Stihl ms 192t User manual

STIH)
STIHL MS 192 T
2005-02

1MS 192 T
q
© ANDREAS STIHL AG & Co. KG, 2005
Contents
1. Introduction 3
2. Safety Precautions 4
3. Specifications 5
3.1 Engine 5
3.2 Fuel System 5
3.3 Ignition System 5
3.4 Chain Lubrication 5
3.5 Tightening Torques 6
4. Troubleshooting 8
4.1 Clutch 8
4.2 Chain Drive,
Chain Brake, Chain
Tensioner 9
4.3 Chain Lubrication 10
4.4 Rewind Starter 11
4.5 Ignition System 12
4.6 Carburetor 13
4.7 Engine 15
5. Chain/ Spiked
Bumper 16
5.1 Chain and Chain
Guide 16
5.2 Tensioning the Chain 17
5.3 Chain Catcher 17
5.4 Bumper Spike 17
5.5 Bumper Strips 18
6. Clutch 18
6.1 Sprocket /
Clutch Drum 20
7. Checking Operation
of Chain Brake 21
7.1 Removing and
Installing 21
7.2 Chain Tensioner 25
7.3 Bar Mounting Stud 26
8. Engine 27
8.1 Muffler / Spark
Arresting Screen 27
8.2 Leakage test 27
8.2.1 Preparations 28
8.2.2 Vacuum test 28
8.2.3 Pressure test 29
8.3 Oil Seals 30
8.4 Engine 31
8.4.1 Removal 31
8.4.2 Installation 32
8.5 Crankshaft 34
8.5.1 Removal 34
8.5.2 Installation 35
8.5.3 Crankshaft / Bearing 37
8.6 Piston 39
8.6.1 Removal 39
8.6.2 Installation 39
8.7 Piston rings 41
9. Ignition System 42
9.1 Ignition Module 42
9.1.1 Removing and
installing 42
9.2 Ignition Timing 44
9.3 Testing the Ignition
Module 44
9.4 Ignition Lead /
Spark Plug Boot 45
9.5 Flywheel 46
9.6 Short Circuit Wire 47
9.6.1 Testing 47
9.6.2 Removing and
installing 48
9.7 Troubleshooting,
Ignition System 50
10. Rewind starter 53
10.1 General 53
10.2 Removing and
Installing 53
10.3 Pawls 54
10.4 Rope Rotor 54
10.5 Starter Rope / Grip 55
10.6 Tensioning the Rewind
Spring 57
10.7 Replacing the Rewind
Spring 58
10.8 Starter Rope Guide
Bushing 59
11. Repairing the
AV System 60
11.1 Annular Buffer 60
11.2 Front Handle / Spring 61
11.3 AV Spring between
Handle Housing /
Engine Housing 62
11.4 Clamp 62
11.5 Loop 63
12. Actuating Levers 63
12.1 Throttle Trigger /
Interlock Lever /
Throttle Rod 63
12.2 Double Lever 64
12.3 Switch Shaft 65
12.4 Handle Housing 66
13. Chain Lubrication 68
13.1 Pick-up Body 68
13.2 Oil Suction Hose 68
13.3 Oil Pump 69
13.4 Valve 70
13.5 Oil Tank Filler Cap 71

2MS 192 T
Contents
14. Fuel System 72
14.1 Air Filter 72
14.1.1 Air Filter Base 73
14.2 Carburetor, Removing
and Installing 73
14.2.1 Leakage Test 74
14.3 Carburetor Repair 75
14.3.1 Metering Diaphragm 75
14.3.2 Inlet Needle 76
14.3.3 Fixed Jet 77
14.3.4 Pump Diaphragm 77
14.3.5 Choke Shaft / Choke
Shutter 78
14.3.6 Throttle Shaft /
Throttle Shutter 80
14.3.7 Accelerator Pump 81
14.3.8 Adjusting screws 82
14.4 Carburetor
Adjustment 83
14.4.1 Basic Setting 83
14.4.2 User Setting 84
14.5 Intake Elbow,
Removing and
Installing 85
14.5.1 Impulse Hose 87
14.6 Tank Vent 88
14.6.1 Testing 88
14.6.2 Removing and
Installing 89
14.7 Fuel Intake 89
14.7.1 Pick-up Body 89
14.8 Fuel Hoses 90
14.8.1 Fuel Pump 92
14.8.2 Fuel Tank Filler Cap 93
14.8.3 Tank Housing,
Removing and
Installing 93
15. Special Servicing
Tools 94
16. Servicing Aids 96

3MS 192 T
This service manual contains
detailed descriptions of all the
typical repair and servicing
procedures for this power tool.
Refer to the illustrated spare parts
lists during all repair work. These
lists show the installation position
and order in which the individual
parts and modules should be
assembled.
Refer to the latest edition of the
relevant parts list to check the part
numbers of any replacement parts
required.
A fault on the machine may be due
to several causes. To help locate
the fault, consult the chapter on
"Troubleshooting" and the
"STIHL Service Training System"
for all function groups.
Refer to the "Technical Information"
bulletins for engineering changes
which have been introduced since
publication of this service manual.
Technical information bulletins also
supplement the parts list and
service manual until an updated
edition is issued.
The special tools mentioned in the
descriptionsarelistedinthechapter
"Special Servicing Tools" of this
manual. Use the part numbers to
identify the tools in the STIHL
Special Tools manual.
It lists all the special servicing tools
currently available from STIHL.
Symbolsareincludedinthetextand
pictures for greater clarity.
The meanings are as follows:
In the text:
:= Action to be taken
as shown in the illustration
above the text
– = Action to be taken
but not shown in the illustration
above the text
In the illustrations:
AItem pointer (short)
aDirection of movement (long
arrow)
b4.2 = Reference to another
chapter,i.e.tochapter4.2in
this case.
Service manuals and technical
information bulletins are intended
exclusively for the use of properly
equipped repair shops. They must
not be passed on to third parties.
Servicing and repairs are made
considerably easier if the machine
is mounted on assembly stand (3)
5910 890 3100. For this purpose,
securetheclamp(2)5910890 2000
to the assembly stand with two
screws (1). Engage the adjusting
screw and stud in the outer holes of
217RA000 TG
12
3
1
the clamp and secure the chainsaw
with the nut (arrow).
The sprocket cover and bar and
chainmustberemovedfirst;pullthe
hand guard back against the front
handle for this purpose.
Always use original STIHL
replacement parts.
They can be identified by the STIHL
part number
STIH) logo
and the
STIHL parts symbol (
The symbol may appear alone on
small parts.
1. Introduction

4MS 192 T
Specific national safety regulations
and the safety instructions in the
instruction manual must be
observed if the machine has to be
started up during maintenance or
repair work.
Petrolishighlyinflammableandcan
also be explosive under certain
conditions.
Improper handling may result in
burns and other serious injuries.
Donotbring anyfire,flame, sparkor
other source of heat near the fuel.
Allworkwith fuelmust be performed
outdoors only. Spilled fuel must be
wiped away immediately.
2. Safety Precautions

5MS 192 T
3. Specifications
3.1 Engine
MS 192 T
Displacement: 30.1 cm3
Bore: 37 mm
Stroke: 28 mm
Engine power to ISO 7293 1.3 kW (1.8 HP)
at 9500 rpm
Max. permissible engine speed
(with bar and chain): 13500 rpm
Idle speed: 3000 rpm
Clutch: Centrifugal clutch without linings
Clutch engages at: 4150 rpm
Crankcase leakage test
at gauge pressure: 0.5 bar
under vacuum 0.5 bar
3.2 Fuel System
Carburetor leakage test at
gauge pressure: 0.8 bar
Operation of tank vent at
gauge pressure: 0.3 bar
Fuel: as specified in instruction
manual
3.3 Ignition System
Air gap between ignition
module and fanwheel: 0.15...0.35 mm
Spark plug (suppressed): NGK BPMR 7 A
Electrode gap: 0.5 mm
3.4 Chain Lubrication
Fully automatic, speed-controlled oil pump with rotary piston
Oil delivery rate: 6.5 - 8.5 cm³ at 10,000 rpm

6MS 192 T
3.5 Tightening Torques
DG screws are used in polymer and light metal components. These screws form a permanent thread when they
are installed for the first time. Screws can be removed and installed as often as necessary without impairing the
strength of the screwed assembly, provided that the specified tightening torque is observed.
For this reason, it is essential to use a torque wrench.
Fastener Thread size For component Tightening
torque Remarks
Nm
Screw DG 4x15 Chain tensioner cover plate / engine
housing 2,5
Screw D 6x13 Collar screw for guide bar, rear 6,0
Collar screw DG 8x18 Collar screw for guide bar, front 16,0
Screw B 4.2x9.5 Cover plate/ screen/ muffler 2,0
Screw P 4x12 Cover/ sprocket cover/ engine housing
tensioner 2,5
Nut M 5 Filter base/ handle housing, 1st stage
aluminium 1,5
Nut M 5 Filter base/ handle housing, 1st stage 2,0
Nut M 5 Filter base/ handle housing, 2nd stage
aluminium 2,5
Nut M 5 Filter base/ handle housing, 2nd stage 3,5
Screw P 6x19 Handle housing/ front handle 6,0
Screw P 4x12 Handle moulding/ handle housing 1,5
Screw P 6x19 Retaining plate/ loop/ engine housing 6,0
Screw DG 5x20 Engine pan/ cylinder 8,0
Screw P 5x16 Bearing plug/ handle housing 4,0
Screw P 5x16 Bearing plug/ engine housing, sprocket
side 4,0
Screw P 5x16 Bearing plug/ engine housing, fan side 4,0
Screw P 5x16 Fan housing/ engine housing 4,0
M 8x1 L Carrier 25,0
Screw DG 5x20Z Engine housing/ cylinder 8,0
Screw DG 4x20 Oil pump/ engine pan 4,5
Screw P 4x12 Annular buffer, support/ engine housing 2,5
Screw P 5x29.6 Annular buffer/ handle housing 5,0
Screw DG 5x20 Muffler / cylinder 9,0
Nut M 8X1 Flywheel/ crankshaft 18,0
M 14x1.25 Spark plug 25,0
Screw DG 4x20 Ignition module/ cylinder 4,5

7MS 192 T
Use the following procedure when refitting a DG screw in an existing thread:
Place the screw in the hole and rotate it anticlockwise until it drops down slightly.
Tighten the screw clockwise to the specified torque.
This procedure ensures that the screw engages properly in the existing thread and does not form a new thread
and weaken the assembly.
Screwdriver speed when used in plastic material: DG screws max. 500 rpm.

8MS 192 T
4. Troubleshooting
4.1 Clutch
Problem Cause Remedy
Saw chain stops under load at full
throttle Clutch shoes badly worn Install new clutch
Clutch drum badly worn Install new clutch drum
Saw chain rotates at idle speed Idle speed too high Readjust with idle speed screw LA
(anticlockwise)
Clutch springs stretched or fatigued Replace clutch springs or install
new clutch
Clutch spring hooks broken Replace clutch springs
Loud noises Clutch springs stretched or fatigued Replace all clutch springs
Needle cage damaged Fit new needle cage
Clutch shoe retainer broken Fit new retainer
Clutch shoes and carrier worn Install new clutch

9MS 192 T
4.2 Chain Drive, Chain Brake, Chain Tensioner
Problem Cause Remedy
Chain sprocket wears rapidly Chain not properly tensioned Tension chain as specified
Wrong chain pitch Fit chain of correct pitch
Insufficient chain lubrication Check chain lubrication
Chain sprocket worn Fit new chain sprocket
Saw chain stops under load at full
throttle Clutch shoes badly worn Install new clutch
Clutch drum badly worn Install new clutch drum
Brake band stuck Check freedom of movement and
function of brake band
Saw chain rotates at idle speed Idle speed too high Readjust with idle speed screw LA
(anticlockwise)
Clutch springs stretched or fatigued Replace clutch springs or install
new clutch
Clutch spring hooks broken Replace clutch springs
Saw chain does not stop
immediately when brake is
activated
Brake spring stretched or broken Fit new brake spring
Brake band stretched, worn or
broken Fit new brake band
Clutch drum worn Install new clutch drum

10 MS 192 T
4.3 Chain Lubrication
In the event of trouble with the chain
lubrication system, check and
rectify other sources of faults before
disassembling the oil pump.
.
Problem Cause Remedy
Chain receives no oil Oil tank empty Fill up with oil
Oil inlet hole in guide bar is blocked Clean oil inlet hole
Intake hose or pick-up body
clogged or intake hose ruptured Fit new intake hose and pick-up body
Valve in oil tank blocked Clean or replace valve
Worm worn Replace worm
Oil pump damaged or worn Replace oil pump
Machine losing chain oil Oil pump housing defective Replace oil pump
Oil pump damaged or worn Replace oil pump
Oil pump delivers insufficient oil Oil pump worn Replace oil pump

11MS 192 T
4.4 Rewind Starter
Problem Cause Remedy
Starter rope broken Rope pulled out too vigorously as
far as stop or over edge, i.e. not
vertically
Fit new starter rope
Normal wear Fit new starter rope
Starter rope does not rewind Rewind spring broken Replacing the rewind spring
Spring insufficiently tensioned Check rewind spring and increase
tension
Very dirty or corroded Clean or replace rewind spring
Starter rope cannot be pulled out
far enough Rewind spring overtensioned Check rewind spring and reduce tension
Starter rope can be pulled out
almost without resistance
(crankshaft does not turn)
Guide peg on pawls or pawls
themselves are worn Fit new pawls
Spring clip fatigued Fit new spring clip
Starter rope is difficult to pull and
rewinds very slowly Starter mechanism is very dirty Thoroughly clean complete starter mechanism

12 MS 192 T
4.5 Ignition System
Exercise extreme caution while
carryingoutmaintenanceandrepair
work on the ignition system. The
high voltages which occur can
cause serious or fatal accidents.
Problem Cause Remedy
Engine runs roughly, misfires,
temporary loss of power Spark plug boot is loose Press boot firmly onto spark plug and fit new spring if necessary
Spark plug sooted, smeared with oil Clean the spark plug or replace if
necessary
Incorrect air gap between ignition
module and flywheel Set air gap correctly
Flywheel cracked
or has other damage or pole shoes
have turned blue
Install new flywheel
Ignition timing wrong, flywheel out
of adjustment, key in flywheel has
sheared off
Install new flywheel
Weak magnetization in flywheel –
pole shoes have turned blue Install new flywheel
Irregular spark Check operation of switch shaft and
ignition module
Faulty insulation on ignition lead or
short circuit wire, check ignition
lead / ignition module and replace if
necessary.
Check operation of spark plug
Clean the spark plug or replace if
necessary
Crankcase damaged (cracks) Replace crankcase

13MS 192 T
4.6 Carburetor
Problem Cause Remedy
Carburetor floods; engine stalls Inlet needle not sealing.
Foreign matter in valve seat or
cone
Remove and clean inlet needle or
clean carburetor
Inlet control lever sticking on
spindle Restore easy movement of inlet control lever
Helical spring not located on nipple
of inlet control lever Remove the inlet control lever and refit it correctly
Perforated disc on diaphragm is
deformed and presses constantly
against the inlet control lever
Fit a new metering diaphragm
Poor acceleration Idle jet too lean Turn low speed screw L
anticlockwise (richer), until engine
accelerates smoothly
Main jet too lean Turn high speed screw H
anticlockwise (richer), no further
than stop
Inlet control lever too low (relative
to correct installed position) Set inlet control lever flush with top edge of housing
Inlet needle sticking to valve seat Remove inlet needle, clean and
refit
Diaphragm gasket leaking Replace diaphragm gasket
Metering diaphragm damaged or
shrunk Fit new metering diaphragm
Impulse hose damaged or kinked Fit new impulse hose

14 MS 192 T
Problem Cause Remedy
Engine will not idle, idle speed too
high Throttle shutter opened too wide by idle speed screw LA Reset idle speed screw LA correctly
Oil seals / crankcase leaking Seal or replace oil seals /
crankcase
Engine stops when idling Idle jet bores or ports blocked
Clean the carburetor
Idle jet too rich or
too lean Set low speed screw Lcorrectly
Setting of idle speed screw
incorrect – throttle shutter
completely closed
Reset idle speed screw LA
correctly
Engine speed drops quickly under
load – low power Air filter dirty Clean the air filter
Throttle shutter not opened fully Check linkage
Tank vent faulty Clean tank vent or replace if
necessary
Fuel pick-up body dirty Clean the pick-up body or replace if
necessary
Fuel strainer dirty Clean fuel strainer in carburetor or
replace if necessary
Leak in fuel line between tank and
fuel pump Seal connections or install a new fuel line
Setting of high speed screw Htoo
rich Turn the high speed screw H clockwise (leaner) – max. up to the
stop.
Main jet bores or ports blocked Clean the carburetor
Pump diaphragm damaged or
fatigued Fit new pump diaphragm
Impulse hose damaged or kinked Fit new impulse hose

15MS 192 T
4.7 Engine
Always check and, if necessary,
repair the following parts before
looking for faults on the engine:
– Air filter
– Fuel system
– Carburetor
– Ignition System
Problem Cause Remedy
Engine does not start easily, stalls
at idle speed but operates normally
at full throttle
Oil seals in crankgear damaged Replace the oil seals
Crankcase leaking or damaged
(cracks) Seal or replace the crankcase
Engine does not deliver full power
or runs erratically Piston rings worn or broken Replace piston rings
Muffler / spark arresting screen
carbonized Clean the muffler (inlet and exhaust), replace spark arresting
screen, replace muffler if necessary
Air filter dirty Replace air filter
Fuel / impulse hose severely kinked
or damaged Fit new hoses and route them without kinks
Engine overheating Insufficient cylinder cooling. Air
inlets in fan housing blocked or
cooling fins on cylinder very dirty
Thoroughly clean all cooling air
openings and the cylinder fins

16 MS 192 T
Wear protective gloves
– risk of injury –
:Disengage the chain brake by
pulling the hand guard (1)
towards the front handle until it
engages.
1
217RA003 TG
:Unscrew the hex nut (arrow).
:Turn the screw anticlockwise to
relax the chain.
217RA004 TG
:Unscrew the nut (arrow) and
remove the sprocket cover (1).
217RA001 TG
1
:Slide the guide bar (1) towards
the clutch and remove the chain
from the guide bar.
– Remove the guide bar (1).
– Remove the chain (2) via the
sprocket.
217RA002 TG
1
2
– Reassemble parts in reverse
order.
:Fit the sprocket cover, ensuring
that the peg (arrow) engages in
the hole.
217RA021 TG
– Reassemble remaining parts in
reverse order.
– Tension the chain, b5.2
– Tightening torques, b3.5
5. Chain/ Spiked Bumper
5.1 Chain and Chain Guide

17MS 192 T
:Turn the screw clockwise to
tension the chain.
:Tighten the hex nut (arrow).
217RA076 TG
The chain (1) is correctly tensioned
when it rests against the underside
of the chain guide (arrow) and can
be pulled over the guide bar by
hand when the chain brake is
released.
If the chain is tensioned
1
217RA007 TG
excessively, this may result in
damage to the chain, guide bar and
sprocket, as well as its needle
bearing.
Sprocket cover with integrally
moulded chain catcher (1).
If the chain catcher has broken (2),
file down the stub and replace with
a replacement chain catcher (3).
1
2
217RA350 TG
– Remove the sprocket cover and
bar and chain, b5.1
:Remove the screw (arrow).
:Remove the chain catcher (3).
– Reassemble parts in reverse
217RA005 TG
3
order.
– Remove the sprocket cover and
bar and chain, b5.1
– Remove the chain catcher,
b5.3
:Remove the screw (arrow).
1
217RA006 TG
:Remove the spiked bumper (1).
– Reassemble parts in reverse
order.
5.2 Tensioning the Chain 5.3 Chain Catcher 5.4 Bumper Spike

18 MS 192 T
Bumper strips are fitted on the
engine housing to guide the saw
chain.
Worn bumper strips must be
replaced, otherwise the engine
housing may be damaged.
Remove the sprocket cover and bar
and chain, b5.1
:Prise off the bumper strips (1)
with a suitable tool.
217RA071 TG
1
1
:Insert the bumper strips so that
the peg is aligned in the recess
(arrows).
– Reassemble remaining parts in
reverse order.
217RA083 TG
– Troubleshooting, b4.1
– Remove the sprocket cover and
bar and chain, b5.1
:Release the twist lock (arrow).
:Remove carburetor box cover (1)
to the rear.
217RA008 TG
1
:Apply a suitable tool to the tab
(arrow) to prise the boot off the
spark plug (1).
1
217RA009 TG
:Unscrew the spark plug (1).
1
217RA010 TG
:Push the locking strip (1)
0000 893 5903 into the spark
plug hole so that "OBEN-TOP"
faces down.
1
217RA011 TG
:Unscrew the clutch (1).
The clutch has a left-hand thread.
1
217RA012 TG
5.5 Bumper Strips 6. Clutch

19MS 192 T
Disassembly
:Use hook (2) 5910 890 2800 to
remove the clutch springs (1).
217RA013 TG
2
1
– Pull the clutch shoes off the
carrier.
:Pull theretainers (1) offthe clutch
shoes.
217RA014 TG
1
– Clean all parts.
– Replace any damaged parts.
217RA015 TG
:Slip the retainers (1) onto the
clutch shoes.
217RA016 TG
1
:Fit the clutch shoes over the
arms (1) so that the series
number (2) is on the same side
as the raised hexagon (arrow).
217RA017 TG
12
:Clamp the clutch in a vice
(arrow).
217RA018 TG
:Attach one end of the clutch
spring (1) to the clutch shoes.
:Use the hook (2) 5910 890 2800
to attach the other end of the
spring and press it firmly into the
clutch shoe.
217RA019 TG
1
2
The tips of the retainers (arrows)
must match one another on the side
with the raised hexagon and the
series numbers must be visible on
the clutch shoes.
217RA020 TG
1137
1137
1137