Yamaha GP 338F Building instructions

VA AHA ' .. ..
, .
, .. 8101108111
GP 338F / GPK433F
. SIRVICIMAIUAI
~

TABLE OF CONTENTS
CHAPTER 1. GENERAL ....... .... ... . ......... ...... . ....... ...... ..
1 -1 . Specifications ..............
.. .. . .. .............. .... ............. .. .. .. . .. .. .... .. . ... ........... ... .................. .. . ..
1-2. Service Data
1-3. Tools .........
CHAPTER 2. ENGINE
2-1 .
2-2. Removing the
Engine.
Starter .....
2-2-1. Removal
2-3. Primary Sheave .......... ..........
2-3-1. Disassembly.
2-3-2. Cleaning and Inspection .. ................. .. .. .
2-3-3 . Assembly
5
5
6
7
7
.. ...... .. ..... 8
9
9
2-4 . C.D.I. Magneto .................. 11
2-4-1. Removal .............. ........ ........... .. ............ .. ........... .. . .. . .. .. .. . .. ..... .. ......... .. ... .. .. .. ........... 12
2-5. Carburetor ........... ............... 14
2-5-1. Removal.
2-5-2. Disassembly (GPX338F)
2-5-3. Cleaning and Inspection (GPX338F) ........................ .. ............ .. .. . .. . .. ........ .. . .. . .. ..... ..
15
16
17
18
18
18
2-5-4. Assembly (GPX338F) ... ...............
2-5-5. Installation (GPX338F)
2-5-6. Adjustments (GPX338F) .
2-5-7. Disassembly (GPX433F) .... 20
2-5-8. Cleaning and Inspection (GPX433F) ..... .. .......... .......... .. .. .. ... 20
2-5-9. Assembly (GPX433F) .... ........ . ....... .... ... .. .... .. . .. . .. .. .. . .. ....... .. .... .. ............... .. . .. .... 21
2- 5-10. Installation (GPX433F)
2-5-11. Adjustments (GPX433F).
2-5-12. Carburetor with Accelerator Pump (GPX433F)
..... 21
.
.. 21
... 23
2-6. Oil Pump ........................ .. ...... .. . .. ........ .. .. ...... .. . .. ... 24
2-7 . Engine .....
2-7-1. Disassembly ........... .. .. .
CHAPTER 3. POWER TRAIN
3-1. Secondary Sheave .................
.. . .. .
3-1-1. Removal
3-1-2.
3-1-3.
3-1-4.
Cleaning and Inspection.
Assembly ..
Adjustments ...... .......
3-2. Disc Brake ................
3-2-1.
3-2-2.
3-2-3.
3-2-4.
Removal ....
Cleaning and Inspection
Installation
Adjustments
3-3. Chain Housing ............ .. ....... ..
3-3-1 .
3-3-2.
3-3-3.
Removal
Cleaning and Inspection
Assembly
..
.. .. .. .. .. . ...... . 26
.. .. ..... .. .. ................................................... 26
... 29
...29
30
30
.. .. .... .. ...... .... .... ... 30
.. .. .. . .. . .. ..... ....... 33
. ........... ............... 35
..." ............. .. .... 36
...36
.... 36
.... 37
. .. .. .... ............. ... ........... .. ............ ... 38
.... 39
. ... 39
. .. 40

Front Axle
Rear Ax l e.
........ .. . .. .. ......... .. . .. .. .. ... .. .. ...... .. ...... .. .. . 41
......
.. . .. .. .. . ... . .. .. .. . .. .. .. ..... .......... .. . ....... 42
3-4.
3-5 .
3-6. Sliding Suspension .........
.. ... .. .. ...... .. .............. .... .... .. .. ........ .. ...... .. ..... .. ...... .. ... .. .. . .. ........ .. . 43
CHAPTER 4. STEERING (SKI) AND CHASSIS . .. . ... .. ... . ...... . .. ....... .. . ... .. . .. . .. . .. . ... .. ..... 45
4-1 . Frame ............. .. .. .. .. .. ..... ...... .. ...... .. . ..... . .. ... .. . ... . ... .. .. .. ... .. .... ... .. .... .. .. ....... .. .. .. .... .. ..... .. ... 46
4-2. Engine Mount .....
.. ...... . .. .. ... .... .. .
4-3. Oil and Fuel...... .. .. . .. ......... .. .............
4-4. Ski .
.. ........... ....... .. .. .. .. ...
Steering ..............
Control Wires
.... 48
.
.. ..... .. .... .. . .. .................. .. .. .. .... .. .. .. ...... .. 48
....... .. ...... .. ............. .. .... .. .. .. ............ .. 48
.....
48
... 48
4-5.
4-6.
4-7. Shroud
.. ..... ... ............. .. ........... .. .... .. .... .. .. ...... .. ......... .. .. ....... .. . .. ... .. ........ .. .. .. .. .. . .. ...... .. ......... 48
CHAPTER 5. ELECTRICAL SYSTEM
.. .. ........ .. ... ..... .. ...... . .. . .. .. .. ..... 49
CHAPTER 6.
TIGHTENING TORQUE . ... .... .. . .. ................. .. .. .. .. .. .. .. .... .. .. ... .... .. .. ... .. .. 57

GENERAL -Specifications, Service Data
CHAPTER 1. GENERAL
1 -1 . Specifications
Model
GPX338F GPX433F
Dimensions & Weight:
Overall length (including the ski)
98.8 ins. (2,510 mm.) 98.8 ins. (2,510 mm.)
Overall width
39 .8 ins. (1,010 mm.)
39.8 ins. (1 , 010 mm.)
Overall height (including the windshield) 38.0 ins. (965 mm.)
38.0 ins. (965 mm.)
Engine:
Type
Two-stroke five-port induction
Two-stroke five-port induction
aluminum cylinder
aluminum cylinder
No. of cylinders & arrangement Parallel
twin Parallel twin
Displacement
20.62 cu.in. (338 c.c.)
26.42 cu.in. (433 c.c.)
Bore & stroke
2.362 x 2.346 ins. (60 x 59.6 mm.)
2.677 x 2.346 ins. (68 x 59 .6 mm.)
Cooling system Natural air cooled Natural air cooled
Lubrication system
"Autolube" oil injection
"Autolube " oil injection
Oil tank capacity
2.4 qts. (2.25 lits.) 2.4 qts. (2.25 lits.)
Starting System: Recoiled hand starter Recoiled hand starter
Fuel System:
Fuel Gasoline (high-octane) Gasoline (high-octane)
Fuel
tank capacity
6.0 US.gal. (23.0 lits.) 6.0 US.gal. (23.0 lits.)
Carburetor Diaphragm type Diaphragm type
MIKUNI BN38-34SH x 2 KEIHIN
CDX42-38 x 2
Ignition and Electrical Systems:
Ignition system Flywheel
magneto (CD I)
Flywheel magneto (CDI)
Headlight 12V.
60 / 60W. (High/ Low beams) 12V.
60/60W. (High/Low beams)
Taillight
12V . 8W.
12V.8W.
Stoplight
12V.23W.
12V.23W.
Meter lamp
12V . 3W.
12V . 3W.
Frame: Fabricated
aluminum and steel Fabricated
aluminum and steel
Drive track:
Molded rubber, steel reinforced
Molded rubber, steel reinforced
with cleats
with cleats
Transmission:
V-belt automatic transmission
V-belt automatic transmission
Brake: Disc brake Disc brake
1 -2. Service Data
Model
GPX338F GPX433F
Engine:
Cylinder head tightening torque Nuts:
16 .6 - 19 .5 ft-Ibs.
Nuts : 16.6 - 19.5 ft-Ibs .
(2.3 - 2.7 m-kgs.) (2.3 -
2.7 m-kgs.)
Bolts :
14.5 - 16.6 ft -Ibs. Bolts: 14 .5 - 16 .6 ft-Ibs.
(2.0 - 2.3 m-kgs.)
(2.0 - 2.3 m-kgs.)
Piston clearance
0.0018 - 0.0020 in.
0.0018 - 0.0020 in.
(0045 - 0.050 mm.) (0.045 - 0.050 mm.)
Lubrication oil
Yamalube or Johnson outboard oil
Yamalube or Johnson outboard oil
Ignition timing
B.T.D.C. 1.6±0.1 mm.
BTD.C . 1. 6±0.1 mm.
-1-

GENERAL -Service Data, Tools
Model
Compression ratio
Idling speed
Spark plug
Carburetor:
Model
Number of turns out
Main adjuster
Slow adjuster
P.J.
S.J.
Fuel level
Valve seat
Ski width
Drive track deflection
Oil pump
Note:
Minimum stroke
Maximum stroke
GPX338F
7.8 : 1
2,100 r.p.m.
N.G.K. B-9EV
MIKUNI BN38-34SH x 2 (87800)
L. R: 1±' 1/8
L. R: 3/4
#8 5 (Spare #95)
0.059 in. dia. (15 mm¢)
29.5 ins. (750 mm.)
0.69 -0.71 in. (17. 5±5 mm.)
0.20 - 0.25 mm.
1.60 - 1.78 mm.
#95 pilot jet should be used when the engine speed
acceleration is
not smooth at temperatures below
0° C at low altitudes.
1-3 _ Tools
To service the snowmobile , the following tools are re-
quired.
o Special tools
o Gauges (Measuring instruments )
1. Special Tools
2-b.
o General tools
o Standard tools
GPX433F
7.0: 1
2,500 r.p.m.
Champion N-2G
KEIHIN CDX42-38 x 2 (87900)
L. R:
L, R:
#65
#45
1±118
1-3 /8
0.059 in. dia. (1 .5 mm ¢ )
29.5 ins. (750 mm.)
0.69 -0.71 in. (17.5±5 mm.)
0.20 - 0.25 mm .
1.60 - 1.78 mm .
1-a. Crankshaft separator
1-b . Crankshaft jig 1-f.
Wedge
2- c. Magnet puller attachment
5. Sheave
gauge
1-c. Press bo x
1-d. Press
pin
1-g . Stop (56 mm .)
2-a.
Magnet puller body
2-b . Magnet puller screw
2-d .
3.
4.
Fig. 1- 1
- 2 -
Screw , 8-mm. L : 80 mm . 6. Primary fixed sheave puller bolt
Dial gauge stand #2
7-a. Primary sheave
inst a ller / remo ver 2
Sock
et end wrench
7-b.
Primary sheave installer/remover 1