Yamaha YT175J 1982 User manual

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

CHAPTER 1. GENERAL INFORMATION
MACHINE IDENTIFICATION .............................................. 1-1
Frame serial number .................................................. 1-1
Engine serial number ................................................. 1-1
( SPECIAL TOOLS ........................................................ 1-2
For
tune-up ......................................................... 1-2
For
engine service .....................•.............................. 1-2
For
chassis service ................................................... 1-3
For
electrical components ............................................. 1-4
Additional tools and supplies .......................................... 1-4

GENERAL INFORMATION
MACHINE IDENTIFICATION
Frame serial number
The frame serial number is stamped into the
right-sde
of the steering head pipe.
1. Frame serial number
NOTE: ______________________ __
The first three digits of these numbers are for
model identification; the remaining digits are
the unit production number.
Starting Serial Number:
YT175J ................ 5V7-000101
1-1
Engine serial number
The engine serial number is stamped into the
elevated part
of the right rear section of the
engine.

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
improper tools or improvised techniques.
Fortune-up
1. Timing light
2. Tachometer
For engine service
1. Dial gauge
PIN 90890-03002-00
2. Dial gauge stand
PIN 90890-01256-00
3. Dial gauge needle
PIN 90890-03099-00
1-2
Tools 1, 2, and 3 are use to set the ignition
timing.
4. Crankcase separation tool
PIN 90890-01135-00
This tool is use to split the crankcase as well
as remove the crankshaft from either case.
5. Crank installer pot
PIN 90890-01275-00
6. Crank installer bolt
PIN 90890-01275-00

7. Spacer
PIN 90890-01288-00
8. Crank installer bolt adapter
PIN 90890-01278-00
Tools
5, 6, 7, and 8 are use to install the
crankshaft.
9. Flywheel puller
PIN 90890-01189-00
This tool
is use to remove the flywheel
magneto.
1-3
10. Flywheel holding tool
PIN 90890-01235-00
Use this tool to hold the flywheel magneto
while removing or tightening the flywheel
magneto securing nut.
For chassis service
1. Steering nut wrench
PIN 90890-01051-00
Use this wrench to put the proper tension on
the steering head bearing.
2. Front-fork-cylinder holder
PIN 90890-01300-00
This tool is used
to loosen and tighten the
front fork cylinder holding bolt.

For electrical components
The use of these tools are described in
Chapter
6.
1. Pocket tester
PIN 90890-03104-00
2. Electro tester
PIN 90890-03021-00
1-4
Additional tool and supplies
1. Thickness gauge set
2. Torque wrench
3. Tire pressure gauge
4. Fluid mesuring cup
5. Micrometer
6. Slide caliper
7. Cylinder gauge
8. Magnetic stand
9. Grease gun
10. Yamalube 4-cycle oil
11. Yamalube 2-cycle oil
12. Yamabond
#4
13. Yamaha chain and cable lube or SAE
10W30
motor oil
14. Medium
weight wheel bearing grease
15. Locktit stud N'bearing mount (Red)

CHAPTER 2.
PERIODIC INSPECTIONS AND ADJUSTMENTS
INTRODUCTION ......................................................... 2-1
MAINTENANCE INTERVALS CHART ...................................... 2-1
ENGINE ................................................................ 2-3
Spark plug .......................................................... 2-3
Fuel
line ............................................................ 2-3
Over flow chamber ................................................... 2-3
Idle speed .......................................................... 2-3
Throttle cable ........................................................ 2-3
Throttle lever ........................................................ 2-4
Autolube pump cable adjustment ...................................... 2-4
Minimum pump stroke check and adjustment ............................ 2-4
Air bleeding ......................................................... 2-5
Engine oil .................................... '.' ..................... 2-6
Checking the water release valve ....................................... 2-6
Transmission oil ..................................................... 2-6
Checking ignition timing .............................................. 2-7
CHASSIS ............................................................... 2-8
Air cleaner .......................................................... 2-8
Front brake shoe inspection ........................................... 2-8
Rear
brake pad inspection ............................................. 2-8
Brake adjustment .................................................... 2-9
Drive chain tension check ............................................ 2-11
Drive chain tension adjustment ........................................ 2-11
Drive chain cleaning and lubrication ................................... 2-11
Steering head adjustment ............................................ 2-11
Wheel bearings ..................................................... 2-12
Fuel
cock .......................................................... 2-13
Tires .............................................................. 2-13
Cable
inspection and lubrication ...................................... 2-14
Brake and change pedals/front and rear brake levers ..................... 2-14
ELECTRICAL
........................................................... 2-15
Headlight bulb replacement .......................................... 2-15
Headlight beam adjustment .......................................... 2-15

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
The following charts should be considered strictly as a guide to general maintenance and lubrica-
tion intervals. You must take into consideration
~hat weather, terrain, geographical location, and
a variety of individual uses. This time schedule should be altered to match individual owner's re-
quirements. For example, if the machine is continually operated in an area of high humidity, then
all parts must be lubricated much more frequently that shown on the chart to avoid damage
caused by water to metal parts.
PERIODIC MAINTENANCE
Initial Thereafter every
Item Remarks 1 3 6 6 1
Month Months Months
Months Year
Cylinder head/Exhaust
system/
Decarbonize 0 0 0
Spark arrester
Spark plug Inspect/Cleaning
or replace as required 0 0 0 0
Air filter
Wet type- Must be washed and damped with
0 0 0
Yamalube 2-cycle Oil or SAE 10W30 motor oil
Water release valve Check operation/Foreign materials 0 0 0 1
Month
Check operation/Fittings 0 0 0
Carburetor Clean/Refit/Adjust 0
Autolube pump Check/ Adjust/ Air bleeding 0 0 0 0
'Brake system (complete) Check/Adjust
as required-Repair as required 0 0 0 3
Months
Drive chain Check/Adjust
as required/Replace as required 0 0 0 1
Month
Steering bearings Check/Adjust
as required/Replace as required 0 0
'Wheels and tires Chack pressure/Wear/Balance/ Run out 0 0 0 0
Fuel cock Clean/Flush tank
as required 0 0 0 0
"Lights Check operation/Replace as required 0 0 0 0
'Fittings/ Fasteners Tighten before each trip and/or ... 0 0 0 0
• Indicatespre-operation check Items.
2-1

LUBRICATION INTERVALS
Initial Thereafter every
Item Remarks Type 1 3 6 6 1
Month Months Months Months Year
"Transmission oil Replace/Warm engine Yamalube 4-cycle oir
or SAE 0 Check 0 0
before draining 1
OW30 type SE motor oil
Throttle lever and Apply lightly Lithium base grease 0 0
housing
Brake lever
Apply lightly Lithium base grease 0 0 0
Brake cam shaft Apply lightly
Lithium base grease 0 0 0
Drive chain Lubricate chain thoroughly
Motor oil SAE30 -50 0 0 0 1
Month
Front forks Drain
completely-check
Yamaha fork oil10wt or
0 0 1
specifications SAE 10W30type
SE motor oil Year
Steering bearings Inspect
thoroughly/pack Medium-weightwheel bearing Check 2
moderately grease Years
Wheel bearings Do
not over-pack Medium-weightwheel bearing 0
yearly or ...
grease
" Indicatespre-operation checkItems.
2-2

ENGINE
Spark plug
1. Check electrode condition and wear, in-
sulator color, and electrode gap.
2. Clean the spark plug with spark plug
cleaner
if necessary. Use a wire gauge
to adjust the plug gap to the specifica-
tion.
3. If the electrode becomes too worn,
replace the spark plug.
4. When installing the plug, always clean
the gasket surface, wipe
off any grime
that might be rresent on the surface
of
the spark plug, and torque the spark
plug properly.
Standard spark plug: NGK
BP7ES
Spark plug gap:
0.7 -0.8 mm (0.028 -
0.031 in)
Spark plug tightening torque:
20Nm(2.0m·kg,14.5ft·lb)
Fuel line
Check the fuel hoses and vacuum lines for
cracks or damage; replace
if necessary.
Over flow chamber
If gasoline begin to show up in the pipe II A" ,
loosen the three screws from over flow
chamber and completely drain gasoline from
the pipe
II A" and chamber.
Idle speed
1. Turn the pilot air screw until it lightly
seats, then back
it out to specification.
This adjustment can be made
with
engine stopped.
2-3
Air screw (Turns out): 1and 1/4
2. Startthe engine and let it warm up.
3. Throttle stop screw
Turn throttle stop screw in or
out to
achieve smooth engine operation at
specified idle speed.
Idling speed: 1,600 ±
50 r/min
NOTE: ______________________ __
The pilot air and throttle stop screws
are
separate adjustments but they must be ad-
justed at the same time
to achieve optimum
operating condition at engine idle speeds.
1. Throttle stop screw
2. Pilot air screw
Throttle cable
Loosen cable adjuster lock nut (at top of car-
buretor) and turn cable adjuster until
specified free play is obtained. Retighten lock
nut.
Free play: 1 -1.5 mm (0.04 -0.06 in)
1. Adjuster
2. Lock nut

Throttle lever
Loosen the lock nut and turn the adjuster un-
til there is the specified free play at throttle
lever.
1. Adjuster 2. Lock nut
Throttle lever play:
3 -5 mm (0.12 -0.2 in)
Autolube pump cable adjustment
Before adjusting the pump cable, adjust the
throttle cable free play.
1. Adjust the throttle cable free play of 1 -
1.5 mm (0.04 -0.06 in) at the cable ad-
juster on the carburetor.
2. Close the throttle lever completely, then
check
to see that the Autolube pump
plunger pin is aligned
with the mark on
the Autolube pump pulley.
Match mark: 0
1. Oil pump
4. Match mark
2. Pump cable
5. Guide pin
3. Adjust pulley
2-4
3. If the mark and pin are not in alignment,
loosen the cable length adjuster lock nut
on
top of crankcase cover and adjust
cable length until alignment is achieved.
4. Tighten adjuster locknut.
1. Cable adjuster 2. Lock nut
Minimum pump stroke check and ad-
justment
1. While running the engine idle, observe
the pump adjust plate carefully, and
stop the engine the moment
that the ad-
just plate moves
out to the limit.
2. Measure the gap
with the thickness
gauge between the raised boss on
the
pump adjust pulleyand the adjust plate.
1. Adjust plate 2. Adjust pulley
3. Thickness gauge
3. Repeat steps a. and b. above a few
times. When the gap measured is the
largest,
the pump stroke is considered to
be at a minimum.

NOTE: ______________________ __
When inserting the thickness gauge between
the adjusting plate and the adjusting pulley,
be careful so that either the plate or the pulley
is
not moved. In other words, do not force
the thickness gauge intothe gap.
Minimum pump stroke:
0.20 -0.25 mm (0.008 -0.010 in)
4. If clearance
is not correct, remove the
adjust plate lock
nut and the adjust
plate.
5. Remove or add an adjust shim as re-
quired.
1. Adjust shim
NOTE: ________________________ _
Thicken shims increase pump stroke and out-
put, thinner shims decrease pump stroke and
output.
Air bleeding
The Autolube Pump and delivery lines must
be bled on the following occasions:
• Whenever the Autolube tank has run
dry.
• Whenever any portion
of the Autolube
system
is disconnected.
• Ifthe machine lies on its side after falling
over.
2-5
1. Remove the pump cover and remove
the bleed screw.
1. Bleed screw
2. Keep the oil running out until air bubbles
disappear~
NOTE: ________________________ _
Check the bleed screw gasket, and if damag-
ed, replace
with a new one.
3. When air bubbles are expelled complete-
ly, tighten the bleed screw and install
the
pump cover.
4. Start the engine, pull the pump wire all
the way out to set the pump stroke to a
maximum.
NOTE: ________________________ _
It is difficult to bleed the distributor complete-
ly
with the pump stroke at a minimum, and
therefore the pump stroke should
be set to a
maximum.
5. Keep the engine running at about 2,000
r/min for two minutes or so, and both
distributor and delivery pipe can
be com-
pletely bled.

Engine oil
1. Place the machine on a level place and
startthe engine.
Engine oil:
Yamalube 2-cycle oil or
Air-cooled 2-stroke engine oil
Oil tank capacity:
1.3 L
(1.1 Imp qt, 1.4 US qt)
1. Oil tankfiller cap
NOTE: ______________________ __
Install the oil tank filler cap and push it fully
into the filler.
PUSH PUSH
2. Oil warning indicatorlight
When the engine oil level
is proper:
The oil warning light keeps going on
about 15 seconds (under high
temperatures) - 40 seconds (under low
temperatures) after the engine has
started, and then goes
off.
When the engine oil level is low:
The light keeps going on after the
engine has started.
If the light bulb is burnt out:
The light will
not come on after the
engine has started.
Checking the water release valve
Before starting off, be sure to check that the
valve
is closed. Before cleaning the air
cleaner element, check
if there is impurities in
the element case.
2-6
Transmission oil
Recommended oil:
Yamalube 4-cycle oil or
SAE 10W30
SE motor oil
1. Filler cap 2. Drain plug
Transmission oil capacity:
Periodic oil change: 0.7 -0.8 L
(0.6 -0.7 Imp qt, 0.7 -0.8 US qt)
Total: 0.8
-0.9 L
(0.7 -0.81mp qt, 0.8
-1.0 US qt)
Transmission drain plug torque:
20 Nm (2.0 m ·kg, 14.5ft ·Ib)

1. To check, warm up the engine for 2 - 3
minutes. Place the machine upright and
remove the oil level checking bolt.
If oil
flows out, the oil level
is correct. The
transmission oil should
be drained and
refilled every 6 months.
1. Checking bolt
Checking ignition timing
1. Ignition timing is checked with timing
light by observing the position
of the
stationary pointer marked on the
crankcase and the marks on the
flywheel magneto.
1. Mark 2. Stationary pointer
3. Timing light
2. Remove the crankcase cover (Ll.
3. Connect the timing light to the spark
plug lead wire.
4. Start the engine and keep
it running at
the specified speed.
Use a tachometer
for checking.
Specified engine speed: 1,600 ±
50 r/ min
2-7
5. While running the engine at the
specified speed, check
to see that the
stationary pointer is aligned with
the
magneto center mark. If the marks are
out of alignment, check the woodruff
key for damage and/or crankshaft for
damage.

CHASSIS
Air cleaner
1. Remove the air cleaner case cap and ele-
ment assembly.
2. Wash
the element gently, but
thoroughly, in solvent.
3. Squeeze excess solvent
out of element
and dry.
4. Pour CI small quantity of motor oil (SAE
10W
30) onto cleaner element and work
thoroughly into the porous foam
material. Element must
be damp with oil
but
not dripping.
5. Re-install the element assembly and
case cover.
NOTE:
______________________ __
Each time cleaner element maintenance is
performed, check the air inlet
to the cleaner
case
of obstructions. Check the air cleaner
joint rubber
to the carburetor and manifold
fittings
for an air-tight seal. Tighten all fittings
thoroughly
to avoid the possibility of un-
filtered air entering the engine.
2-8
engine with the air
cleaner element removed.
This will allow unfiltered air to enter,
causing rapid wear and possible engine
damage. Additionally, operation without
the cleaner element will affect car-
buretor jetting with subsequent poor
performance and possible engine
overheating.
Front brake shoe inspection
To check, examine the wear indicator posi-
tion while depressing the brake pedal. If the
indicator reaches
to the wear limit line,
replace the shoes.
Rear
brake pad inspection
Check to see that the brake operates correct-
Iy. Remove the disc cover, check the brake
pads
for damage and wear. If the thickness is
less than the specified value, replace the pad
as aset.

:: I
/1
~L~5mm
(0.02 in)
* This figure shows the wear limit of the pads as they are in-
stalled in the caliper.
1. Pad thickness 2. Wearlimit
Wear limit: 1.5 mm (0.06 in)
Brake adjustment
1. Front brake lever
Front brake cable free play can
be ad-
justed
to suit rider preference, but a
minimum free play
of 9 -15 mm (0.35-
0.59 in) should be maintained.
Free play can be adjusted at handle bar
lever and brake shoe plate.
a. Loosen the lock nut on the brake lever
holder, fullyturn the adjuster in.
b. Turn the adjuster on the shoe plate in or
out until proper adjustment is achieved.
c. Unless the shoe plate adjuster helps br-
ing a proper play, turn
to the lever holder
adjuster.
d. Tighten the lock nut.
2-9
1. Adjuster
2. Lock nut
2. Brake pedal
WARNING:
When adjusting the rear brake, first ad-
just the brake caliper, adjust the brake
pedal, then adjust the brake lever.
a. Loosen the brake lever lock nut and
screw in
the adjuster until tight.
1. Adjuster
2. Lock nut
3. Brakelever(l)

b. Loosen the brake pedal cable lock nuts,
adjust the brake caliper lever position so
that the cable length from the frame
to
the cable end is 62 mm (2.4 in), as il-
lustrated.
After adjustment, tighten the
locknuts.
1. Brake caliper lever
2. Locknut
3. Brake pedal cable
4. Rear brake cable
c. Loosen the caliper lock nut, and adjust
the play
of the brake pedal to 6 - 10 mm
(0.24 -0.39 in) by turning the adjusting
bolt. Then tighten the adjusting bolt lock
nut.
1. Adjusting bolt
2. Lock nut
Tightening torque:
15 Nm (1.5 m 'kg, 11 ft 'Ib)
3.
Rear brake lever
WARNING:
Never adjust the brake lever without first
adjusting the brake caliper and brake
pedal.
2-10
a. Loosen the brake cable lock nuts and
turn the adjuster so
that the rear brake
cable and brake caliper lever have no
play at all.
After adjusting, tighten the
lock nuts.
Omm
~
1. Brake caliper lever
2. Lock nut
3. Rear brake cable
b. Turn the adjuster so that the brake lever
has a play
of 9 - 15 mm (0.35 -0.59 in)
at its end. Next, tighten the locknut.
1. Adjuster
2. Locknut

Drive chain tension check
Inspect the drive chain with both tires
touching the ground. Check the tension at
the position shown in the illustration. The
normal vertical deflection is approximately 5
-
10 mm (0.2 -0.4 in). If the deflection ex-
ceeds
10 mm (0.4 in), adjust the chain ten-
sion.
5-10mm
(0.2 -0.4in)
1. Inspection window
Drive chain tension adjustment
1. Loosen the rear wheel hub bolts.
2. Next, adjust chain play
to specification
byturning the chain puller adjuster.
1. Adjuster
3. Tighten the rear wheel hub bolts.
Tightening torque:
46 Nm (4.6 m ·kg,
33 ft-lb)
Drive chain cleaning and lubrication
This machine has a drive chain with small
rubber O-rings between the chain plates.
Steam cleaning, high-pressure washes, and
certain solvent can damage these O-rings.
Use only kerosene to clean the drive chain.
Wipe
it dry, and thoroughly lubricate it with
SAE 30 - 50 motor oil. Do not use any other
lubricants on the drive chain. They may con-
tain solvents
that could damage the O-rings.
2-11
D O-RING
Steering head adjustment
The steering assembly should be checked
periodically
for looseness.
1. Raise the front end of the machine so
that there is no weight on the front
wheel.
2. Grasp the bottom of the forks and gently
rock the
fork assembly backward and
forward, checking for looseness in the
steering assembly bearings.

3. If the steering head is loose, adjust it.
Remove the handlebar holder bolts
,
handlebar, breather pipe, cap bolts,
steering stem nut, and steering crown.
4.
Use a steering nut wrench to tighten t'1e
steering fitting nut until the steering
head
is tight but does not bind when the
forks
are turned.
1. Steering fitting nut
2. Steering nut wrench
5. Install the steering crown and retighten
the stem nut, cap bolts handlebar, and
handlebar holder bolts
in that order.
Tightening torque:
Steering stem nut:
65 Nm (6.5 m .kg, 47 ft-lb)
Cap bolt:
54 Nm (5.4 m' kg, 39 ft 'Ib)
Handlebar holder bolt:
34 Nm (3.4
m' kg, 24.5 ft 'Ib)
1. Handlebar holder bolt
2. Steering stem nut
3. Cap bolt
2-12
6. Recheck steering adjustment to make
sure there is no binding when the forks
are moved from lock
to lock. If
necessary, repeat the adjustment pro-
cedure.
Wheel bearings
If a rolling rumble is noticed and increases
with increasing wheel speed (not engine or
transmission speed), the wheel bearings may
be worn. Check the wheel bearings for both
the
front and rear wheels.
Front wheel
AXLE
.{~
COLLORA~ .
OILSEAL~
BEARING ~ c:; ~
SPACER / @~~ /
BEARING
OIL SEAL
\ .
AXLE NUT
~ ..
I

Rear wheel
AXLE NUT
\
......
......
@ .....
":,':,0 RING NUT
t. @)/ ":.~~:ASHER
• aj.,:,g'g ~4., AXLE
OIL SEAL
/~~~. ~,I
<;:::/ HUB ~EARING ~~
~N. BEARING /
.-;.~f(t:+'~ OIL SEAL .
@" ~@l •
.,., ~~Pl ~ '/"'lotrJ
P- "')
,,,.~ ..
~
LOCK WASHER 7~
RING NUT
Fuel cock
If either fuel cock is leaking or is. excessively
contaminated,
it should be removed from the
fuel tank and inspected.
dr~RING
- - _ O-RING
, v..",J
GASKET-g~ ~
FILTER CUP~ U
2-13
1. Remove the fuel tank and position it so
that fuel will not spill when the fuel cock
is removed.
2. Remove the fuel cock and inspect the
filter screen. Replace the filter
if it is
seriously contaminated.
3. Remove the screws on the front and rear
of the fuel cock; remove the plate,
gaskets, lever, and diaphragm.
4. Inspect all components, and replace any
that are damaged. If the diaphragm is
damaged in any
way or if the fuel cock
gasket surfaces
are scratched or corrod-
ed, the fuel cock assembly must be
replaced.
If there is abrasive damage to
any components, the fuel tank must be
drained and flushed.
5. Reassemble the fuel cock, and install it
on the fuel tank.
Tires
This model is equipped with low
pressure tires. Pay attention to the
following points:
Recommended tire pressure:
14.7 kPa (0.15 kg/cm2, 2.2 psi)
Vehicle load limit: 100 kg (220 Ib)
Tire size: 22 x 11-8
1. Excessive tire pressure (over 68.6
kPa (0.7
kg/cm2, 10 psi) may cause
tire to burst. Inflate tires very slow-
ly. Fast inflation could cause tire to
burst.
2. Too Iowa pressure (below 11.8 kPa
(0.12 kg/cm2, 1.8 psi)) will cause the
rim to dislodge from the tire.
3. Put the same pressure in both rear
tires. Uneven tire pressure will
severely affect the handling.
4. Set tire pressures cold.
Resistance to pressure:
68.6 kPa (0.7 kg/cm2, 10 psr)
Reference tire pressure:
14.7 kPa (0.15 kg/cm2, 2.2 psi)
Min. tire pressure:
11.8 kPa (0.12 kg/cm2, 1.8psi)