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I
Yamaha
ENGINES
'
YAMAHA
1975 AND EARLIER
338,396 AND 433cc
TWO CYLINDER MODELS
CONDENSED SERVICE DATA
338,
396,
433
Engine Model
810
811,813
818
8ore-{mm)
.
60
65
68
Inches
.
2.36
2.56
2.68
Stroke-{mm)
.
59
.6
59
.6
59
.6
Inches
.
2.35
2.35
2.35
No.
ofCylinders
.
2
2
2
Displacement-{cc)
.
338
396
433
Cubic Inches
.
20.6
24.1
26.4
Horsepower
@
RPM:
SL,SW
,EW
..
24@5
500
28
@5500
30@5500
SS,GP
..
32
@6500
36@6000
40@6500
Cooling Type
.
Cent. Fan
Cent
.
Fan
Cent.
Fan
Carburetor Model
.
Keihin
Keihin
or
Mikuni
Diaphragm
Diaphr agm
Number Used
.
lor
2
lor
2
•
v
.
2
Ignition:
Type
.
Ener
gy
Tra
nste
r
agneto
Point Gap
.
See1'ext.
ext
See Text
Timing Advance?
.
No
No
No
Timing 8TDC
.
Sf-
~
.\
t
See
Text
See Text
, ,
'
t
Spark
Plug:'
SL,SW,EW .
.
NGK
NGK
NGK
87HZ
87HZ
87HZ
\
.
SS, GP
NGK
NGK
Champion
,
.
89H
87HZ
N2G
F
,
.
I
rude Gap (mm)
.
.
0.5-0
.6
0.5-0.6
0.5-0.6
'
nch
.
0.020-0.024 0.020
-0.0
24 0.020-0.024
..
,lV"Oil
Ratio
.
20
:1*
20
:1*
Autolube
*
If, not equipped
with "Autolube".
MAINTENANCE
Data for recommended plug for normal
SPARK PLUGS. Selection of spark
use. Excessively cold weather and/or
plugs will depend upon type of service
,
light load conditions may require spark
ambient temperature
a
nd horsepower
plugs of warmer heat range. Hard
of engine. Refer to
'Condensed
Service
usage,
heavy
loads,
warm weather and
higher horsepower may require spark
plugs of colder he
at
range
:
CARBURETORS. Various carbure
tors have been used. Refer to the appro
pri
ate
carburetor
paragraphs
in FUN
DAMENTALS section for carburetor
se
rvice
.
For
adjustment
of carburetors
and "Autolube" refer to the appropriate
following
paragraphs.
ONE (KEIHIN OR MIKUNI DIA
PHRAGM)
CARBURETOR. The car
buretor is installed on a
"Y"
type inlet
manifold and provides the fuel-air
mix
ture to both
cylinders.
Initial fuel-air
mixture setting is as
follows:
SL338 (Keih in )
Idle mixture needle
.
.
.
1
Va
turns out
High speed
mixture needle ..
.. .
1
V
4 turns out
Fuel level (F- Fig.
1A)
.
.. ..
39 mm
Inlet lever height
(H-Fig.
1A)
5.7
mm
C. Clearance
N.
Nula
M.
Mark
T.
Throttl e
shan
288
Fig. 1-Vlew showing checking and adJuslmenl
polnls
fOI
synchlon/z;ng
carburelor opening 10
"
Aulolube" 011 InJecl/on. Pump Is I//Ied from
nOlmal position
to
better show the mark
.
Refer
to
text
for ltie Iwo
melhods
of checkIng
adJuslment.
.
SW396 (Mik uni l-c-
Idle mixture needle
..
.
1
1
4
turns
out
High speed
mixture needle
.
.
. . .
1
%
turns out
SW433,
RW
433
(Mik uni) -
Idt
uu
xt
ure needle
.
. . 1
Va turns out
I
igh
speed
mixture needle
.
..
.
.
1
V2
turns
out
On all models with one
carburetor.
linkage adjustment is limited to syn
chronizing the
"Autolube"
oil
injection
to the carburetor throttle. With
t~
carburetor throttle completely
open
(maximum speed) and the pump con
trol rod pulled
to
maximum position.
clearance (C- Fig. 1) should be 1-1.5
mrn
(0
.04-0 .06
inch). Clearance
is
measured between lower
adj
usting nut
and lever on carburetor. Adjustment
is
accomplished by turning nuts to
obtain
correct clearance.The top nut locks the
position onower nut.
Another method is to open throttle
completely and check to see ifoil pump
end of rod is aligned with mark (M). If
not relocate nuts (N). It will usually be
~
'f
fl// 1110"~
Fig. 1A - Dlew/ng of Kelhln d/ephlllgm c"butt
tOI.
Refel to text
fOI distance (F)
between
c.nl.
of clllbuletol bOil and fuel
Ilne/.
Height (HI 01
fuel Inlet
needle
Is listed In
text. Refe' to
FU,.
DAMENTALS
section
fOI method of adJustmtllt
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