engine oil YAMAHA YZ125LC 2005 Manuale duso (in Italian)

EC085002
ILLUSTRATED SYMBOLS
(Refer to the illustration)
Illustrated symbols 1to 7are designed as
thumb tabs to indicate the chapter’s number and
content.
1
General information
2Specifications
3Regular inspection and adjustments
4Engine
5Chassis
6Electrical
7Tuning
Illustrated symbols 8to rare used to identify
the specifications appearing in the text.
8
With engine mounted
9Special tool
0Filling fluid
qLubricant
wTightening
eSpecified value, Service limit
rResistance (Ω), Voltage (V), Electric current (A)
Illustrated symbols tto oin the exploded dia-
grams indicate grade of lubricant and location of
lubrication point.
t
Apply transmission oil
yApply engine mixing oil
uApply molybdenum disulfide oil
iApply lightweight lithium-soap base grease
oApply molybdenum disulfide grease
Illustrated symbols pto ain the exploded dia-
grams indicate where to apply a locking agent
and where to install new parts.
p
Apply locking agent (LOCTITER)
aUse new one
GEN
INFO
12
3
5
74
6
8
90
qw
er
tyu
io
pa
SPEC
INSP
ADJENG
CHASELEC
TUN
1C3-9-30-0 25/5/04 7:14 PM Page 14

EC0A0000
CONTENTS
CHAPTER 1
GENERAL INFORMATION
DESCRIPTION............................................1-1
MACHINE IDENTIFICATION......................1-2
IMPORTANT INFORMATION.....................1-3
CHECKING OF CONNECTION..................1-6
SPECIAL TOOLS........................................1-7
CONTROL FUNCTIONS.............................1-9
FUEL AND ENGINE MIXING OIL.............1-12
STARTING AND BREAK-IN.....................1-13
TORQUE-CHECK POINTS.......................1-16
CLEANING AND STORAGE....................1-17
CHAPTER 2
SPECIFICATIONS
GENERAL SPECIFICATIONS....................2-1
MAINTENANCE SPECIFICATIONS...........2-3
GENERAL TORQUE SPECIFICATIONS..2-12
DEFINITION OF UNITS............................2-12
CABLE ROUTING DIAGRAM..................2-13
CHAPTER 3
REGULAR INSPECTION
AND ADJUSTMENTS
MAINTENANCE INTERVALS.....................3-1
PRE-OPERATION INSPECTION AND
MAINTENANCE..........................................3-4
ENGINE.......................................................3-5
CHASSIS...................................................3-17
ELECTRICAL............................................3-38
1C3-9-30-0 25/5/04 7:14 PM Page 18

1-1
GEN
INFO
DESCRIPTION
EC100000
GENERAL INFORMATION
EC110000
DESCRIPTION
1Clutch lever
2“ENGINE STOP” button
3Front brake lever
4Throttle grip
5Radiator cap
6Fuel tank cap
7Kick starter
8Fuel tank
9Radiator
0Coolant drain bolt
qCheck bolt (Transmission oil level)
wRear brake pedal
eValve joint
rFuel cock
tAir cleaner
yDrive chain
uShift pedal
iStarter knob
oFront fork
NOTE:
9The machine you have purchased may differ
slightly from those shown in the following.
9Designs and specifications are subject to
change without notice.
1C3-9-30-1A 17/5/04 1:08 PM Page 2

1-4
GEN
INFO
IMPORTANT INFORMATION
EC133000
GASKETS, OIL SEALS AND O-RINGS
1. All gaskets, oil seals, and O-rings should be
replaced when an engine is overhauled. All
gasket surfaces, oil seal lips, and O-rings
must be cleaned.
2. Properly oil all mating parts and bearings
during reassembly. Apply grease to the oil
seal lips.
EC134000
LOCK WASHERS/PLATES AND COTTER
PINS
1. All lock washers/plates 1and cotter pins
must be replaced when they are removed.
Lock tab(s) should be bent along the bolt or
nut flat(s) after the bolt or nut has been
properly tightened.
EC135001
BEARINGS AND OIL SEALS
1. Install the bearing (s) 1and oil seal (s) 2
with their manufacturer’s marks or numbers
facing outward. (In other words, the
stamped letters must be on the side ex-
posed to view.) When installing oil seal(s),
apply a light coating of light-weight lithium
base grease to the seal lip(s). Oil the bear-
ings liberally when installing.
cC
Do not use compressed air to spin the
bearings dry. This causes damage to the
bearing surfaces.
EC132000
ALL REPLACEMENT PARTS
1. We recommend to use Yamaha genuine
parts for all replacements. Use oil and/or
grease recommended by Yamaha for as-
sembly and adjustment.
1C3-9-30-1A 17/5/04 1:08 PM Page 8

1-12
GEN
INFO
FUEL AND ENGINE MIXING OIL
EC160051
FUEL AND ENGINE MIXING OIL
Mix oil with the gas at the ratio specified below.
Always use fresh, name-brand gasoline, and mix
the oil and gas the day of the race. Do not use
premix that is more than a few hours old.
NOTE:
If knocking or pinging occurs, use a different
brand of gasoline or higher octane grade.
cC
Never mix two types of oil in the same
batch; clotting of the oil could result. If you
wish to change oil types, be sure to drain
the fuel tank and the carburetor float bowl
of old premix prior to filling with the new
type.
Fuel tank capacity:
8.0 L (1.76 Imp gal, 2.11 US gal)
Mixing oil
Recommended oil:
Yamalube “2-R”
(Yamalube racing 2-cycle oil)
Mixing ratio: 30 : 1
If unavailable, use an equivalent
type of oil.
Recommended fuel:
Premium unleaded gasoline
only with a research octane
number of 95 or higher.
1C3-9-30-1B 14/5/04 5:03 PM Page 2

1-14
GEN
INFO
STARTING AND BREAK-IN
EC194001
BREAK-IN PROCEDURES
1. Before starting the engine, fill the fuel tank
with a break-in oil-fuel mixture as follows.
2. Perform the pre-operation checks on the
machine.
3. Start and warm up the engine. Check the
idle speed, and check the operation of the
controls and the “ENGINE STOP” button.
4. Operate the machine in the lower gears at
moderate throttle openings for five to eight
minutes. Stop and check the spark plug
condition; it will show a rich condition during
break-in.
5. Allow the engine to cool. Restart the engine
and operate the machine as in the step
above for five minutes. Then, very briefly
shift to the higher gears and check full-throt-
tle response. Stop and check the spark
plug.
6. After again allowing the engine to cool,
restart and run the machine for five more
minutes. Full throttle and the higher gears
may be used, but sustained full-throttle op-
eration should be avoided. Check the spark
plug condition.
7. Allow the engine to cool, remove the top
end, and inspect the piston and cylinder.
Remove any high spots on the piston with
#600 grit wet sandpaper. Clean all compo-
nents and carefully reassemble the top end.
8. Drain the break-in oil-fuel mixture from the
fuel tank and refill with the specified mix.
9. Restart the engine and check the operation
of the machine throughout its entire operat-
ing range. Stop and check the spark plug
condition. Restart the machine and operate
it for about 10 to 15 more minutes. The ma-
chine will now be ready to race.
Mixing oil: Mixing ratio:
Yamalube “2-R” 15:1
1C3-9-30-1B 14/5/04 5:03 PM Page 6

1-18
GEN
INFO
CLEANING AND STORAGE
EC1B2001
STORAGE
If your machine is to be stored for 60 days or
more, some preventive measures must be taken
to avoid deterioration. After cleaning the ma-
chine thoroughly, prepare it for storage as fol-
lows:
1. Drain the fuel tank, fuel lines, and the carbu-
retor float bowl.
2. Remove the spark plug, pour a tablespoon
of SAE 10W-30 motor oil in the spark plug
hole, and reinstall the plug. With the engine
stop switch pushed in, kick the engine over
several times to coat the cylinder walls with
oil.
3. Remove the drive chain, clean it thoroughly
with solvent, and lubricate it. Reinstall the
chain or store it in a plastic bag tied to the
frame.
4. Lubricate all control cables.
5. Block the frame up to raise the wheels off
the ground.
6. Tie a plastic bag over the exhaust pipe out-
let to prevent moisture from entering.
7. If the machine is to be stored in a humid or
salt-air environment, coat all exposed metal
surfaces with a film of light oil. Do not apply
oil to rubber parts or the seat cover.
NOTE:
Make any necessary repairs before the machine
is stored.
1C3-9-30-1B 14/5/04 5:03 PM Page 16

2-1
SPECGENERAL SPECIFICATIONS
Model name: YZ125T1 (USA, CDN)
YZ125 (EUROPE, ZA)
YZ125T (AUS, NZ)
Model code number: 1C31 (USA, CDN, ZA)
1C32 (EUROPE)
1C34 (AUS, NZ)
Dimensions:USA, ZAAUS, NZ EUROPE, CDN
Overall length 2,134 mm←2,139 mm
(84.0 in) (84.2 in)
Overall width 827 mm←←
(32.6 in)
Overall height 1,316 mm←1,318 mm
(51.8 in) (51.9 in)
Seat height 992 mm←994 mm
(39.1 in) (39.1 in)
Wheelbase 1,443 mm←←
(56.8 in)
Minimum ground clearance 387 mm 388 mm 389 mm
(15.2 in) (15.3 in) (15.3 in)
Dry weight:
Without oil and fuel 86.0 kg (189.6 lb)
Engine:
Engine type Liquid cooled 2-stroke, gasoline
Cylinder arrangement Single cylinder, forward inclined
Displacement 124 cm
3(4.36 lmp oz, 4.19 US oz)
Bore ×Stroke 54 ×54.5 mm (2.126 ×2.146 in)
Compression ratio 8.6~10.7 : 1
Starting system Kick starter
Lubrication system: Premix (30 : 1)(Yamalube 2-R)
Oil type or grade (2-Cycle):
Transmission oil Yamalube 4 (10W-30) or SAE 10W-30 type SE
motor oil
Periodic oil change 0.66 L (0.58 Imp qt, 0.69 US qt)
Total amount 0.70 L (0.62 Imp qt, 0.74 US qt)
Coolant capacity (including all routes): 0.9 L (0.79 Imp qt, 0.95 US qt)
Air filter: Wet type element
Fuel:
Type Premium unleaded gasoline
only with a research octane
number of 95 or higher
Tank capacity 8.0 L (1.76 Imp gal, 2.11 US gal)
EC200000
SPECIFICATIONSEC211000
GENERAL SPECIFICATIONS
1C3-9-30-2A 25/5/04 7:13 PM Page 2

2-13
SPECCABLE ROUTING DIAGRAM
EC240000
CABLE ROUTING DIAGRAM
1Ground lead
2High tension cord
3Grommet
4Air vent hose
5Crankcase breather hose
6Y.P.V.S. breather hose
7Throttle cable
8Clutch cable
9Engine bracket (right)
0Engine bracket (left)
qAir vent hose (left)
wAir vent hose (right)
e“ENGINE STOP” button leadAPass the clutch cable on the
outside of the throttle cable and
“ENGINE STOP” button lead.
BInsert the tip of the fuel tank
breather hose into the hole in
the steering shaft cap.
CAlign the throttle cable locating
tape with the cable guide.
DPass through the cable guide
the throttle cable, “ENGINE
STOP” button lead and clutch
cable.
EPass the throttle cable and
clutch cable above the radiator
hose, and pass the “ENGINE
STOP” button lead below the
radiator hose.FInstall the ignition coil, side
core and ground lead together
to the frame.
GClamp the clutch cable to the
left engine bracket. Clamp the
clutch cable below the position-
ing grommet.
HPass the air vent hose back of
the throttle cable.
IPass the air vent hose, over-
flow hose and crankcase
breather hose between the
frame and connecting rod.
1C3-9-30-2B 27/5/04 4:18 PM Page 26

2-15
SPECCABLE ROUTING DIAGRAM
1“ENGINE STOP” button lead
2C.D.I. magneto lead
3Ignition coil lead
4Ground lead
5Positioning tape
6Protection tube
7C.D.I.unit
8Throttle cable
9Clutch cable
0Side core
qRadiator breather hoseAPass the high tension cord to
the left of the radiator hose.
BClamp to the frame the
“ENGINE STOP” button lead
and C.D.I. magneto lead.
Clamp them in front of the radi-
ator fitting boss.
CClamp to the frame the throttle
cable, clutch cable and ignition
coil lead.
DPass the C.D.I. magneto lead
and radiator breather hose
between the frame and the
right side of the radiator.
EInsert the C.D.I. unit band until
it stops at the C.D.I. unit stay.
FPass the C.D.I. magneto lead
and radiator breather hose
between the frame and the
radiator hose.GLocate the clamp ends in the
arrowed range.
1C3-9-30-2B 16/6/04 9:51 AM Page 30