Yamaha 396 Service manual

Yamaha ENGINES
YAMAHA
1976
AND LATER
E338, SS338 AN D SS433 TWO
CYLINDER MODELS
CONDENSED SERVICE DATA
Engine Model E338 88338 88433
Bore-(mm). .
.. . . ... . . . .. . . . ....
60 60 68
Inches ...................... 2.362 2.362 2.677
Str oke-(mm) .... . .. ... .. . . ... . . 59.6 59.6 59.6
Inches ..
........ ... . .... .... 2.346 2.340 2.346
No. of Cylinders
.. . . ... .... . ....
2 2 2
Displacement-co . . .. . . . . . .. . . . . . 338 338 433
CubicInches .........
... .... . 20
I).
20.63 26.4
CoolingType .
... . .. . ... ........ Free Air" Free Air Free Air"
Carburetor Model
.... . . .. . .. . Mikuni (B) Keihin (PW) Keihin
(PW)"
Number Used .... ..... , ...... 1 1 1
Ignition:
Type
.. . .. ..
,........ cm cm cm
Timing BT,_(' .............. 1.5-1.7 mm
1.6mm 1.6mm
Spark P'
, Li ........................
BR9EV""
BR9EV
BR9EV""
·1· Electrode Gap(mm) .
....... . 0.5-0.6t 0.5-0.6 0.5-0.6
Inch . . . . .
.... . . . .. .. . .. . 0.020-0.024t 0.020-0.024 0.020-0.024
Fuel/OilRatio
.... ... ..... . . .. . . Autolube Autolube Autolube
"Modelsprior to 1980use Free Air cooling. All198
0-1981 models are equipped with
Axial Fan.
""Engine models prior to 1978 use Keihin (PW) model carburetors. All 1978-1981
models use Keihin (BD) model carburetors.
"""Models prior to 1980 use BR9EV. All 1980-1981 models use BR9ES.
tModels prior to 1979 use 0.5-0.6 mm (0.020-0.024 inch) electrode gap. All
1979-1981 models use 0.7-0.8 mm (0.028-0.031 inch) electrode gap.
on E338 models, 2,000 rpm on S8338 Model Number
MAINTENANCE models and 1,500rpm on 88433 models.
Initial fuel/air mixture setting is as 1976
8PARK PLUG. Selection of spark follows: SS338 155
plug will depend upon type of service SS433 155
and ambient temperature. Standard Model Turns Out
plug is given in Condensed Service Data 1977
table. Excessively cold weather and/or 1976-1977 8S338 150
light load conditions may require spark 88338 1 8S433 150
plugs of warmer heat range. Hard 88433 P/4
usage, heavy loads and warm weather 1978
may require spark plugs of colder heat 1978 S8338 140
range. SS338 P/8 8S433 152
8S433
P/ 2 E338 220
CARBURETOR. A Keihin (PW) type
carburetor is used on S8 models prior to 1979-1981 1979-1981
1978 and a Keihin (BD)type carburetor 88433 16/8 8S433 145
is used on 1978-1981 SS models. A E338 240
Mikuni (B) type carburetor is used on 1978-1981
E338 models. Carburetor is installed on E338 1
If carburetor is removed for overhaul ,
a "Y" type intake manifold and provides refer to LUBRICATION section for
syn -
the fuel/air mixture to both cylinders. Standard carburetor main
jet is as chronizing Autolube pump to throttle
Standard idle speed setting is 1,700 rpm follows: opening.
294

I
Yamaha
ENGINES '
YAMAHA
1975 AND EARLIER
338,396
AND 433cc
TWO CYLINDER MODELS
CONDENSED SERVICE DATA
338, 396, 433
Engine Model 810
811,81 3 818
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
Displacem
ent-{ cc) .
338 396 433
CubicInches . 20.6 24.1 26.4
Horsepower @ RPM:
SL,SW,EW .. 24@5500 28 @5500 30@5500
SS
,GP .. 32
@650 0 36@6000 40@6500
Cooling Type . Cent. Fan Cent. Fan Cent. Fan
Carburetor Model . Keihin Keihin or Mikuni
Diaphragm Diaphragm
Number Used .
lor 2 lor 2 • v. 2
Ignition:
Type . EnergyTranster agneto
Point Gap . See1'ex
t. ext SeeText
Timing Advance? . No No No
Timing 8TDC . Sf-
~ .\ t See Text
SeeText
,, '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 0.020-0.024 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 and horsepower plugs of warmer heat range. Hard
of engine. Refer to ' Conden sed Service us
age, 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 paragr aphs in FUN-
DAMENTALS section for carburetor
service. For adju stment 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 (Keihin)-
Idle
mixture needle . . . 1 Va turns out
High speed
mixture needle .. .. . 1V4 turns out
Fuel level (F- Fig. 1A) . .. .. 39 mm
Inlet lever height
(H-Fig . 1A) 5.7 mm
C. Cle arance
N. Nul a
M.
Mark
T. Throttle 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 (Mikunil-c-
Idle
mixture needle .. . 11 4 turns ou t
High speed
mixture needle . . . . . 1% turns o ut
SW433, RW433 (Mikuni)-
Idt uu xture needle . . . 1 Va turn s ou t
I igh speed
mixture needle . .. . . 1 V2 turns ou t
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 ope n
(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 obta in
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 / / 1 1 1 0" ~
Fig. 1A-Dlew/ng of Kelhln d/ephlllgm c"butt
tOI. Refel to text fOIdistance (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

ERTER
st be remembered that the
lit is centrifug ally controlled
Iriven
unit responds , therefore
.ion and belt face width have a
.aring on
alignment of sheave
re. Two sheaves which are in
a lig n men t
with correct belt
will move out of alignment if
omes too
tight or too loose. Belt
ar or a belt of incorrect width
) c ha nge alignment and tension
ough shaft center distance and
re as specified.
lost models,
the drive belt can be
ed
with a minimum of disas-
by pulling the belt into bottom
ve of driven pulley then slipping
ff drive pulley. Installation is
~ of rein oval procedure.
-n b elt is removed and/or unit is
' ~ m b l e d , inspect all components
SPEED TUNING
GENERAL
, torque converter unit is involved
.Y speed tuning decision for two
ns; re
sults and safety.
ere is littl e point in spending time
noney modifying and fine-tuning
ngine unles s the drive trai n is
)!e of making the best use of i,he
'power gained. The degree of mod-
lion
of the converter drive and
.n units is so inter-related that an
.t procedure cannot be outlined.
, section, therefore , will attempt to
mly the principles which apply and
precautions to be observed.
he
high engine speeds associated
h performance tuning makes it
-erative that care be used in main-
ling th e balance and trueness of
lch
components . Racing drive
ches should be equipped with a
tter
sh ield.
;peed
tuning the converter unit gen-
lly involves
rai s ing the eng agement
-ed, extra attention to dynamic bal-
ce of
the total unit, careful belt selec-
n,
and combating down-shift lag of
iven member . The final step in con-
rt
er tuning is mating the drive unit,
It and driven unit into a carefully
.lanced package which will tran sm it
Igine power to the track in its most
fective form .
Although
the principles of perform-
nee tuning
can be documented, so
'an y
variables are involved that the
d ual practice depends on experimen-
ation, experience and a feeling for the
ib (coupled with a fair amount ofluck)
h at only the outlines of procedure can
ie given.
DRIVE CLUTCH
Speed tuning an engine usually sac-
carefully for wear or other damage . If
wear is abnormal, attempt to discover
the cause before completing the repairs
and returning the vehicle to service.
Excessive or
uneven wear on sides of
vee
belt may indicate pulley misalign-
ment, bent pulley half or improperly
adjusted idle speed . Examine pulley
faces for wear patterns or heat discolor-
ation. Determine and correct the cause
of trouble rather than just renew the
belt . Sheave parts should fit with a
minimum of clearance without
bin d ing . Apply a light coating of oil or
low temperature grease to sliding
parts, but make sure that no excess
lubricant will be thrown on belt or
sheave faces when unit is in operation.
Check for specific overhaul informa-
tion and disassembly notes in the unit
sections or illustration s.
rifices
torque at the low end to obtain a
power peak in the performance range.
The degree of "peakiness" depends on
the type of competition involved and
determines the tuning of the drive
clutch .
In a
family machine, the drive clutch
should engage smoothly at a r elatively
low engin e speed and u pshi ft smoothly
through the power range under all
combinations of throttle setting and
load . The converter package should
automatically shift down as necessary
to keep from lugging the engine.
With a "peaky" competition en gine,
engagement speed must be raised
above the stall-out point of engine
tuning and total balance of machine,
track surface and converter should
permit almost instantaneous accelera-
tion to peak horsepower range.
As previously stated, clutch engage-
ment speed can be raised by lightening
the c entrifugal weights or by strength-
ening the reaction spring. Clutch and
machine manufacturers; and some per -
Fig. 8-Cross sectional view
of governor centrifugal
weights showing: M-Face
movement and; Dotted
IInes-welght movement; to
high speed 'pos/llon. Kidney
type weight Is shown at
right while left-hand view
\\
shows curved cam-arm type
In
which pivot (P) moves
and fulcrum (F) Is fixed.
Removing material In
shaded area (E) will have
greater effect on engage -
ment speed; at shaded
area (X) will have greater
effect on shift pattern.
C. Gravit y cente rli ne
F.
Fulcrum p oint
M. Advan ce movem ent
P. Cen trif ugal pivot
Speed Tuning
formance specialists, make heavier
springs available . But sometimes the '
spring is not the whole answer. Centri-
fugal force increases geometrically as
speed increases and any inherent im-
balance is correspondingly multiplied.
Also, heavy centrifugal weights plus
high speed plus a correspondingly
strong balance spring in driven unit
exert heavy side pressure on drive belt,
resulting in increased belt wear and
frictional loss of power . For these rea-
sons, weight modification (or selection)
is also a widely
used modification tech -
nique .
A
new compensating spring for a
competition clutch should be com-
pressed in a vise overnight to pre-set
the spring before installation . Weights,
weight pins , rollers and similar parts
should be installed only in sets and
carefully weighed and balanced (using
druggists scales or equivalent) before
installation . :r weights are altered by
trimming, balance must be maintained
both as to total weight and configura-
tion . Dynamic balance and centrifugal
action are both affected by selection of
trim point . Refer to Fig . 8. As a general
rule, removing weight farthe st from
pivot point (P), from hea .v.y side of
gravity centerline (C), or nearest
pulley outer rim will have the greater
centrif ugal effect. And material nearer
pulle y rim will "weigh mor e", "'.'n a
dynamic balance ' st an dpoiut tha n
equal weight nearer the hub. Re-
moving we ight at shaded area (E) will
affect
engagement rpm to a greater
degree while removal from shaded area
(X) will have greater effect on shift
pattern . Do not remove material from
fulcrum point (F) of kidney weight
(right) or from roller contact area of
hammer weight (left) when lightening
the weights.
Paint , rust, gum or grease must be
removed from belt contact surfaces of
pulley faces and the surfaces kept
clean . Bushing surfaces, pivot pins,
rollers and other friction points must
c
315

i
Carbur etor malfun ctionin g can also
be caused by worn p
art s. Needle valve
and se at should be checked and
replaced as a unit if necessary. Needle
valves should be checked for grooves
caused by overtightening. Se
ats will
usually be damaged if this is the case.
Needle valve adjusting should be done
lightly to pr
event needle and seat
damage.
DISASSEMBLY. Ref
er to Fig. 4.
Remove r
et aining screw (15) and fuel
bowl (13). Knock out float pin and
remove float. Check float for d
ent s,
leaks and wear on float lip or in float
pin holes. Remove inlet needle (9) and
seat (8). Remove idle mi
xtur e needle
(21), main fuel needle (1) and springs.
Note condition of choke and
throttl e
sha
fts an d pl at es. If we ar e xis ts,
car bu reto r body ass embl y must be
renewed.
r1
~ · L . 3 ~
~
",'"
19 ~
l;,r r :;-?\ 5
11 _R ~8
18 16~ 1).-9 10
~:.;
C >-12
g-13
15~ -14
Fig. 4-Exploded view of typical Carter
Model UN" carburetor .
I. Main fuel needle
2. Spr-ing 13. Float bowl
3. Car
buretor body 14. Sealin/{ washer
4. Choke shaft 15. Retainer
5. Choke disc 16. Main jet
6. Choke detent 17.
Pl u~
7. Sea ling washer 18. Spring
8. Inlet valve
seat
19. Idle stop scre w
9. Inlet valve 20. Throttl e disc
10. Float pin 21. Idle fuel needle
II. Float
12. Gasket
~~ : ~h~ ~~fl e shaft
ASSEMBLY. In st all inlet seat and
needle.
Inst all float and float pin. Set
float level by inv erting carburetor with
float r
esting lightly on inlet needle.
Mea
sur e b etw een body gas ket flange
and float
at the point oppo sit e the
needle valve. The mea
suremen t should
be 11
/64 -inch . Fl o at adjus t me nt is
made by bending t ang conta cti
needle valve. Install new fuel b:
gask et, fuel bowl, r etaining scr
gask
et (if needed), and r et aining sen
Install main fuel needle. Install
mi
xtur e needle. Do not overtigh:
needles in seats. Make running adji,
m ents .
KEIHIN DIAPHRAGM CARBURETOR
KEIHIN diaphragm type ca
rbur etor s
are designed for snowmobile use and.
prior to 1972 produ ction, wer e available
in two series; 406 which is roughly
equivalent in size and application to
Tillotson HR; and 407, equivalent to
Tillolson RD.
Starti ng with the 1972 model yea r, a
new m
eth od of identification was used
Model number of all
carbur et ors begins
with
prefix l ett er s "CD," followed by a
number such as "33-28."
Fir st p art of
numb
er indicates throttle bore (in milli-
meters) and second p
art of number
indicates venturi diameter .
OPERATION
Fuel level (Main) di aphra gm (7- Fig.
5) is below fuel pump di
aphr agm (2). A
choke shu
tte r closes the carburetor air
horn to initiate the
sta rting mode.
Slow speed operation is controlled by
sett inz of idle adiustment needle (l)
and by a series of drilled discharge
p
ort s (See Fig. 6) lo cated below the
edge of closed throttl e shutt er. Drilled
p
ort s (th ree or four) are uncov er ed
Fig. 5- View of Keihin Diaphragm Carburetor
showing points of adjustment .
s equ entially as thr ottl e shut ter
moved from idle position, thus sUPI
ing additional fuel for c
orr ect mixt
as air flow increases. At high sp«
the primary v
entur i and main I
dis
char ge nozzle ar e brou gh t i:
operation. supplementing the fuel wh
continues to flow
thr ough the I
discharge p ort s. In this manner,
and air are balan ced throughout
op
eratin g range.
ADJUSTMENT
C arbur etors are divided into eo
and late typ es as outlined in
intr oo
Fig. 6- V iew of lower surface of cemu«
body showing idle bypass cover remove,
I. Gasket P. Puls e pa-
I. Idle bypass cover X. Fuel port
Fig. 7- View of lower surface of cetbu «
body wi th Idle bypass cover (/) and exp
sian plug 1M) installed . Refer elsa to Fig .
A. Adjusti ng st ud R. Return fitti ng
C. Check plug T. Sight tube
H. High speed needle 2. Fuel pump diaphragm
I. Idle needle 4. Lower gasket surface
L. Lo cknut
7. Op
erating diaphr agm
120

ntac ting
fuel bowl
g sc r e w
g
screw .
tall idle
ertighten
g
adjus t-
s
hutter is
us supply-
mi
xture
'gh speed ,
ma in fuel
ught into
fuel which
the idle
fuel
t he
'NGINES
Dry p ara gr aph s. Pr inciples of adjust-
lent a
re similar for all mod els but the
rec edure diff er s on early unit s which
la ve not been upd ated. The CD unit s
~ e shown in Fig. 5. On early unrnodi-
ne d units, check plug (C) was to the
~ g h t of re turn fi ttin g (R), or bleed plug
lreturn fitting was not in
st alled. Most
ea rly car bu ret o rs have been modified
oy insta lling l at e fuel pump body, in
Ihich case c
arbur eto r will be adj usted
~ a late unit.
FUEL
LEVEL. Fuel level must be
.
ecke d with engine ru nning. Install
. ught tube (
T-Fig . 5) as shown, then
ila rt and run engine at approx imate ly
1 50 0 rpm . Fu el level should rise . in
jlastic sigh t t ube t o low er g as ke t
illJ' face of upp er fuel pum p cover (4).
n models with early fuel pump body
sake sure sig ht tube is installed in
IGHT port opening and adj ust fuel
le vel to upper gask et surface of upp er
ro ver.
If fuel level is in
corr ect , loos en
Oc knut (L) and turn adj ust ing st ud (A)
iN to RAI SE fuel level or OUT to
LO WER fuel level.
NOTE: Some early models rna
,ock screw (19-Fig. 12) cure
idj usling stud (A- Fig. !;I I stead of
bc knut ( l).
\,,;. 1 , correctl y. adj usted at
J. raise re ar of machine and
... engine
at 3000 rpm; fuel level
~ o u l d not cha nge. If fuel level v ar ies
cor
rect adj ust ment ca nno t be ob-
fig . 8-Fuel pump d iaphragm (2) installed
oncarburetor body . Install large "0 " ring (3)
In d small "0 " ring on fuel ports (X) of fuel
pump upper cover (4).
tain ed, ov erhaul carbu reto r as outlined
in appro priate following paragra phs.
MIXT URE ADJ U STMENT . N orm al
intitial se
tt ings are 11/4-tu rns open for
idle mix
tur e adj ust ment scre w ( I- Fig .
5) and one-turn open for high
speed
mix tur e sc rew (H ). Final adjustments
must be m
ade for be st p erform ance
with engine
at o perati ng t emp er a tur e
and fuel level
prop erly adjusted. High
sp eed mix bur e mu st be rech eck ed
whenev
er idle mi xtur e has been read-
justed.
OVERHAUL
To dis asse mble th e Keihin di aphr agm
ca r bu
reto r, rem ove th e six Phill ips
head through-bo
lts and ca ref ully sepa r-
ate the units. Check thro
ttle shaft and
bores for w
ear and thro tt le shutte r for
d
amage and renew the carbure tor if
dam age is found . Choke components
a
re available and may he re newed,
howev
er, new scre ws must be used and
s
ta ked or inst all ed wit h "L octi te."
Rernovr l"g speed adj usting scre w
(11 I l ) and idle adjus tin g scre w (I),
,1 ,1 : examine tap er ed ends for dam age.
Renew scre ws if
tap er ed ends are
visibly ringe d or if ot
herw ise dam aged.
Renew car bure tor if adj usting scre w
seats are damaged.
Remove idle bypass cover (I
-Fi g. 6)
and its ga
sket and exa mine idle well
and por t
dr illings for dirt or gum. Soak
in so
lvent and blow out with com-
pressed air if dep osits a
re found. Do
not use a drill or wir e p
rob e in an
Fig. 9-Fue l pump upper cover (4) installed
on carburetor body . Position check valve (5)
over
upper cover w ith the three cente ; flaps
centered over inlet ports (lP) and fuel
passages (X) open . ' .
Carburetor Service
a tte m pt to clea n port s. Reinstall idle
b
ypa ss c ove r (I) as shown in Fig . 7,
tighte ning retain ing scre ws sec ure ly.
Check main nozzle
expa nsion plug (M)
to be sure it is
tight and c orrec tly
inst alled. Do not atte m pt to re move
expa nsion plug or main nozzle.
When reass
emb ling carb uretor, fuel
main and idle supply passage (X ) must
remain open. In
st all gasket (1) and
pump diaph ragm (2- Fig. 8) makin g-
su re holes for fu el passage s a lig n.
In
st all the l ar ge " 0" ring (3) and the
two small "
0" ring s (in fuel po rts "X")
in fuel pump upp er cover (4) and
po
siti on cove r ov er t he dow el s in
throttl e body .
Inst all check valv e (5- Fig. 9) making
sure the th ree middle flaps are cen-
t
er ed over inlet p ort s (IP) in upp er
cover ( -1 ) and t hat fuel p ort s (Xl align.
The six check flaps MUST be in good
condition.
If inlet needle valve seat is to be
r
enew ed, remove Phillips head scre w
(
S-Fi g. 10) and r et ain er (R). In v ert
pump body and remove valve lev er,
spring and needle valve; then using a
Fig . 10-Top view of fuel pump tower
body (6) show ing outlet port» (OP) and top
side
of inlet valve seat (V). Seat is secur ed
by
tetsinet (R) and screw (S). Fuel passage
potts. ale at (X).
Fig .
ll-Inlet valve lever button (B) should
be flush with ttoor on bottom side of valve
body (6). Inlet valve seat is at (V) and inlet
needle at (N).
121

CarburetorService
ENGINE~
Fig . 14-Exploded view of
operat ing diaphragm (7),
spr ing (8),
spr ing seat (9)
and regulator cover (10).
Upper end of adjusting
stud is shown at (A).
5---, .......
;--11
16
17
Fig. 12-Exploded v iew of KEIHIN d iaphragm
type carburetor showing component parts.
S ight tube (21) is used to set fuel level and
. is not a part of the carburetor .
I. Throttle body
2. Low speed screw 12. Bleed plug
3. High speed needle 13. Spring
4. Low speed needle 14. Pivot shalt
5. Pump diap hragm 15. Valve lever
6. Pump upper cover 16. Regulating diaphrag m
7. Gasket 17. Spring
B. Pump check valves lB. Regulator cover
9. Pump (regulating) body 19. Lock screw
10. Inlet fitti ng 20. Adjust ing screw
11. Inlet needle & seat 21. Sight tube
Fig.13-0perating diaphragm (7) and associ-
ated parts installed on lower side of valve
body.
7. Operating diaphr agm
B. Spring P. Pulse fitti ng
9. Spring seat R. R
eturn fitting
F. Inlet fuel fitting X. Fuel passages
good pin punch of appropriate size,
drive valve seat (V ) 1I ,V •• >I out of
valve body. Valve h,ts are available
in standard size and OD oversizes of
0.01 , .d 0.002 mm. Oversize valves
a "il t'iied by one or two annular
<J"' S around outside of body while
standard body is smoot h. Rein stall
retainer (R -Fig. 10), needle valve and
lever, then check height of actuating
button (B-Fi g. 11) which should be
flush with valve body floor. Adjust if
neces sary by b ending t ang whicl
contacts valve needle (N).
Fig. 13 shows operating diaphragn
(7), spring (8) and spring seat (9
correctly positioned. Part s are showr
exploded in proper order in Fig. 14. Ar
initial starting point for adjusting stue
(A) in regulator cover (1 0) is with tW I
threads showing when viewed fron
inside as shown. Adjust the assem bled
carburetor after installation as previ
ously outlined.
KEIHIN
TYPE FLOAT CARBURETOR
WITH BUTTERFLY THROTTLE
Carburetors are identified by a model
number which consists of a let ter prefix
"BD" followed by a set of numb ers such
as "44-38". First par t of number in-
dicates thr ottle bore (in millimeters) and
second p art of number indicates venturi
diameter.
ADJUSTMENT
FLOAT LEVEL. Float is adjusted by
bending metal tang between float body
(16- Fig. 14A) and float pin (17). As
shown in Fig. 14B, distance (D) should
be 0.48-0.67 inch when carburetor is
tilted ~t a 20-30 degree angle.
IDLE SPEED. Idle speed is adjusted
by turning screw (8-Fig . 14A). Idle
speeds vary from model to model, con-
sult respective manufacturer specifica-
tion for recommended speed setting.
IDLE MIXTURE. Idle mix tur e ae
justment is done by turning sere.
(6- Fig. 14A). Start engine and bring u
to normal operating temperature. Tur
screw either in (lean) or out (rich) to ot
tain an even engine idle. Readjust idl
speed to recommended setting after idl
mixture is set .
MAIN JET. To insure top p erf orn
ance of engine, main jet (13-Fig . 14 ..1
may need to be changed if there is :
2000 feet change in altitude or an 1:
degree F change in temperature. Whe:
altitude or weather temperature if
creases a lower number of jet should b
used. Whenever altitude or weathe
temperature decreases a larger numbe
of jet should be used. Caution should b.
taken especially when operating at .
lower altitude, too lean of fuel mixtur.
could shorten engine life.
.
• .. ~ ~'I~ ' " ......' h. : ,l ...... ,,{. "'~. • .. tj;..~.. .." \ ~ .
122

RolI·Q·Flex, Rupp VEHICL
EngIne
---carburator---
Clutch
Model
Make
Model
Diapl.
Make
Model
Sproc:ket
Ratio
Chain
Size Make SNit
Cent.
Bo
Nun
RAIDER CONT. 1975
Eagle . . . ... . . Ko hler
Do
uble Eagle . Kohler K340-2AS
K440-2AS 339cc 436cc
Walb ro
W
albro
WDA-38
WRA-34(2) 13
:29
15:31 40
428 Sal
sbury 780
sa
lsbury 850 12.6
12.6 6008
6038
NOTE: Production Discontinued.
ROLL-O-FLEX
1971
Apache 312 .. .
Apache 340 . ..
CCW
CCW CCW312 ' CCW340/ 1 312cc
339cc Kelhln Kelhln CU34-406
CD34-406 14:36
14:36 35-2
35-2 Eastern
Eastern 10V,
10' 12
SV1::
SV13
Apache 400 .
..
CCW CCW4oo /1 398cc Keihln CD34-406 15:36 35-2 Eastern 10
'12
SV13
Apache 440 .
..
Comanche 295 CCW
CCW CCW440 /1
CCW290/1 436cc
290.1cc Kelhin Kelhln CD34-406
CD34-406 16:36
14:36 35-2
35-2 Eastern
Eastern lOV,
10 '12
SV13
SV13
Comanche 340
Comanche 400
Comanch e 440
Cherokee 340 .
Cherokee 400 .
CCW
CCW
CCW
CCW
CCW
CCW340 /1
CCW4oo/1
CCW440 /1
CCW340/1
CCW4oo/1
339cc
398cc
436cc
339cc
398cc
Kelh in
Kelnln
Kelhin
Ke
lhln
Kelhln
CD34-406
CD34-406
CD34-406
CD34-406
CD34-406
15:36
16
:36
17:36
14:36
15:36
35-2
35-2
35-2
35-2
35-2
Eastern
Eastern
Eastern
Eastern
Eastern
10V,
10V,
10V,
10V,
10'
12
SV13
SV13
SV13
SV13
SV13
Cherokee 440 . CCW CCW440/1 436cc Ke
ihln
CD34-406 16:36 35-2 Eastern 10
'12
SV13
1972
Comanche
292Y
.. , .... Yamaha SL292 292cc Kelhin CD34-406 14:38 35-2 Yamaha 10¥--11 7148·
Comanche ChI Yamah a SL292 292cc Kelhln CD34-406 14:36 35-2 Yamaha
10' 4- 11 7148-
Apache 292Y
..
Yamaha SL292 292cc Kelhln CD34-406 14:36 35-2 Yamaha 1
0' 4-11 7148-
Apache 338Y . . Y
amaha
338 338cc Kelhm CD42-38 15:36 35-2 Yamaha 10'4 -11 7148-
Apache 396Y . . Yamaha 396 396cc Keihln CD42·38 16:36 35-2 Yamaha 10'1,-11 7148·
Apache 433Y
..
Yamaha 433 43: Keltiin CD42-38 16:36 35-2 Yamaha
10' ,, -11 7148·
Cherokee 396Y Yamaha 396
Kelhln
CD42-38 16:36 35-2 Yamaha
10' 4 -11 7148·
Cherokee 433Y
GT292SS
... ..
GT338SS .. . . .
Yamaha
Yamaha
Y
amaha
433
29;J
J it!
J_~
2cc
338cc
Kelh ln
Kelhln
Kelhln
CD42-38
CD42-38
CD34-406(2)
16:36
14:36
16:36
35-2
35-2
35-2
Yamaha
Yamaha
Yamaha
10' /,-11
10'/,-11
10'4 -11
7148-
7148
7148-
GT433SS . . .
..
Yamaha .J3 443cc Keihln CD34-406(2) 17:36 35-2 Yamaha 10'4 -11 7148-
1973
c' Ya
matia
292
29 2c ~ Ke:hlii
\.Iu .J .. •.. VO 14:36 3502 Yamaha 10'4 -11 7148·
j ~ Y .. Yamaha 338 338cc Keihln CD42-38 15:36 35-2 Yamaha 10'4 -11 7148·
,"'"' he 396Y
..
Yamaha
Apache 433Y : . Yamaha
Cherokee 396Y Yamaha
Cherokee 433Y Yamaha
GT292SS
.. . . . Yamah a
GT338SS . .
.. .- Yamaha
GT433SS . . .
..
Yamaha
396
433
396
396
292
338
433
396cc
433cc
396cc
396cc
292cc
338cc
433cc
Keih ln
Kelhln
Kelhln
Kelhln
Keihln
Keihln
Keihln
CD42·38
CD42-38
CD42-38
CD42-38
CD42-38
CD42-38
CD42-38
16:36
16:36
15:36
16:36
14:38
16
:36
17:36
35-2
35-2
35-2
35-2
35-2
35-2
35-2
Yamaha
Yamaha
Yamaha
Yamaha
Yamaha
Yamaha
Yamaha
10' /,-11
10'/,-11
10'1, -11
10'1,-11
10'1, ·11
10'4·11
10'/, -11
7148·
7148·
7148-
7148-
7148-
714!l
7148·.
1974
Apache . .. . . . .
Apach e .
.. . .. .
Apache. . . .
...
G.T. . . . . .....
G.T. . . . . . . . . .
G.T. . . . .
.. . . .
Comanche .
.. .
Wild One . . . . .
Yamaha
Yamaha
Yamaha
Yamaha
Yamaha
Yamaha
Yamaha
Kohl er
338Y
396Y
433Y
292S
338S
433S
292S
K340-2AS
339cc
396cc
433cc
292cc
338cc
433cc
292cc
338cc
Ke
ihln
Keihin
Kelhin
Kelhln
Kelh ln
Keihln
Kelhln
Dual Mlkun i
407
407
407
407
407
407
407
15:36
16:36
16:36
14:36
16:36
17:36
14:36
16:36
35-2
35-2
35-2
35-2
35-2
35-2
35-2
35-2
Yamaha
Yamaha
Yamaha
Yamaha
Y
amaha
Yamaha
Yamaha
Comet
11-11'/,
11-11'I,
11-11'I,
11-11'I,
11-11'I,
11-1I 'I,
11-11'I,
11-11'1,
1204·03C
1204·030
1204-030
1204·03C
1204·030
1204·030
1204·03G
NOTE :
Production Discontinued.
RUPP
1966
ss II . .. . . . . ..
SS III . .
.. . . . . JLO
H
irth
L252
53R 247cc
300cc Till
otso n
Tillot son HL187A
HL214A 10:30
11:30 35-2
35-2 SalSbury
Salsbury I I V,
11 v, 11831
l 1H'1I
SS25O
.. ... • ..
SS3OO. . . .. . ..
JLO
H irth
L252
53R 247cc
300cc T
illotso n
T
illoison
1967
HL167A
HR3A 1
1;26
11:26 40
40 Own
Own
'1 '/,·
'I If .' 1;'("11
I ;'IJ~ I
S port 281. . _ ..
1968
Sachs SA280
ZTl cc
G1"3OO . __
T./lOl f>V fl
H L ~ 7&
. . _. _ Sachs SA290
,:t~
'1', 1'
297cc TlI'CIlJVfl 1' 111, /,,1
H~1t
, ~ :til Ii l'd
'JI,I' I
I/ I I, / v/ ur.
S2B1 . . . . . . . . . SiGns
1Wh
~
m ~
GT300 .. • . . . _. 5.iochs
T,I ICA 3oVfl
SA2!l() H k l~ 1t
297cc n.
:as
G137V. . . . . . " 5.iochs
T,lIo
tsvn ~ z
SA370 HF!
j(jA
( JII II
l Z:28
368cc
T iliOlson
HD14A J!r2 Own
..
"y If'"
,. 111',4
13;28 J!r2 111',4
Own
26
., y"
111\4 t ,