Adjusting The Slow Speed; Adjusting The Idle - Honda C50 Shop Manual

3.7 CARBURETOR 43
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::ssi e black exhaust smoke is evid ent
--e- ediate speed, it is an indi ca tion
: : -i::-
a fu el mixture and therefo re, th e
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e hould be lo wered one step.
=-
- ·-g
ac~elera tio n
o r at int ermediat e speed,
-e e"gine sputters, misses or does not respo nd,
--e ' e ne edle sho uld be raised o ne st ep.
---:::-le valve cut-aw ay . (Fig. 3- 1 04)
- e larger the number stamped on the cut-away,
eaner w i ll be th e f uel mix ture. Whe n making
he adjustment o f th e th rottl e va lve, the slow
speed should also be co nsid ered together w ith
th e i ntermediate speed si nce the effecti ve rang e
of the thro ttle is very broad.
c. Adj usting the Slow Speed
The fuel mi xt ure ad justm ent betw een i dli Ag and
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hrottle o pening is made by the air screw and the
hrottle valve cut -away.
(l
l Ai r screw
The fuel mix ture adjust ment for idling is made by
th e air screw.
Turn to the right fo r a richer mixtur e. Tur n to
th e left f o r a leaner mixtur e. The air scr ew no t
o nly affect s t he idling but also the slow sp eed,
therefo re, th e fue l mix ture shou ld be adjusted
w it h the throttl e slightly o pe ned to o btain a
smooth o peratio n.
!21 Thro tt le valve c ut-away
Th er e may be a case where t he ad justm ent can-
not be o btained by th e air scr ew o nly, in the
vici nity o f
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throttle opening. In this case, if
t he fue l mix tur e is too rich, replace t he cut-away
with one o f a larger numb er and if t oo lean,
replace with o ne o f a small er number.
d . Ad justing th e Idle (Fig. 3- 105, 3- 106)
The idli ng ad justment is perf o rm ed by the throttl e
stop scr ew a nd th e air scr ew in the fo llo wi ng manner.
( ll
A d just th e idli ng sp eed to the sta ndard 1200
RPM by th e use o f th e thro ttle sto p scr ew .
!21 N ext, t urn t he air screw slowly back and fo rth
to th e hi ghest RPM.
(31 Upon locating t he poi nt o f hi g hest RPM i n (2)
above, reset th e engine speed t o th e standard
RPM .
(4)
Rework th e air screw to assur e that it is set at
t he pro pe r setting.
(5)
If any change exist, repeat
(3 )
!41 above. The
check sho uld be made between
78
to 1}6 tur n
o f th e ai r scr ew.
Cu t -Away
S ep position
I
Jet need le
Figure.
3- 104.
Jet needle and cu t-away o f th e throttle
valve
Thrott le st op
'
Fig ure
3- 105.
Idl e ad justment
Fi gure 3- 106. Idle adjustment !S50, S65)