Yamaha CS338G User manual

CHAPTER 1. GENERAL
1-1. Specifications . .
1- 2. Service data ..
1- 3. Construction ...
1-3 - 1. Engine ..
Power transmission.
Drive unit .
Steering system
Chassis ...
TABLE OF CONTENTS
1
3
5
5
12
14
15
.... .. ............. .. . 15
1- 3-2 .
1-3-3.
1-3 -4.
1-3-5.
1-3 - 6. Electrical system ................ .. .... .. ................ .. ................. ..
15
22
1-4. Tools.
CHAPT ER 2. E NGIN E
2-1. Removing the engine ........
.. ..... .. .. ... .. .. .. .. .. ...... 27
2-2. Manual starter . . .... .. .. .... .. .... .
.. .......... 31
Removal ............
.. ... . .. . .. .. .. ........... ...... ......... . 32
Disassembly . . ............ 32
2-2 - 1.
2-2-2.
2- 2-3.
2-2-4.
2-2-5.
Cleaning and inspection. ... ......... .. ...... .. .. .. ........ ..... .. .. .. .
.. .... .. . .. ... .. .... .. .. .......... .. .. 33
Assembly ............. ... ...... .. ..
33
Installation
2-3. Primary sheave
2-
3-1. Disassembly ... ... .. .. . ......... .. . ....... .. .. ..
2-3 -2. Cleaning and inspection .
2-3-3. Assembly.
2-4. Flywheel magneto ......... ... .. . .. .. .. .. .. .. .. .
34
35
36
37
38
39
40
41
46
47
47
48
49
50
2- 4-1. Removal ....... .. ...
2 -4-2.
2-4-3. Inspection .
.. .... .... ... ............ . ..
Installation
2-5. Carburetor ..
2-5 - 1. Removal ...
2- 5-2. Disassembly ..... .................... ..
2-5 - 3.
2- 5-4.
Cleaning and inspection
Assembly .......................... . ..... .. ...... .. .. ..
2-5 - 5. Installation
2-5 -6 . Adjustment. .... . .. .... . .. ... .. .. .. ............... .. .... ... ..
2-5-7 . Main jet replacement ............
.............
.. .... .. 51
51
53
2-6. Oil pump ... ...... ... ...... ......... . .. ....... .. .. ....... ...... ........... .. ........ .. .. .. ....... .. .. .. .. .. .. ....... .. 54
2-6- 1. Removal .. .. .......... .. .. .. .. .. ...... 54
2-6-2. Disassembly.. .................. . ...... ......... 55
2-6 - 3. Cleaning and inspection ...... .. .... 57
2 -6 -4. Assembly. 58
2-6-5. Installation ... 58
2- 7. Engine
2-7-1
2- 7-2.
2-7 - 3-
Disassembly ...
Cleaning and in spect ion ... ................. .. .......... .. .
Assembly . . ................ .. .... . ................. .
2-8. Engine mounting.
59
.. ............ ..... ............. ....... .. 62
63
.. .......... 70
.... .. ............ . .. ...... .. .. ............. 71

CHAPTER 3. POWER TRAIN
3-1. Secondary sheave ................ ................................................................................................ 75
3-1-1. Removal
.. ............................................ ............... ........ .. ........................ .. ............. .. 76
3-1-2 . Cleaning and inspection . .............. ............. ...... ................... 77
3-1 -3. Assembly .. ................. ....................... ................. .. ...... ................ ............................... 77
3- 1-4. Installation ........... ................... .. .......... ....... ............. .. 78
3-1-5. Adjustments.. .................... ............. ............. ............................ 78
3-2. Disc brake ..... ... ...................... ............... .............. ........ ..................... ........... 81
3-3 .
Removal ..
............................ ....... .......................... ........ ...............
82
3- 2-1 .
3-2-2.
3-2-3.
3-2-4.
Cleaning and inspection ....... .......... .... ........ .... ............ .... ...... ....... .. ......... ........... .... 82
Inspection .................. ........ ......... .. ............ ..... .. .. .. .. .....
......... 83
Adju s tment ................ .. .
Front axl
e.. .......... .................. ................................... .. . ..
3-3-1 . Removal ....................................... ...........
3-
3-2.
3- 3-3 .
3-3-4.
Disasse mbly ............. .. ...... ......................... .
Cleaning and ins
pection.......... .............. .... .. ..........
Assembly ..... .................... ............... .................. .... .. .. ................. .. .. ..
...................... 83
84
. .. .......... 85
86
86
87
3-3-5. Insta llation.. ................ ..... ............................................... ..... .......... .. 87
3-4. Rear axle .. ...... ..... ...................................... ........... ............... .. .......... ........ .... .............. ............ 88
3-4-1. Removal............ ...... .................. ........... ............ ...... .................. 89
3-4-2. Disasse mbly.. ...................... .............. ......................... ............... . .. ......... 89
3-4-3. Cleaning and in spection... ............. ...... ................ ... 90
3-4-4. Assembly. ................... .. ............ .. ........ ........... .......... .. ...... ............ ................. 91
3
-4-5 . In stallation ............ ........ ................ .......... .... .. .. ....... .. ............................................... 91
3-5. Bogie wheels ...... ........... .. ................................... ..... ... .............. .. ......... 92
3-5 - 1. Removal ................... ... ............ .......................... .. ........ .................... ........... .. ........ .. 93
Cleaning and inspection ................... .... .. .......... ... 93
3-5-2.
3-5-3.
Installation........................................ .... ...... .. .... .............
.................. 94
3-6. Drive track ......................... ........................ ................. ..
94
3- 6-1.
3-6-2 .
Removal ............
............... .... ............. .................. ....... ..... ........ .. ........... .. .... 94
Cleaning and inspection ....... ......................... ....... ....................... .
94
3-6-3. In stallatio n..... .. ..... ............ ........................ ................ . . . . ....... 95
3-6-4. Adjustment. .. ......................... ............. .. ...... 95
3-7. Chain housing.. .... ...... .. . ....................... ....... ................. ........................... 97
3-7-1 . Removal.... ................ ......................... ...................... ....... ........ .. .. 98
3-7-2. Disassembly.. ............. .. .. ................................ .............................. 98
3-7-3.
3-
7-4 .
3-7-5.
Cleaning and inspection ........
Assembly ....................... .. .......................... ............ .. .
Installation .. .. .. ................ ............. ... ....................... . .. ........ ..........
3-7-6. Chain adjustment ........................ ............... ..
CHAPTER 4. STEERING (SKI) AND CHASSIS
4-1. Steering ................................ .... ....... ................ ................. ....... ........................
4-1 - 1. Removal ................................................
Cleaning and inspection
............ .. ..
Installation......... ................................... ......... .. ... .. .
99
.. 100
. ............. . 100
... 101
.
103
4-1-2 .
4-1-3.
4-1-4.
Adjustment .............. ......................... ................ .. .... .. .. ........ .. .... .............. ..
. ...
104
. .. 105
.... 105
.. . 106
4-2. Ski .
4-
2-1.
4-2-2 .
4-2-3.
4-2-4.
.
............... 107
Removal .............. .............. ........... .............................. .. ............... ..
. 108
Cleaning and inspection .. .................................. ................ .. ........ ........... ..........
108
Installation ........ .......... .................... ................. .... .. .. . ............. .. .
................ 109
Adjustment ....... .. .................... .. .................. ..... .. ...... ........... ......... ......................
.109

4-3. Chassis and air shroud ............................ ....... ............. .............. ....
4-
3-1. Removal ................ ........... ..................... .. .. .. .......... ........ . .. ...... . .. .
4-3-2 . Install ation ... .................. ...... ...................... ...... ............ .. ....... .. ... ............... ......
.
.. 110
... 110
. 111
4-4. Rider's
seat.......... .. .................... ............... ........................... ................ .. .... ........ ... 111
4-
4-1. Removal .. .. ........ .. ........................... .. .. ...... .. .. .. .. .. .. . .. .......... 111
4-4-2. I-nstall
ation........ ................................................ .. ...................... .. .. . 111
CHAPTER 5. ELECTRICAL SYSTEM
5-1. Wiring diagram .......... ........................ . ....... ......... ..... . .......... ... ....... ............. .......... .......... ..... 113
5-2. Ignition c ircuit.. ........ .............. .. ......... . .. ........... . ..... . .. 114
5- 3. Ignition tim i ng adjustment ........... ...... ............ .......... ........ ........ .. ................. ........... .... .. ......... 121
5-4.
Lighting circuit.. .... .... ........ ...... ........ .... .. ............. .. . .... 124
CHAPTER 6. TROUBLE SHOOTING
Hard starting ............... ............
Poor
low speed engine operation ....... ..... ........... .. .......... ..
High speed operation problems ...... .......... ............. .......... ..... .. ..
Troubles
at both low and high speeds
....
12 5
.
.. 125
. .. 125
. 126

SOMMAIRE
CHAPITRE I. GENERALITES
1-1. Caracteristiques .......................... ....... ........................... .............. ......................... ......... ..... .... ... 2
1-2. Donnees d'entretien...................................
.......... ............................... .. ............ ............ ............. 4
1-3. Construction......................................................................................
....... ............................... 5
1-3-1 . Moteur...................... .......... ................................. ....... .............. .... .. ............................. 5
1-3 -2. Transmis si on de Ia puissance........... ............... . ....... .................................... .. .................. 12
1-3-3. Unite de commande............................... ......... .......................... ..................................... 14
1-3 -4. Systeme de direction...................................................................... .. .............................. 15
1-3-5. Chassis ................................................................ .. ...................................................... 15
1-3-6. Systeme electrique .................................. ............. .................... ........ .. ............................ 15
1-4. Outils ............................................................................................................................... ....... 22
CHAPITRE 2. MOTEUR
2- 1. Demontage du moteur..................................................... ...................... .................................... 27
2- 2. Demarreur manuel ............... . ............. .................................................................. ..................... 31
2-2 -1 . Depose.............................. .......... .. .............. .............. ........... .... ..... ............................... 32
2-2-2. Demontage ................................................................................................................... 32
2-2-3. Nettoyage et controle .................
........................ .............................. ............................. 33
2-2-4. Montage ........ ............ ......... ........ .................. .... ................. ......... ....... ........................... 33
2 -2- 5. Installation ............ ......... ........................ ....... ................................................. .............. 34
2-
3. Poulie primaire..... ......... ............................................................... .............. .. ............................ 35
2-3-1. Demontage .............................
..... ................................................................................. 36
2-3-2. Nettoyage et controle (Inspection) ...................
....... ...................... .. ................................. 37
2-3-3. Montage...................................................... .......... .. .......................... ........................... 38
2-4. Magneto avolant ................................................................................................... ...
..... .......... 39
2-4-1. Demontage . ....... ................................................................... .. ............. ......................... 40
2-4-2. Controle....... .. ...·........... ................ ..................................... ............... ............................ 4 I
2-4-3. Installation ........................................... ...... .... . .............. ............................................... 46
2-5. Carburateur .........
............ ................................. ........ ............................... .................. ..... ......... 47
2-5- 1.
2-5-2.
2-5-3.
2-5-4.
2-5-
5.
2-5-6.
Depose .
...... ........ ............ ...................... ........ ..................................................... .......... 47
Demontage .......................................
.......... ........................... . .... .. .............. .... ......... ..... 48
Nettoyage et inspection......
......... ............................................................... .. .................. 49
Montage................................................................................................. ...................... 50
Installation .......................... ................... ..... ........... .... . ...... .... ....................................... 5 l
Reglages......
....... ... ........... .............. ......... ............................................. ..... ................... 51
2-5-7. Rem placement du gicleur principal ............ ........ .. .............................. . .. ................... ........ 53
2-6. Pompe ahuile ............
......................... ...... ........... ......................... .. .... ......... .... ........................ 54
2-6-
1. Depose ......... ............. ................................................................................................. . 54
2-6-
2. Demontage ..... ............................................. ..... ................... ..... ...... .............................. 55
2-6-3. Nettoyage et inspection........................................................ ...
.. ..................................... 57
2-6-4. Montage....................
........ .................................................................. ......... ...·····.········ 58
2-6-5. Installation ............
................... . ............. .. .......... .......................................................... 58
2-
7. Moteur................................... .......... .............................................. ........ ........ .. ............... ........ 59
2-7-1 . Demontage ................................................... .. ...................... .. .................... .................. 62
2-7- 2. Nettoyage et inspection.... ........ ...................................................................... .. .............. 63
2-7-3. Montage ...................... .... ............................... ................... ............ ... ............................ 70
2- 8. Montage du moteur .......................................... ........................................ .. . .. ....................... .. .. 71

CHAPITRE 3. TRA IN D'ENTRAINEMENT
3-
I. Poulie secondaire..................................................... ....... .... .................................. .. .... .............. 75
3-1-1. Depose ...
.... ............................ ........... ......... ........ ..... ........... ...... ....... ...... ... ................... 76
3-1-
2. Nettoyage et inspection ...... ................... ........... ....... ........ .. ... . .. ....... ... ............................. 77
3-1 - 3. Montage..................... ..... ............ ........... .... ... .......... ... .................................................. 77
3
-1 -4. Installation ...................... ........ ............. ..... .... .... .......................................................... . 78
3-1-5. Reglages.... ................ ................................................................................................... 78
3- 2. Frein adisque.................... ....... ..... ............ ....................................... ..... ........... ... ........ ............ 8 I
3-
2- I. Depose ...... .......... .......... ............................................. .. .......... .. ................................... 82
3-2-2. Nettoyage et inspection...................................... ......................... ................................... 82
3-2-3. Installation .. .................. ................. ....... ................................... . ........... ...... .................. 83
3-2-4. Reglages.... ............... ................................................... ............... .. ....... ......................... 83
3- 3. Arbre avant ............................................................................................................................. 84
3-3-1.
3-3-2.
3-3-3.
3-3-4.
3-3-
5.
Depose ........... ...... ............................... ..... ... ..... ...... ...... ............. ........ .......................... 85
Demontage .........
........... . ....... ................. ..... ............ .. ................................................... 86
Nettoyage et inspection..
......... ............................................... .. ........... ....... .................... 86
Montage.........
.............. ................................... .. .............. .... .................. .. ................... .. 87
Installation ....................................................................................... ...
...... ................... 87
3-4. Arbre arriere....................... ...... ................................................................ ... ............................ 88
3-4-1. Depose
...... ................................... ........... ...... .. ...... ..... ...... ........................... .. .............. 89
3-4-2. Demontage ...........
....... .. ....... ........................ .... ....... .. ................ .. ..... ............................ 89
3-4-3. Nettoyage et inspection ......
..... ....................................................................................... 90
3-4-4. Montage................. ....... .............................................. ................................................. 91
3-4- 5. Installation ...... ........... . ......... .................. ..... .... .. ... ..... .................................................. . 91
3-5. Bogies ................ ............. .................. ......... .... ... .... ..... .. ...... ..................................................... 92
3-5- 1. Depose ........................................................................................................................ 93
3-5-2. Nettoyage et inspection .........
....... ............ ... ...... .. .... .............. .. ................... .................... 93
3-5
-3 . Installation ........................................ ......... ...... .. ..... ............ .. ....................................... 94
3-6. Chenille ..... ...... ... ........ ...................................................... .... ................. ....... ........................... 94
3-6-1.
3-6-
2.
3-6- 3.
3-6-4.
Depose ........................................
............ .. ... .. .. ....... ... ....... .. ...... .. .... ............................ 94
Nettoyage et inspection.....................
....... .... ... ............... ... .. ................ .... ............ ......... .. 94
Installation ................
...... ...................................................................... ... .................... 95
Reglage.......................
....... .................... ... ................................ .. ...... .. ......................... 95
3-
7. Boitier de chaine .... ........................................ ... ...... .. ...... ... ....... .............. ................................. 97
3-7-1. Depose ..................................................................... ....
.. .................. ... ........................ 98
3-7-2. Demontage .... ........... ........ ..... ...... ............ ................................. .. .................................. 98
3-7-
3. Nettoyage et inspection .................................... . .. ............................. .. ............................ 99
3-7-
4. Montage.... ........ ........................ ..... ......... ..................................................................... IOO
3-7-5. Installation ..................................................... ....... .............................. .. ....... ................100
3- 7- 6. Reg! age de Ia chaine .......................................................... ....... ....................................I 01
CHAPITRE 4. DIRECTION (SKI) ET CHASSIS
4- I. D.irection ......... ....... .......................................... ...... ........................... ...................... ...... ..........I03
4
-1 - I. Depose ................................................. ....... ........................................... ..................... 104
4-1- 2. Ncttoyage ct inspection ............................................................... .. ................................. 105
4-1-3. Installation ..................................... ... ........................................................................... 105
4-1-4. Reglage .................. ...... ........................................... .... ......... ................... ..................... 106
4-
2. Ski .... ..... ..... ...... ... ... .... .. ... ..... .. ....... ... .... . ... ........ ..... . ... .... .. .... ... . ... ..... .... ...... .. ... .. ...... ................ I07
4-2- 1. Depose ..... ......... . .......... ............ ............. ................................. .. ............. ..... ................. 108
4-2-2. Ncttoyage et inspection.............. ....... ......... ..... ......................... ... ............. ...................... 10 8
4-2-3. Installation .................................. ....... ..... .... . ...... ........................ .. ... ............................. 109
4-2-4. Reglage...
...... ................ ......... ........ .. ...... ...... . ..... ... ................ .. ................. .................... 10 9

4-3. Chassis et capot................................................. ...... ................................... ........ .... ........... ..... .II 0
4-3- 1. Depose ..... ........ .................................... .......... .... ............ .............................................110
4
-3 - 2. Installation ......... ..................... . .............. . ........... . ......................... . ........................ ....... 111
4-4. Siege ................................................................................................ ................ ....................... 111
4-4-1. Depose ..... ......................... ................. . ................. ...................... ................................ .II I
4-4-2. Installation ..................................
............... ........................... ...... ................................ .Ill
CHAPITRE 5. SYSTEME ELECTRIQUE
5-l. Scheme de ciiblage ............................. .......................... .. ........ .................................................. 113
5- 2. Circuit d'allumage................................................. ........... ............................... ... ....................... 114
5- 3. Reg! age de l'avance a l'allumage ........... ................... .......... ... .. . ..................... ............................. 121
5- 4. Circuit d'eclairage...................................... ............ . .... ............. ......... ... .... .................................124
CHAPITRE 6. DEPANNAGE
Demarrage difficile........................................... ....... ........ .............. ..................................... .. ....129
Fonctionnement du moteur afaible vitesse defectueux .............
.. ..... ......................... .....................129
Problemes de fonctionnement ahautes vitesses ..... ...... ...... ........................... ................................ 129
Prob1emes ahaute et faib1e vitesses ........................... ..... ............................. ......... . ................ .....130

GENERAl
GENERALITE
CHAPTER 1. GENERAL
1-1. Specifications
MODEL
GS338G
Dimen s ions :
Length
(w/ski s)
96 .1 in s. (2.440 mm.)
Width
33 .3 ins. (845 mm.)
Height (w/windshield)
38 .6 ins. (980 mm .)
Engine:
Type
Air-cooled 2-stroke 5-port
No. of cylinder 2
Bor e and stroke
2.362 x 2.346 in s. (60 x
59.6 mm.)
Displac ement
20 . 63 cu.in. (338 c.c.)
Max . horsepower 25 HP / 5.500 r.p.m.
Carbu
re tor KEIHIN CDX42-38 x 1
Lubrication system
"Autolub e" oil injection
Magneto output
Flywheel magneto 12V.-70W . @ 3.000 r.p.m.
Starting system: Recoil hand starter
Track and suspension:
Track
Molded rubber. steel reinforced
Width 15 ins. (380 mm.)
length on ground
39 ins. (990 mm )
Suspension
wheels 12 rubber wheels. bearing mounted
Drive sprocket Single polyurethane. 9 teeth
Wheel sprocket Single polyurethane. 9 te eth
Transmission:
Type
Aut oma tic centrifug al engagement. infinitely variable 3.5 : 1
~ 1 : 1
Drive
chain
Duplex roller chain enclosed in oil bath
Frame:
Type Fabricated steel
Cowl :
Type Reinforced fiberglass (removable)
Seat: Removable
Fuel tank:
Capacity
4.5 US gals. (17 .0 lits.)
Oil
tank capaci ty 2.4 qts. (2 25 lits.)
Front bumper:
Chromed tubular steel
Electrical:
Headl
ight
12V .- 60 / 60W High-low beam
Taillight
12V.-8W
Stoplight
12V .- 23W
Ig nition key switch
3- position . on dash
Brake:
Type Disc brake
Control
Handle lever. left-hand operated
Throttle :
Type
Handle lever. right - hand operated
Kill s wi t ch :
Type Push
button. right-hand operated
Accessories: Emergency starter rope. Service
tool kit
Optional equipment parts: Tachometer and speedometer
- 1 --

GENERAL GENERALITE
CHAPITRE I. GENERALITES
1-1. Caracteristiques
MODELE
GS338G
Dimensions et poids:
Longueur (sans skis)
2.440mm
Largeur 845 mm
Hauteur (sans pare-brise)
980mm
Moteur:
Type Deux-temps, refroidissement
par air, a5 lumieres
Nb. de cylindres 2
Alesage et course 60 x 59,6 mm
Cy lindree 338 cm3
Puissance maxi
25 ch. a5.500 tr/mn
Carburateur KEIHIN CDX42-38
X I
Graissage Systeme d'injection d'huile Autolube
Puissance du volant magnetique 12V-70W a3.000
tr/mn
Demarreur: Lanceur manuel areenroulement
---
Chenille et suspension:
Chenille Caoutchouc moule,
armature d'acier
Largeur chenille 380 mm
Longueur surface portante 990 mm
Suspension I2 galets caoutchouc montes sur roulements
Pignon d'entrainement I pignon en polyurethane (9 dents)
Pignon AR I pignon
en polyurethane (9 dents)
-Transmission:
Type Embrayage centrifuge automatique et variateur
(3,5/ I ~
1/1)
Entrainement Chaine arouleaux duplex baignant dans l'huile
Chassis:
Type Acier usine
-
Capot:
Type Plastique arme (amovible)
Selle: Banquette amovible
. -
Reservoir de carburant:
Capacite I7 litres
1- -Reservoir d'huile:
Capacite 2,25 litres
Pare-choc A
V:
Tube d'acier chrome
--
- --
Equipement electrique:
Phare 12V-60W
/60W Feux de route et de croisement
Feu AR 12V-8W
Feu stop 12V-
23W
Contact acle 3 positions (au tableau
debord)
Frein:
Type Frein adisque
Commande
Main gauche, levier au guidon
Accelerateur:
Commande
Main droite, levier au guidon
Commutateur d'arret d'urgence:
Commande
Par poussoir actionne par Ia main droite
Accessoires: Corde de lanceur de secours, trousse d'outillage
En option: Compte-tours et indicateur de vitesse
-
2-

1-2. Ser vice Data
MODEL
ENGINE
Cylin
der head tightening torque
Piston clearance
Lubrication oil
(R e commended oil)
Ignition timing
Compression ratio
Idling speed
Spark
plug (S.T.D.)
GENERAL
GS3 3 8G
Nut s: 16 .6 ~ 1 9.5 ft -lbs . (2.3 ~ 2.7 m-kgs.)
0.0018 ~ 0.0020 in. (0045 ~ 0.050 mm)
1st: YAMALU BE 2-stroke oil
2nd:
Another brand 2-stroke oil labeled
"B IA certified for service TC - W"
With dial gauge and point checker
B.T.D.C. 1 5±0 1 mm .
6.
58: 1
1 ,800 ±100 r.p.m.
1':-J .G.K. B- 7HS
GENERA LITE
1------------------ -! ----------------- - --------------
Carburetor:
Model
Mai n j et (S.T.D.)
Opt ional main jet
Pilot screw
S low jet (S.T.D.)
Partial jet (S.T.D.)
Fuel level
Valve seat
KEIHIN CDX42-38 x 1 (8 8400)
#14 0
#14 5 #1 35 #1 30
1-1/4
# 60
# 70
+0 .079. ( + 2 )
0.1 96 _0_
196
ln . 5 _ 5 mm .
0.07¢ in. (1.8¢ mm)
1 ------------------t-- -------- - ------------- - -------- ----
Oil pump:
Min im um stroke
Maximum stroke 0
.008 ~ 0.009 in. (0 20 ~ 0.25 mm)
0.06 ~ 0.0 7 in. (1 65 ~ 1.87 mm.)
1-- --------------- - -l ------------------ - ------- -- --
DRIVE:
Clut ch:
Primary spring
Secondary spring
V-belt
Sheave distance
Sheave
offset
Part No. 90501 - 45162 (Color code: Black)
Part No.
90508 - 35073 (Color code: Not painted)
Part
No . 820 - 17641-00
Outer line length:
10 63 ±0 07 ins.
02 + 0020.
. 4- 0.059 ln.
1.101±i3mm
(270±2 mm)
(
6.0 + 0 5 )
- 1.5 mm.
--
1-- ------------- --- -~- - ---- ------------
----·- -------- -
Chain housing:
Oil capacity
Oil
Reduction ratio (Drive chain
sprocket/Driven chain sprocket)
0.45 qt.oz. (430 c.c)
SAE 1 OW/30 motor oil "M S" detergent
12 / 23
1- ----------------+----- - -- - ---------- - --- --------- -
Suspension:
Track
deflection
0. 79 ~ 0. 98 in/22 l bs. (20 ~ 25 mm ./ 10 kg.)
Brake:
Brake pad
wear limit 0.04 in. (1.0 mm)
Gap between pad a nd disk
0. 008 ~ 0.04 in. (0 2 ~ 1.0 mm.)
BODY:
Ski
width (S.T D) 26.3 ins. (670 mm.)
Note:
The research and engineering departments of Yamaha are continual ly str iving to further perfect the GS338G Snowmobil e. Im -
provements and modific ations ar e therefore inevitable. Inform a tion regarding changes will be forwarded to all Authorized Ya-
maha Sno wm obile Dealers as soon as it is available.
- 3 -

GENERAL
1- 2. Donnees d'entretien
MODELE
MOTEUR:
Couple de serrage de
Ia culasse
Jeu du piston
Huile de graissage (recommandee)
Calage de l'allumage
Rapport volumetrique
Regime de ralenti
Bougie (S.T.D.)
Carburateur
Modele
Gicleur principal (d'origine)
Gicleurs principaux en option
Vis de ralenti
Gicleur de ralenti (d'origine)
Gicleur partie) (d'origine)
Niveau d'essence
Siege de pointeau
GENERALITE
Ecrous: 2,3 ~ 2,7 m-kg
0,045 ~ 0,050 mm
1. Huile deux-temps Yamalube
GS338G
2. Autre marque d'huile repondant aux prescriptions BIA
pour service
TC- W
Avec Jauge acadran et controleur de vis platinee
1,5±0,1
mm AV. P.M.H.
6,58: 1
1.800±100 t/min
N.G .K. B-7HS
KEIHIN CDX42-38 x I (88400)
#140
#145, 135 et 130
1-
1/4
#60
#70
+2
5_
5mm
¢1 ,8 mm
~---- -- ------ ---------------------+------------------------------------------------------ -----------
Pompe ahuile
Course minimum
Course maximum 0,20
~ 0, 25 mm
1,65
~ 1,87 mm
~ ------------------------------ +- ~----~-------------------------------------------- ·---·--
TRANSMISSION:
Poulies:
Ressort de poulie primaire
Ressort de poulie secondaire
Courroie trapezoidale
Distance entre poulies:
Decalage des poulies:
Piece No. 90501-45162, Couleur de til: Noir
Piece No. 90508-35073, Couleur de til : Non colore
Piece No. 820-17641- 00
Longueur de circonference ext: 1, 108±8 mm
270±2 mm
+0,5
6,0 -),
5 mm
~ ------------------------------~--------------------------------·---------------------------
Carterde chaine:
Contenance d'huile
Huile
Taux de reduction (Pinion
menant/pinion mene de chaine)
Suspension:
Fleche de Ia chenille:
Frein:
Limite d'usure des plaquettes
de frein
Jeu plaquette-disque
CHASSIS:
Ecartement des skis (d'origine)
Remarque :
430 cc (0,45 oz.)
Huile moteur detergeante SAE 10W/30W
"MS"
12/23
20 ~ 25 mm/10 kg
1,0mm
0,2 ~ 1,0 mm
670mm
Les departements de recherche et d'etude de Yamaha s'efforcent d'ameliorer sans cesse Ie motoneige GS338G. Par consequent, des
modifications sont done inevitables. Tous
Ies concessionnaires Motoneiges Yamaha seront avises des que possible de toutes modifica-
tions ou alterations.
- 4 -

GENERAL
2. Operatio n
As
the pi ston moves upward, the pre ssure in the
crankc ase drop s below atmospheric pressure. and the
mixture is dra wn into the crankcase from the car -
buretor . As the piston moves downward , the piston
seals off all parts and compresses crankcase volume un -
til
it is above atmo sp her ic pressure.
During engine operation, alternating positive and
negative pressure pulses are caused in the crankcase
and carried through the impulse port to the fuel pump
drive chamber. This causes the fuel pump diaphragm to
vibrate up and do w n. The up and dow n pump
diaphragm action sucks fuel out from .the fuel tank.
through the outlet. check valve. and inlet control valve,
then to the regulator chamber.
The main diaphragm is forced downward by the inl et
tension spring through the inlet control lever. At the
same time. it is forced upward by the diaphragm spring.
But it is
so designed that th e upward force is greater
than the downward force.
The in let control valve is usually separated from the
valve seat. But when fuel flows into the regulator
ch amber . the fuel weight and pressure in the chamber
rises. This rising pressure forces the main diaphragm
downwa rd against the force of the diaphragm spring.
As the main diaphragm is forced downward, it ca us es
the inlet control l ever to close the inlet control valve,
and thus the fuel stops flowing in. (That is, it also
prevents the pressure inside the regulator chamber from
rising.) In
this manner. a constant regulator chamber
pressure is maintained .
This
chamber pressure is variab le. An adjusting screw
is located in the bottom of the carburetor. If this screw
is turned in, it pushes more firmly against the diaphragm
spring.
This
results in more pressure through the carburetor
before the fuel valve is shut off. If the screw is backed -
out. the diaphragm spring relaxes. It then takes less
fuel pressure to shut off the fuel valve.
The amo unt of fuel pressure is registered in a fuel level
tube attached to the outside of the carburetor. Fuel
level
height will rise and fall with the level tube as the
adjustment screw is screwed in and out.
Onc e th e fuel level has been stabilized by adjustment,
then there are two adjustments to contro l fue l to the
car buretor venturi. The fuel (under constant pressure) is
metered by the slow adjusting screw or by the main ad -
justing screw, it is discharged through the idle discharge
chamber port and the main discharge port into the ven-
turi.
As this fuel enters the carburetor venturi, it is broken up,
vaporized
and ca rri ed al ong by the air rushing in to the
crankcase .
-11 -
GENERA LITE
2. Fonctionnement
Lorsque
le piston se deplace vers le haut, Ia pression dans le
carter descend sous
Ia pression atmospherique, et le me-
lange est attire dans le carter du carburateur. Lorsq ue le
piston se deplace ve rs le bas, les segments de celui-ci per-
mettent
Ia compression du volume du carter jusqu'a ce qu'il
so it au-dessus de Ia pression atmospherique.
Durant le fonctionnement du moteur, des impulsions de
pression negatives et positives alternativement
ont lieu dans
le carter et sont acheminees par l'intermediaire de !'orifice
d' impulsion a Ia chambre de commande de Ia pompe a es-
sence. Ainsi
Ia membrane de Ia pompe a essence vibre vers
le haut et le bas. Cette action de
Ia membrane permet !'as-
piration de !'essence a partir du reservoir d'essence,
par l'in-
termediaire du clapet de retenue et de
Ia soupape de com -
mande d'admission a
Ia chambre de regulation.
La membrane principale est forcee vers le bas
par le ressort
d'adm ission par l'intermediaire du levier de commande
d'admission. Au meme moment il est force vers le haut par
le ressort de Ia membrane. Mais sa conception est telle que
Ia force vers le haut est plus grande que Ia force ve rs le bas.
La soupape de commande d'admission est generalement se-
paree du siege de
Ia soupape. Mais lorsque !'essence s'e-
coule dans Ia chambre de regulation, le poids de !'essence et
Ia pression dans Ia chambre aug mentent. Cet te augmenta-
tion de pression force Ia membrane vers
le bas contre Ia
force du ressort de
Ia .membrane. Lorsque Ia membrane
principale est forcee vers
le bas, le levier de commande
d'admission ferme
Ia soupape de commande d 'ad mission, et
par suite !'essence ne penetre plus a l'interieur (c'est a dire
auss
i, empeche !'au gmentation de Ia pression a l'interieur de
Ia chambre de regulation). De cette fa<;:on, une pression
constante
dans Ia chambre de regulation est maintenue.
La pression de cette chambre est variable. U
ne vis de re-
glage e st situee a Ia partie inferieure du ca rburateur. Si
cette vis est vissee, elle pousse plus fermement contre le res-
sort de Ia membrane.
II en resulte plus de pression a l'interieur du carb urateur
ava nt que Ia soupape d'adm ission de !'essence so it fermee.
Si Ia vis est devissee, le ressort de membrane se relache. il
faut done moins de pression d'essence pour fermer Ia sou-
pape d'essence.
La
qu antite de pression d'essence est enregistree dans un
tube de niveau d'essence fixe al'exterieur du carburateur.
Le niveau d'essence variera done avec le niveau du tube
lorsque
Ia v is de reglage sera vissee et devissee.
Lorsque le niveau de !'essence est stabilise par reglage, deux
reglages
pour commander !'essence au venturi du carbura -
teur doivent etre effectues. L'essence (sous pressi
on cons-
tante) est mesuree
par Ia vis de reglage lent ou par Ia vis de
n!gla ge principal, iJ est libere par !'orifice de liberation de Ia
chambre et par !'orifice de liberation principal dans le ven-
tur
i.
Lorsque !'essence entre dan s le venturi du carburateur, elle
est pulverisee, vaporisee et transmise par I'air dans le carter.

GENERAL
1 -3 - 2. Power transmission
Engine power is transmitted to the drive track in the follow-
ing
manner:
0 The primary sheave mounts directly to the engine
crankshaft. It transm its power to the secondary sheave
through the V-belt.
0 The secondary sheave unit and chaincase drive sprocket
are mounted on the same shaft. Power pa sses from the
secondary sheave. through the drive sprocket. then
down through a chain to the driven sprocket mounted
on the front axle.
0 As the front axle turns. it rotates a single attached
sprocket. The sprocket meshes with. and turn s. the
track.
1. Primary
sheave
As the engine speed increases. the weights loc ated in -
side the primary sheave cap are thrown outward by cen-
trifugal force. overcoming the primary spr ing force. This
causes the primary sliding sheave to be pushed toward
the primary fixed sheave.
As a resu lt. the V- belt is gripped between the sliding
sheave and the fixed sheave. Engine power is now be-
ing transmitted to the drive track through the complete
drive system. The V-belt begins turning at about 2,600
~ 2.700 r.p.m.
As engine speed increases. the sliding sheave moves
further toward the fixed s heave and squeezes out the V-
belt radially. Since the l ength of the V- belt rem ains
constant. the V-belt on the side of the secondary sheave
is pulled by the primary sheave and forced to move
toward the shaft. This causes the ratio of the primary
sheave diameter to secondary sheave diameter to
change; that is. the reduction ratio is automatically
changed according to the load and speed of the engine.
To sum up, the reduction ratio between the crankshaft
and the secondary sheave varies from 3.5 : 1 to 1 1.
2. S econdary sheave
This secondary sheave operates in the following
manner:
a. When at rest or at slow speed (and high track load), the
secon dary sliding sheave is forced against fixed sheave
by the secondary spr ing.
b.
As engine rpm increases. and primary sheaves are forc-
ed together. the V-belt is pulled down closer to the
center of the secondary sheaves.
The V- belt wedges the two secondary sheaves apart. In
other words. the diameter of the circle formed by the V-
belt on the primary sheave becomes l arger. while the
diameter on the secondary sh ea ve becomes smaller .
- 12 -
GENERALITE
1-3-2. Transmission de
Ia puissance
La puissance du moteur est transmise a Ia piste d'entrainement
de
Ia fac;:on suivante:
0 La puolie primaire est couplee directement au vilebrequin.
Elle transmet Ia puissance a
Ia poulie secondaire par l'in-
termediaire d'une courroie en
V.
0 L'unite de poulie secondaire et le pignon de commande de
Ia chaine sont montes sur
le meme arbre . La puissance est
transmise de Ia poulie secondaire
par l'intermediaire du pig-
non de
commande de chaine, puis par l'intermediaire de Ia
chaine
au pignon de chaine commande monte sur !'axe
avant.
0 Lorsque !'axe avant tourne, il assure Ia rotation d'un pignon
de chaine. Le pignon s'engrene et permet le mouvement des
chenilles.
I. Poulie primaire
Lorsque
Ia vitcsse de rotation du moteur augmente, les
poids situes al'interieur du couvercle de
Ia poulie primaire
sont projetes vers l'exterieur
par Ia force centrifuge, neutra-
lisant
Ia force du ressort primaire. Par suite Ia poulie mo -
bile primaire est poussee vers Ia poulie fixe primaire.
D'au -
tre part,
Ia courroie en V est serree entre Ia poulie mobile et
Ia poulie fixe. La puissance du moteur est maintenant
transmise aux chenilles
par l'intermediaire du systeme de
commande complet. La courroie en V commence atourner
aenviron 2.600 ~ 2.700 tpm.
Lorsq
ue Ia vitesse de rotation du moteur augmente, Ia pou-
l
ie mobile se deplace vers Ia poulie fixe et serre Ia courroie
en
V, de fac;:on radiale. La longueur de Ia courroie etant
cons tante, celle-ci du cote de Ia poulie secondaire est tiree
par Ia poulie primaire et obligee de se deplacer vers !'axe.
Par suite le rapport entre le diametre de Ia poulie primaire et
le diametre de Ia poulie secondaire change; c'est adire que
le rapport de reduction est automatiquement modifie en
fonction de
Ia charge et de Ia vitesse du moteur.
Pour resumer, le rapport de reduction entre le vilebrequin et
Ia pou lie secondaire varie de 3,5 : I a I : I.
2. Poulie secondaire
Cette poulie fonctionne de Ia fac;:on suivante:
a.
Au repos ou afaible vitesse (et forte charge), Ia po ulie se-
condaire mobile est appliquee contre
Ia poulie fixe par le
ressort secondaire.
b. Lorsque
Ia rotation (tpm) du moteur augmente, et que les
poulies primaires
sont pressees ensembles, Ia courroie en V
est tiree vers
le bas vers le centre des poulies secondaires.
La courroie en V maintient les deux poulies secondaires se-
parees. En d'autres termes, le diametre du cercle forme par
Ia courroie en V sur Ia poulie primaire devient plus grand,
tandis que Ie diametre sur Ia pou lie secondaire de vient plus
petit.