gas type YAMAHA YZ125LC 2003 Manuale duso (in Italian)

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:
Except for ZA:
Premium unleaded gasoline
only with a research octane
number of 95 or higher.
For ZA:
Premium gasoline

1-12
GEN
INFO
ESSENCE ET HUILE DE MELANGE DU MOTEUR
KRAFTSTOFF UND MOTORGEMISCHÖL
CARBURANTE E OLIO PER MISCELA PER MOTORI
KRAFTSTOFF UND
MOTORGEMISCHÖL
Öl im nachfolgend angegebenen Ver-
hältnis dem Kraftstoff beimengen.
Immer frischen Marken-Kraftstoff ver-
wenden und das Öl erst am Renntage
dem Kraftstoff beimengen. Niemals
ein Kraftstoff/Öl-Gemisch verwenden,
das mehr als einige Stungen alt ist.
ESSENCE ET HUILE DE
MELANGE DU MOTEUR
Mélanger le carburant à l’huile dans les
proportions indiquées ci-dessous. Utili-
ser systématiquement de l’essence
neuve et connue, mélanger l’huile et
l’essence le jour de la course. Eviter
l’emploi d’un mélange dont la prépara-
tion remonte à plus de quelques heures.
HINWEIS:
Falls es zu Zündfunkenklopfen
kommt, eine andere Benzin-Marke
oder Benzin mit einer höheren Oktan-
zahl verwenden.
dD
Niemals zwei verschiedene Ölsor-
ten zusammenmischen. Es kann zu
Ölklumpenbildung führen. Falls Sie
die Ölsorten wechseln möchten,
unbedingt zuvor den Kraftstoff-
behälter und die Vergaserschwim-
merkammer entleeren, bevor die
neue Ölsorte eingefüllt wird.
N.B.:
Si un cognement ou un cinglement sur-
vient, utiliser une marque d’essence dif-
férente ou une classe d’octane supérieu-
re.
ffF
Evitez de mélanger deux huiles diffé-
rentes dans le même mélange déssen-
ce, car elles pourraient se coaguler. Si
vous désirez changer d’huile, assu-
rez-vous de vider l’ancien mélange
contenu dans le réservoir et la cuve à
flotteur du carburant avant de verser
le nouveau.
IC160051
CARBURANTE E OLIO
PER MISCELA PER
MOTORI
Miscelare l’olio con la benzina nel rap-
porto specificato più sotto. Usare sem-
pre benzina fresca, di marca; e miscela-
re l’olio e la benzina il giorno della
gara. Non usare una miscela già prepa-
rata che abbia più di qualche ora.
NOTA:
Se si verifica detonazione o battito in
testa, usare una marca di benzina diver-
sa o una qualità con un numero di ottani
più alto.
iI
Non miscelare mai due tipi di olio
nella stessa miscela; potrebbe risul-
tarne un raggrumamento dell’olio. Se
si desidera cambiare tipo di olio, assi-
curarsi di scaricare la vecchia miscela
preparata dal serbatoio del carburan-
te e dalla vaschetta del carburatore
prima di riempirli con il nuovo tipo.
Huile de mélange
Huile préconisée:
Yamalube “2-R”
(Huile deux temps
Yamalube de course)
Proportions de
mélange: 30 : 1
Si indisponible, utilisez
une huile d’un type
équivalent.
Contenance du réservoir
d’essence:
8,0 L (1,76 Imp gal,
2,11 US gal)Capacità del serbatoio del
carburante:
8,0 L (1,76 Imp gal,
2,11 US gal)
Olio per miscela
Olio raccomandato:
Yamalube “2-R”
(Olio a 2 cicli per
corse Yamalube)
Rapporto di
miscelazioen: 30 : 1
Qualora non fosse
disponibile, utilizzare un
tipo d'olio equivalente.Mischöl
Empfohlenes Öl:
Yamalube „2-R“
(Yamalube Zwei-
takt-Rennöl)
Mischungsverhält-
nis: 30 : 1
Falls nicht verfügbar,
gleichwertigen Öltyp
wählen.
Kraftstofftank-
Fassungsvermögen:
8,0 L (1,76 lmp gal,
2,11 US gal)
Essence préconisée:
Excepté pour ZA:
Essence super sans
plomb d’un indice
d’octane recherche
de 95 ou plus uni-
quement.
Pour ZA:
Essence superCarburante
raccomandato:
Tranne per ZA:
Unicamente benzi-
na super senza
piombo con numero
di ottano research
95 e più.
Per ZA:
Benzina superEmpfohlenes Kraftstoff:
Ausgenommen für
ZA:
Nur bleifreies
Superbenzin mit
einer
Oktanzahl (Roz)
von 95 oder höher.
Für ZA:
Superbenzin

2-1
SPECGENERAL SPECIFICATIONS
Model name: YZ125LC (EUROPE)
YZ125R (USA)
YZ125(R) (CDN, AUS, NZ, ZA)
Model code number: 5UN1 (USA, CDN, ZA)
5UN2 (EUROPE)
5UN4 (AUS, NZ)
Dimensions:USA, ZAAUS, NZ EUROPE CDN
Overall length 2,134 mm←2,130 mm←
(84.0 in) (83.9 in)
Overall width 827 mm←←←
(32.6 in)
Overall height 1,318 mm 1,315 mm 1,311 mm 1,315 mm
(51.9 in) (51.8 in) (51.6 in) (51.8 in)
Seat height 993 mm←992 mm←
(39.1 in) (39.1 in)
Wheelbase 1,438 mm←←←
(56.6 in)
Minimum ground clearance 400 mm←398 mm←
(15.7 in) (15.7 in)
Basic weight:
With oil and full fuel tank 94.5 kg (208.3 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 8.7~11.0 : 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 0.65 L (0.57 Imp qt, 0.69 US qt)
Total amount 0.70 L (0.62 Imp qt, 0.74 US qt)
Coolant capacity (including all routes): 0.95 L (0.84 Imp qt, 1.00 US qt)
Air filter: Wet type element
Fuel:
Type Except for ZA: Premium unleaded gasoline
only with a research octane
number of 95 or higher
For ZA: Premium gasoline
Tank capacity 8.0 L (1.76 Imp gal, 2.11 US gal)
EC200000
SPECIFICATIONSEC211000
GENERAL SPECIFICATIONS

2-2
SPECGENERAL SPECIFICATIONS
Carburetor:
Type/Manufacturer TMXχ
38SS/MIKUNI
Spark plug:
Type/Manufacturer BR9EG/NGK (resistance type)
Gap 0.5~0.6 mm (0.020~0.024 in)
Clutch type: Wet, multiple-disc
Transmission:
Primary reduction system Gear
Primary reduction ratio 64/19 (3.368)
Secondary reduction system Chain drive
Secondary reduction ratio 49/13 (3.769)
Transmission type Constant mesh, 5-speed
Operation Left foot operation
Gear ratio: 1st 30/13 (2.308)
2nd 28/15 (1.867)
3rd 29/19 (1.526)
4th 24/19 (1.263)
5th 25/23 (1.087)
Chassis:USA, ZA, AUS, NZEUROPE,CDN
Frame type Semi double cradle←
Caster angle 25.6° 25.4°
Trail 108 mm (4.25 in) 104 mm (4.09 in)
Tire:
Type With tube
Size (front) 80/100-21 51M
Size (rear) 100/90-19 57M
Tire pressure (front and rear) 100 kPa (1.0 kgf/cm2, 15 psi)
Brake:
Front brake type Single disc brake
Operation Right hand operation
Rear brake type Single disc brake
Operation Right foot operation
Suspension:
Front suspension Telescopic fork
Rear suspension Swingarm (link type monocross suspension)
Shock absorber:
Front shock absorber Coil spring/oil damper
Rear shock absorber Coil spring/Gas, oil damper
Wheel travel:
Front wheel travel 300 mm (11.8 in)
Rear wheel travel 315 mm (12.4 in)
Electrical:
Ignition system CDI magneto
2

2-7
SPECMAINTENANCE SPECIFICATIONS
EC212201
CHASSIS
Item Standard Limit
Steering system:
Steering bearing type Taper roller bearing …
Front suspension: USA, CDN, ZA EUROPE
AUS, NZ
Front fork travel
300 mm (11.8 in)← …
Fork spring free length
460 mm (18.1 in)← 455 mm (17.9 in)
Spring rate, STD K=4.02 N/mm K=Approx.…
(0.410 kg/mm, 4.02 N/mm
23.0 lb/in) (0.410 kg/mm, 23.0 lb/in)
Optional spring/Spacer Yes ←…
Oil capacity 568 cm
3 ← …
(20. 0 Imp oz,
19. 2 US oz)
Oil level
135 mm (5.31 in)← …
80~150 mm ←…
(From top of outer tube with inner tube(3.15~5.91 in)
and damper rod fully compressed
without spring.)
Oil grade Suspension oil
←…
“01”
Inner tube outer diameter 46 mm (1.81 in) ←…
Front fork top end 5 mm (0.20 in)
←…
Rear suspension: USA, CDN, ZA EUROPE
AUS, NZ
Shock absorber travel
132 mm (5.20 in)← …
Spring free length
260 mm (10.24 in) 275 mm (10.83 in)…
Fitting length
251 mm (9.88 in)262 mm (10.31 in)…

240.5~258.5 mm 255.5~273.5 mm…
(9.47~10.18 in)
(10.06~10.77 in)
Spring rate, STD K=44.0 N/mm K=Approx. …
(4.50 kg/mm, 46.0 N/mm
252.0 lb/in) (4.70 kg/mm, 263.2 lb/in)
Optional spring Yes ←…
Enclosed gas pressure 1,000 kPa ←…
(10 kg/cm
2,
142 psi)
Swingarm: Swingarm free play limit
End …
1.0 mm (0.04 in)
Side clearance …
0.2~0.9 mm
(0.008~0.035 in)

2-7
SPECCARACTERISTIQUES D’ENTRETIEN
PARTIE-CYCLE
Article Standard Limite
Direction:
Type de roulement de direction Roulement à rouleaux conique …
Suspention avant: USA, CDN, ZA EUROPE
AUS, NZ
Débattement de fourche avant
300 mm (11,8 in)← …
Longueur libre de ressort de fourche
460 mm (18,1 in)← 455 mm (17,9 in)
Course de ressort, STD K=4,02 N/mm K=Approx. …
(0,410 kg/mm, 4,02 N/mm
23,0 lb/in) (0,410 kg/mm, 23,0 lb/in)
Ressort/entretoise optionnel Oui ←…
Quantité d’huile 568 cm
3 ← …
(20, 0 Imp oz,
19, 2 US oz)
Niveau d’huile
135 mm (5,31 in)← …
80~150 mm ←…
(Du tuyau externe supérieur avec le tuyau (3,15~5,91 in)
intérieur et la tige d’amortisseur complé-
tement appuyé sans le ressort.)
Grade d’huile
Huile de suspension ← …
“01”
Diamètre extérieur de tube interne 46 mm (1,81 in)
←…
Extrémite supérieure de fourche avant 5 mm (0,20 in)
←…
Suspension arrière: USA, CDN, ZA EUROPE
AUS, NZ
Débattement d’amortisseur
132 mm (5,20 in)← …
Longueur de ressort libre
260 mm (10,24 in) 275 mm (10,83 in)…
Longueur de raccord
251 mm (9,88 in)262 mm (10,31 in)…

240,5~258,5 mm 255,5~273,5 mm…
(9,47~10,18 in) (10,06~10,77 in)
Course de ressort, STD K=44,0 N/mm K=Approx. …
(4,50 kg/mm, 46,0 N/mm
252,0 lb/in) (4,70 kg/mm, 263,2 lb/in)
Ressort optionnel Oui ←…
Pression de gas enfermé 1.000 kPa ←…
(10 kg/cm
2,
142 psi)
Bras oscillant: Limite de jeu de bras oscillatnt
Extrémité …
1,0 mm (0,04 in)
Latéral …
0,2~0,9 mm
(0,008~0,035 in)

3-13
INSP
ADJ
TRANSMISSION OIL REPLACEMENT
3. Check:
9Transmission oil level
EC35K002
TRANSMISSION OIL REPLACEMENT
1. Start the engine and warm it up for several
minutes and wait for five minute.
2. Place the machine on a level place and hold
it on upright position by placing the suitable
stand under the engine.
3. Place a suitable container under the engine.
Transmission oil level checking steps:
9Remove the oil check bolt 1.
9Inspect the oil level.
NOTE:
Be sure the machine is positioned straight
up when inspecting the oil level.
w
Never attempt to remove the oil check bolt
just after high speed operation. The heat-
ed oil could spout out, causing danger.
Wait until the oil cools down.
Oil flows out Oil level is correct.
Oil does not flow out Oil level is low.
Add transmission
oil until oil flows
out.
9Inspect the gasket (oil check bolt), replace if
damaged.
9Tighten the oil check bolt.
Recommended oil:
Yamalube 4 (10W-30) or SAE
10W-30 type SE motor oil
Oil check bolt:
10 Nm (1.0 m•kg, 7.2 ft•lb)

3-38
ELECTRICAL/SPARK PLUG INSPECTION
INSP
ADJ
EC370000
ELECTRICAL
EC371001
SPARK PLUG INSPECTION
1. Remove:
9Spark plug
2. Inspect:
9Electrode 1
Wear/Damage Replace.
9Insulator color 2
Normal condition is a medium to light tan
color.
Distinctly different color Check the
engine condition.
NOTE:
When the engine runs for many hours at low
speeds, the spark plug insulator will become
sooty, even if the engine and carburetor are in
good operating condition.
3. Measure:
9Plug gap a
Use a wire gauge or thickness gauge.
Out of specification Regap.
4. Clean the plug with a spark plug cleaner if
necessary.
5. Tighten:
9Spark plug
NOTE:
9Before installing a spark plug, clean the
gasket surface and plug surface.
9Finger-tighten athe spark plug before torquing
to specification b.
Spark plug gap:
0.5~0.6 mm (0.020~0.024 in)
Standard spark plug:
BR9EG/NGK (resistance type)
20 Nm (2.0 m•kg, 14 ft•lb)

5. Festziehen:
9Zündkerze
HINWEIS:
9Vor dem Einbau einer Zündkerze, die
Dichtfläche und die Zündkerze gründ-
lich reinigen.
9Die Zündkerze mit den Fingern festzie-
hen aund erst danach mit dem vorge-
schriebenen Anzursmoment bfesti-
ziehen.
5. Serrer:
9Bougie
N.B.:
9Avant de monter une bougie, nettoyer
son plan de joint et son filetage.
9Serrer la bougie à la main aavant de
la serrer au couple correct b.
3-38
PARTIE ELECTRIQUE/VERIFICATION DE LA BOUGIE
ELEKTRISCHE EINRICHTUNGEN/INSPEKTION DER ZÜNDKERZE
PARTE ELETTRICA/ ISPEZIONE DELLA CANDELA
INSP
ADJ
ELEKTRISCHE
EINRICHTUNGEN
INSPEKTION DER ZÜNDKERZE
1. Ausbauen:
9Zündkerze
2. Prüfen:
9Elektrode 1
Verschleiß/Beschädigung 
Erneuern.
9Farbe des Porzellankörpers 2
Bei normalen Bedingungen
sollte eine mittelbis hellbraune
Verfärbung vorhanden sein.
Stark abweichende Verfärbung
 Den Motorzustand kontrol-
lieren.
HINWEIS:
Wenn der Motor für viele Stunden mit
niedriger Drehzahl läuft, dann wird der
Zündkerzen-Isolator verölt, auch wenn
sich Motor und Vergaser in gutem
Betriebszustand befinden.
3. Messen:
9Elektrodenabstand a
Eine Drahtmeßlehre oder eine
Fühlerlehre verwenden.
Abweichung von Spezifikation
Einstellen.
4. Wenn erforderlich, die Zündker-
zen mit einem Kerzenreinigungs-
gerät reinigen.
IC370000
PARTE ELETTRICA
IC371001
ISPEZIONE DELLA CANDELA
1. Togliere:
9Candela
2. Ispezionare:
9Elettrodo 1
Usura/Danni Sostituirlo.
9Colore dell’isolatore 2
La condizione normale è un
colore tannino medio-chiaro.
Colore nettamente diverso 
Controllare le condizioni del
motore.
NOTA:
Quando il motore gira per molte ore a
bassi regimi, l’isolatore della candela
diventa fuligginoso, anche se il motore
e il carburatore sono in buone condizio-
ni di funzionamento.
3. Misurare:
9Distanza tra le candele a
Usare un calibro per fili metalli-
ci o uno spessimetro.
Fuori specifica Ridistanziar-
le.
4. Pulire la candela con un pulitore
per candela, se necessario.
PARTIE ELECTRIQUE
VERIFICATION DE LA BOUGIE
1. Déposer:
9Bougie
2. Examiner:
9Electrode 1
Usure/endommagement 
Changer.
9Couleur de l’isolateur 2
Une teinte légèrement brunâtre
correspond à l’état normal des
électrodes.
Teinte franchement différente 
Contrôler l’état du moteur.
N.B.:
Lorsque le moteur tourne pendant de
nombreuses heures à régimes lents,
l’isolant de bougie d’allumage se
couvre de suie, même si le moteur et le
carburateur sont en bon état de marche.
3. Mesurer:
9Ecartement des électrodes a
Utiliser un calibre pour câble ou
un calibre d’épaisseur.
Hors spécificationRégler.
4. Si nécessaire, nettoyer la bougie
avec un appareil de nettoyage de
bougie.
Ecartement des électrodes:
0,5~0,6 mm
(0,020~0,024 in)
Distanza tra le candele:
0,5~0,6 mm
(0,020~0,024 in)
Elektrodenabstand:
0,5~0,6 mm
(0,020~0,024 in)
Bougie standard:
BR9EG/
NGK (type à résistance)Candela normale:
BR9EG/
NGK (tipo di resistenza)
Standard-Zündkerzen:
BR9EG/
NGK (Widerstand, Typ)
20 Nm (2,0 m•kg, 14 ft•lb)20 Nm (2,0 m•kg, 14 ft•lb)20 Nm (2,0 m•kg, 14 ft•lb)
5. Serrare:
9Candela
NOTA:
9Prima di installare una candela, pulire
la superficie della guarnizione e la
superficie della candela.
9Serrare a mano ala candela prima di
serrarla secondo la specifica b.

5-60
CHASREAR SHOCK ABSORBER
EC586000
HANDLING NOTE
w
This shock absorber is provided with a
separate type tank filled with high-pressure
nitrogen gas. To prevent the danger of ex-
plosion, read and understand the following
information before handling the shock ab-
sorber.
The manufacturer can not be held respon-
sible for property damage or personal in-
jury that may result from improper han-
dling.
1. Never tamper or attempt to disassemble
the cylinder or the tank.
2. Never throw the shock absorber into an
open flame or other high heat. The shock
absorber may explode as a result of ni-
trogen gas expansion and/or damage to
the hose.
3. Be careful not to damage any part of the
gas tank. A damaged gas tank will impair
the damping performance or cause a
malfunction.
4. Take care not to scratch the contact sur-
face of the piston rod with the cylinder;
or oil could leak out.
5. Never attempt to remove the plug at the
bottom of the nitrogen gas tank. It is very
dangerous to remove the plug.
6. When scrapping the shock absorber, fol-
low the instructions on disposal.
EC587000
NOTES ON DISPOSAL (YAMAHA DEAL-
ERS ONLY)
Before disposing the shock absorber, be sure to
extract the nitrogen gas from valve 1. Wear eye
protection to prevent eye damage from escaping
gas and/or metal chips.
w
To dispose of a damaged or worn-out
shock absorber, take the unit to your
Yamaha dealer for this disposal procedure.