piston rings
Worn or damaged cylinder and piston Worn or damaged cylinder and piston
Compression too high Abnormal noisy piston
Excessive carbon build-up in combustion Worn cylinder, piston and piston rings
chamber or on piston head Worn piston pin hole and piston pin
8-1
8. CYLINDER/PISTON AGILITY CITY 125
Cylinder
CYLINDER REMOVAL
Remove the cylinder head.
Remove the cam chain guide.
Remove the cylinder base bolts.
Remove the cylinder.
Remove the cylinder gasket and dowel pins. Gasket Dowel Pins
Clean any gasket material from the cylinder
surface.
PISTON REMOVAL
Remove the piston pin clip.
Place a clean shop towel in the crankcase
to keep the piston pin clip from falling
into the crankcase.
Press the piston pin out of the piston and
remove the piston.
Piston Rings Piston
8-2
8. CYLINDER/PISTON AGILITY CITY 125
Inspect the piston, piston pin and piston rings.
Remove the piston rings.
Take care not to damage or break the
piston rings during removal.
Clean carbon deposits from the piston ring
grooves.
Install the piston rings onto the piston and
measure the piston ring-to-groove clearance.
Service Limits:
Top: 0.09mm replace if over
2nd: 0.09mm replace if over
Gap
Remove the piston rings and insert each
piston ring into the cylinder bottom.
Use the piston head to push each piston
ring into the cylinder.
Measure the piston ring end gap.
Service Limit: 0.5mm replace if over
Measure the piston pin hole I.D.
Service Limit: 15.04mm replace if over
8-3
8. CYLINDER/PISTON AGILITY CITY 125
Measure the piston pin O.D.
Service Limit: 14.996mm replace if below
Measure the piston O.D.
Take measurement at 9mm from the
bottom and 90 to the piston pin hole.
Service Limit: 52.3mm replace if below
Measure the piston-to-piston pin clearance.
Service Limit: 0.02mm replace if over
CYLINDER INSPECTION
Inspect the cylinder bore for wear or damage.
Measure the cylinder I.D. at three levels of
top, middle and bottom at 90 to the piston
pin (in both X and Y directions).
Service Limit: 52.50mm repair or replace if
over
Measure the cylinder-to-piston clearance.
Service Limit: 0.1mm repair or replace if
over
The true roundness is the difference between
the values measured in X and Y directions.
The cylindricity (difference between the
values measured at the three levels) is subject
to the maximum value calculated. Top
Service Limits: Middle
True Roundness: 0.05mm repair or replace
if over Bottom
Cylindricity: 0.05mm repair or replace if over
8-4
8. CYLINDER/PISTON AGILITY CITY 125
Inspect the top of the cylinder for warpage.
Service Limit:
0.05mm repair or replace if over
Measure the connecting rod small end I.D.
Service Limit: 15.06mm replace if over
PISTON RING INSTALLATION
Install the piston rings onto the piston.
Apply engine oil to each piston ring.
Be careful not to damage or break the
piston and piston rings.
All rings should be installed with the
markings facing up. Top
After installing the rings, they should Second
rotate freely without sticking. Side Rail
Oil Ring
Side Rail
8-5
8. CYLINDER/PISTON AGILITY CITY 125
PISTON INSTALLATION
Remove any gasket material from the
crankcase surface.
Be careful not to drop foreign matters
into the crankcase.
Install the piston, piston pin and a new piston
pin clip.
Position the piston "IN" mark on the
intake valve side.
Place a clean shop towel in the
crankcase to keep the piston pin clip
from falling into the crankcase.
Piston Pin Clip Piston Pin Piston
CYLINDER INSTALLATION
Install the dowel pins and a new cylinder
gasket on the crankcase.
Gasket
Coat the cylinder bore, piston and piston Cylinder
rings with clean engine oil.
Carefully lower the cylinder over the piston
by compressing the piston rings.
Be careful not to damage or break the
piston rings.
Stagger the ring end gaps at 120 to the
piston pin.
8-6
8. CYLINDER/PISTON AGILITY CITY 125
Loosely install the cylinder base bolts.
Cam Chain Guide
Install the cam chain guide.
Insert the tab on the cam chain guide into
the cylinder groove.
Install the cylinder head.
Tighten the cylinder base bolts.
Cylinder Base Bolt
8-7
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