Yamaha SL338D - Page 92

ENGINE MAINTENANCE - Carburetion and Fuel System
Trouble Shooting
Trouble
1. Overflow
2. Hard starting
3. Rough idling
Cause
o Inlet valve is dirty.
o Inl et co ntrol valve does not close perfectly.
o Inlet contro l
smoothly.
valve does not operate
Standard surf ace
Adjust tl1e edge of th e
lever
to 0.00 12" (0 .3 n1m}
high er position from th e
standard s urf ace.
too high A
I
push up (bend)
proper a
0.0012" (0 .3 mm) ± 0.1
Standard surface
too low
c
Fig. 7-34
push down
o Main diaphragm is not correctly installed.
o Regulator internal pressure is too high.
o Fuel passage is clogged.
o Fuel pump is inoperative.
o Choke does not open perfectly.
o Fuel supply is insufficient.
o Fuel supply is in excess.
o Adjustment is incorrect.
o Inlet control lever end is incorrect in
height.
o Fuel pump operation is not smooth.
o Both carburetors do not synchronize.
-86-
Re111edy
Remove inlet valve and clean it.
Replace i 11 let co ntr ol va l ve. (W h en replacing
it, make sure the seat SL1 rf ace is free of
scratcl1es.)
1. Repl ace irilet cont ro l lever.
2. Reinstall
inlet con trol lever cor r ec tly.
(A djust the end of lever to the position as
sl 1ovvn in Fig. 7-34.)
Rei nstal I main diaphragm correctly .
Reduce
the pressure.
Clean fuel
passage with gasoline, and bl ow it
. out carefully with air.
Check
impul se port, fuel pump diaphragm,
and check valves (inner and
outer).
Reassemble it correctly. Check the linkage
between
both ca rburetors.
Use
primer pump. Refer to Sta rting Proce-
dures
on the fo ll owi ng page.
Refer
to C of Starting Procedure.
Readjust
as specified. Particularly, check
regulator fuel lever and readjust
as required.
Readjust. (Refer
to ''Overflow''.)
Refer to ''Hard Starting''.
Check synchronization.