Yamaha XT550J User manual

_YAMAHA
LIT-11616-03-00 5Y1-28197-10

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NOTICE
This manual was written by the Yamaha Motor Company primarily for use by Yamaha dealers
and their qualified mechanics. It is not possible to put an entire mechanic's education into one
manual, so it is assumed that persons using this book to perform maintenance and repairs on
Yamaha motorcycles have a basic understanding
of the mechanical concepts and procedures in-
herent
to motorcycle repair technology. Without such knowledge, attempted repairs or service
to this model may render it unfit to use and/ or unsafe.
This model
has been designed and manufactured to perform within certain specifications in
regard to performance and emissions. Proper service with the correct tools is necessary to en-
sure that the motorcycle will operate
as designed. If there is any question about a service pro-
cedure, it
is imperative that you contact a Yamaha dealer for any service information changes
that apply to this model. This policy is intended to provide the customer with the most satisfac-
tion from his motorcycle and
to conform with federal environmental qualityobjectives.
Yamaha Motor Company, Ltd.
is continually striving to improve all models manufactured by
Yamaha. Modifications and significant changes
in specifications or procedures will be forwarded
to all Authorized Yamaha dealers and will, where applicable, appear in future editions of this
manual.
NOTE:
______________________________________________________ __
This Service Manual contains information regarding periodic maintenance to the emission con-
trol system for the XT550J. Please read this material carefully.
Particularly important information is distinguished in this manual bythe following notations:
NOTE: A NOTE provides key information to make procedures easier or clearer.
CAU11ON: A CAUTION indicates special procedures that must be followed to avoid damage
to the motorcycle.
WARNING:
A WARNING indicates special procedures that must be followed to avoid injury
to a motorcycle operatoror person inspecting or repairing the motorcycle.
"
SERVICE DEPT.
INTERNATIONAL DIVISION
YAMAHA MOTOR CO., LTD.

GENERAL INFORMATION
PERIODIC INSPECTIONS
AND
ADJUSTMENTS
ENGINE OVERHAUL
CARBURETION
CHASSIS
ELECTRICAL
APPENDICES

CHAPTER·'. GENERAL INFORMATION
MOTORCYCLE IDENTIFiCATION ........ ........................ 1-1
A. Frame Serial Number .. . .... .. ............. . .................. 1-1
B. Engine Serial Number .......................... ... ....... ..... 1-1
C. Vehicle Identification Number . ..... . .................... . ...... 1-1
MAIN FEATURES. ............................................. 1-2
A. Dry Sump System and Monocross Suspension
............... . ..... 1-2
B. Four-Valve Engine ........................................... 1-3
C. Yamaha Duo Intake System (YDIS) ............... . .............. 1-4
D. Kick Synchronous Automatic Decompression ...................... 1-5
E. D. C. Lighting System ......................................... 1-6
F. Detachable Lighting System
.... . ... . ................ . ......... 1-7
G.
Fuel Tank Cap with Check Valve ................................ 1-8
SPECIAL TOOLS. .............................................. 1-9
A. For Tune-up .......... . ... ... ............ . .................. 1-9
B. For Engine Service ............ . .............................. 1-9
C. For Chassis Service ......... .. .............................. 1-12
D. For Electrical Components ..... . .............................. 1-12

GENERAL INFORMATION
MOTORCYCLE
IDENTIFICATION
A. Frame Serial Number
The frame serial number is stamped into the
right side
of the steering head pipe.
1. Frame Serial Number
Starting Serial Number:
XT550J .............. . ..... 5Y1-000101
B. Engine Serial Number
The engine serial number is stamped into the
elevated part of the right section of the
engine.
NOTE: ______________________ __
The first three digits of these numbers are for
model identification; the remaining digits are
the unit production number.
1-1
c. Vehicle Identification Number
The vehicle identification number is on the
left side of the steering head pipe.
1. Vehicle Identification Number

MAIN FEATURES
A. Dry Sump System and Monocross Suspension
The XT550J, which inherits the traditional XT500
dry sump system, features monoshock suspen-
sion, light weight, and a
new diamond-shaped
frame
with integrated oil tank.
1-2

B. Four-Valve Engine
Newly designed compact engine equipped with:
S.O.H.C., 4-Valve head, Dual intake and dual ex-
haust ports,gear-driven balancer,Yamaha Duo In-
take System (YDIS), and 5-speed transmission
1-3
\

C. Yamaha Duo Intake System (YOIS)
For this system, the primary carburetor and the secondary carburetor are equipped as a unit:
A cable-operated-slide type functions
as the primary carb, and a vaccum-controlled-slide type
provides asecondary bore. The engine has a4-valve head, and each carb
has its own intake port
and valve. Although each carb bore and intake port
is smaller than that of a more conventional
engine, their conbined area is about 20% greater than a single, larger carb and intake layout.
Flow efficiency
of both the intake and exhaust sides is substantially improved. From idle to about
half throttle, the primary carb supplies the air-fuel mixture, and almost the entire intake charge
enters through just one valve; since the 4-valve layout offsets the intake ports relative
to the
cylinder-bore axis, a strong YICS-type swirl is produced in the low-to-medium rpm range.
Combustion efficiency
is significantly enhanced, resulting in improved fuel economy. In addi-
tion, the single small bore provides excellent low- and medium-speed throttle response due to
the high air velocity in the venturi. This eliminates the need for a mechanical accelerator pump,
allowing minimal carb height and ample room for the Monocross rear suspension. As the throttle
is turned from half to wide open, a linkage between the carburetors gradually opens the
secondary-carb butterfly. The vaccum-controlled slide
in the secondary carb opens as engine
demand builds, providing superb mid-range smoothness. With both slides fully open, the engine
receives more mixture and produces more powerthan a regular single-carb machine.
SECONDARY
CARB
PRIMARY CARB
1-4
Top view
EXHAUST
INTAKE

D. Kick Synchronous Automatic Decompression
The kick-starting mechanism is interlinked with one of the exhaust valves, thus automatically
decompressing the combustion chamber for ease in kick-starting. Combined with electronic ad-
vance ignition, kick-starting is free from possible kickback. Correct adjustment is required of this
kick-synchronous automatic decompression system for effective performance.
1-5

E. DC Lighting System (12V 45/45 Watt with sealed beam)
The DC lighting system provides a steady power source, enabling all lights to keep bright even at
low RPM.
This system also offers a safety advantage in that it keeps lights shining even when the engine is
stalled.
iii
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HEAD LIGHT VOLTAGE
AC LIGHTING
/
- --
-----
----'
DC LIGHTING
3 4 5 6 7 8
ENGINE R/MIN ( x 10 ')
1-6

F. Easy-maintenance Lighting System
The Easy-maintenance Lighting System is a
modular design integrating headlight and in-
strument panel into one easy-to-remove-and-
service package. A
few securing bolts, an elec-
trical connector, and the Easy-maintenance
Lighting System can
be removed for quick service.
1-7

G. Fuel Tank Cap with Check Valve
The fuel cap has a free steel ball inside it to prevent
fuel from spilling out through the cap breather
should the machineturnover.
This steel ball normally settles at the bottom, but
when the machine
is inclined to less than 30° from
the ground
as in a turnover, the ball is made to roll
accordingly while at the same time pushing up on
the valve seat
(see drawing).
When the machine is laid flat on the ground, the
O-ring on the valve contacts the tapered wall
of
the cap, thereby closing the breather passage
completely.
1-8

SPECIAL TOOLS
The proper special tools are necessary for
complete and accurate tune-up and
assembly. Using the correct special tool will
help prevent damage caused by the
use of
impropertools or improvised techniques.
A. For Tune-up
1. Valve adjusting tool
PIN. YM-08035
2. Compression gauge set
Adapter (M12) PIN. YU-33223
PIN. YU-33223-3
II
3. Oil pressure gauge adapter
PIN. YU-08030-1
This adapter is attached at the top of the oil filter cover after
removing
the air bleed screw.
1-9
4. Inductive timing light
""0., VII nan':l7
5. Inductivetachometer
PIN. YU-08036
B. For Engine Service
1. Universal clutch holder
PIN. YM-91042
This tool is used to hold the clutch when removing or installing
the clutch boss lock nut .

2. Valve guide reamer
PIN. YM-01227
This must be used when replacing the valve guide.
3. Valve seat cutter
PIN. YM-91043
Thistool is needed to resurface the valve seat.
4. Valve guide remover
PIN. Y.M-01225
This must be used to remove thevalve guides.
1-10
5. Valve guide installer
PIN. YM-04017
Thistool is needed for proper installation of the valve guides.
6. Valve spring compressor
PIN. YM-04019
This tool must be used for removing and installing the valve
assemblies.
7. Slide hammer set
PIN. YU-01083
These tools are used when removing the rocker arm shaft.
1. Bolt
PIN. YU-01083-1
2. Weight PIN. YU-01083-3

8. Crankshaft installing set
PIN. YU-90050
This tool is used when installing the crankshaft.
9. Adapter #10 crankshaft installing bolt
(M14)
PIN. YM-90069
14 mm x 1.5 adapter for installing the crankshaft, and removing
the final-gear drive pinion.
10. Crank pot spacer
PIN. YM-90070A
This tool is used when installing the crankshaft.
1-11
11. Crank protector
PIN. YM-04063
This tool protects the threads on the crankshaft.
12. Flywheel puller
PIN. YU-33270
This tool is used for removing the COl rotor.
13. Fu~lev~gauge
PIN. YM-01312
This tool is needed for checking thecarburetor fuel level.

14. Piston pin puller
PI N. YU-01304
This tool is used when removing the tight piston pin.
C. For Chassis Service
1. Front-fork-cylinder holder
PIN. YM-01327
T-handle
PIN. YM-01301 or YM-01326
This tool is used to loosen and tighten the front-fork-cylinder
bolt.
D. For Electrical Components
The
uses of these tools are described in
Chapter 6.
1. Pocket tester
PIN. YU-03112
1-12
2. Electro tester
PIN. YU-03021
3. Coil tester
PIN. YU-33261

CHAPTER 2.
PERIODIC INSPECTIONS AND
ADJUSTMENTS
INTRODUCTION . ............................................. 2-1
MAINTENANCE INTERVALS CHARTS .......................... 2-1
ENGINE . .................................................... 2-3
A. Valve Clearance
............................................ 2-3
B. Decompression System ...................................... 2-4
C. Spark Plug ................................................ 2-4
D. Crankcase Ventilation System ................................. 2-4
E. Fuel Line ................................................. 2-4
F. Exhaust System ............................................ 2-4
G. Idle Speed ................................................ 2-4
H. Engine Oil ................................................. 2-5
I. Oil Filter Replacement ....................................... 2-5
J. Engine Oil Replacement ...................................... 2-6
K. Oil Pressure Check .......................................... 2-6
L. Clutch Adjustment .......................................... 2-7
M. Checking Ignition Timing
..................................... 2-7
N. Compression Pressure Measurement ............................ 2-8
CHASSIS . ................................................... 2-8
A. Down Tube Strainer
......................................... 2-8
B. Air Filter .................................................. 2-9
C. Front and Rear Brake ........................................ 2-9
D. Cable Inspection and Lubrication .............................. 2-11
E. Brake and Change Pedals/ Brake and Clutch Levers/Sidestand ....... 2-11
F. Drive Chain .............................................. 2-11
G. Front Fork Oil Change ...................................... 2-12
H. Front Fork and Rear Shock Absorber Adjustment ................. 2-13
I. Steering Head Adjustment ................................... 2-14
J. Wheel Bearings ........................................... 2-14
K. Fuel Cock ................................................ 2-15
L. Tires and Wheels .......................................... 2-15
ELECTRICAL . ............................................... 2-16
A. Battery .................................................. 2-16
B. Circuit Breaker ............................................ 2-16

PERIODIC INSPECTIONS AND ADJUSTMENTS
INTRODUCTION
This chapter includes all information necessary to perform recommended inspections and ad-
justments. These preventive maintenance procedures, if followed, will ensure more reliable vehi-
cle operation and a longer service life. The need for costly overhaul work will be greatly reduced.
This information applies to vehicles already
in service and to new vehicles that are being
prepared for sale.
All service technicians should be familiar with this entire chapter.
MAINTENANCE INTERVALS CHARTS
Proper periodic maintenance is important. Especially important are the maintenance services
related to emissions control. These controls not only function to ensure cleaner air but are also
vital to proper engine operation and maximum performance. In the following maintenance
tables, the services related toemissions control are grouped separately.
PERIODIC MAINTENANCE EMISSION CONTROL SYSTEM
Initial Break- In
Thereafter Every
No. Item Remarks 1.
000km 5,000 km 4.
000km 8, OOOkm
1600 mil
13 ,000 mil 12,500 mil 15,OOOmi)
or 1 month
or 7 months or 6 months or 12 months
1 Valve clearance Check and adjust valve clearance
when engine is cold 0 0
2 Spark plugs Check condition; adjust gap/clean; 0 0 Replace
replace after i
nit ial 13 ,000 km 18 ,000 mil
Crankcase ventilation Check ventilation hose for cracks or
0 03 system damage; replace
if necessary
4 Fuel line Check fuel hose for c
ra c ks or damage;
replace if necessary 0 0
Check for leakage; retighten if necessary
5 Exhaust system replace gasket
lsi if necessary 0 0
6 Idle speed Check and adjust engine idle speed;
adjust cable free play
if necessary 0 0
7 Decompression Check and adjust decomp-cable free
play after valve clearance maintenance 0 0
2-1

GENERAL MAINTENANCE/LUBRICATION
Initial Break-In Thereafter Every
No. Item Remarks Type
l,oookm 5,oookm
4,oookm 8,oookm 16,oookm
(600mi) (3,ooomi) (2,500mi) (5,ooomi) (10,ooomi)
or 1 month or 7 months
Or 6 months or 12months or 24 months
Warm-upengine Yamalube 4-cycle
1 Engine oil oil or SAE20W40 0 0 0
before draining
type SE motor oil
Replace filter
element and clean
2 Oil filter down tube strainer -0 0 0
at initial 1,000 km
(600mi)
Wet type filter Yamalube 2-cycle
3 Air filter must be washed 0 0 0
and damped with oil oil
or equivalent
Adjust free play.
4 Brake system Replace shoes
if
-0 0 0
necessary
5 Clutch Adjust free play -0 0 0
Yamaha chain and
6 Drive chain Apply chain lube cable lube
or SAE Every 500 km (300 mil
thoroughly 10W30
motor oil
Control and Apply chain lube Yamaha chain and
7 meter cable thoroughly cable lube or SAE 0 0 0
10W30 motor oil
8 Rear arm Applygrease Lithium soap base 0 0
pivot shafts lightly grease
Brake pedal Yamaha chain and
9 Apply chain lube cable lube or SAE 0 0
shaft lightly 1
OW 130 motor oil
Side stand Yamaha chain and
10 pivots Apply chain lube cable lube
or SAE 0 0
and kick lightly
crank boss 10W30
motor oil
Drain completely; Yamaha
fork
11
Front fork refill
to
oil10wt. or
0
oil specification equivalent
Check bearings
Steering assembly
for
Medium weight
12
bearing and looseness; moder- wheel bearing 0 0 Repack
ately repack every
races 16,000 km grease
(10,ooomi)
Check bearings
13 Wheel for smooth rota- 0 0
-
bearings tion; replace if
necessary
Check specific
14 Battery gravity; check -0 0
breather pipe for
proper operation
Brakelclutch Yamaha chain and
15 lever pivot Applychain lube cable lube or SAE
shafts lightly 10W30
motor oil
2-2