Specifications

eiYamaha Motor Corporation, U.S.A., 1979 All rights resered. Any reprinting or unauthorized
use without the written permission of Yamaha Motor Corporation, U.S.A., is expressly prohibited.
1. Romr pointer
2. Timing plate
7. Check the ignition timing (refer to page
3).
8. If the ignition timing is incorrect, loosen
the special bolts and move the pick-up
plate until the “F” and pointer marks
align.
9. After the ignition timing is properly
adjusted, tighten the lower special bolt
until the head shears off.
1. “TORX” socket
10. Back off the upper special bolt 3 or 4
turns and apply a liberal amount of an
epoxy adhesive around the bolt thread.
Retighten the bolt until the head shears
off.
NOTE:
A special socket (90890-01308-00) is neces-
sary for tightening these special bolts. The
heads will shear off when the bolts have been
properly torqued.
D. CARBURETOR
1. Specifications
Main jet
Jet needle
Needle jet
Starter jet
Float level
Pilot jet
Pilot screw
Fuel valve seat
Engine idle speed
# 132.5
5HX12
Y-O
# 30
27.3
+ 0.5 mm
(1.075 ?r 0.020 in)
# 42.5
Preset
2.0 mm (0.079 in)
1,200 r/min
1
2. Inspection And Correction
a. Examine the carburetor body and fuel
passages. If contaminated, remove all
component pieces, wash the carburetor
in a petroleum-based solvent. Blow out
all passages and jets with compressed air.
-CAUTION:
.
Do not use caustic carburetor cleaning
solutions.
b.
C.
d.
Examine the condition of the floats. If
the floats are damaged, they should be
replaced.
Inspect the inlet needle valve and seat
for wear or contamination.
Replace
these components as a set if required.
Inspect the vacuum piston and rubber
diaphragm. If the piston is scratched or
the diaphragm is torn, the assembly must
be replaced.
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