Ignition Timing Adjustment; Valve Clearance - Honda C50 Shop Manual

86
Figure 6- 3. ;.
Thick ess gau ge :
Figure 6- 4. Adjusting tappet cleara nce
Figure 6- 5. Locking the adjusting nut
Figure 6- 6. Aligning to the " F " mark
6. MAINTENANCE
INSPECTION
Th e tappet clearance wil l have a great deal of effect
on the va lve timing. If the clearance is too small, it
may prevent th e valve from fully closing and r esult in
pressure leak at the va lve. On the other hand, an
excessive t appet c lear ance will produce tappet no ise
and resu lt in . noisy engin e operation. The ta p pet
clearance w il l ·have a varying degree of effect on th e
e gin e power o utput, engine operation at slo w sp eed
~d
e gin e noise.
V alve clearance
emove the left crankcase cover and a lign the
· i i g mark " T" on the flywheel with the align-
-:er' mark on the crankcase. (Fig .
6- 3)
e-,o e 'he appet adjustin g cop on the cylinder
~eaa_:a 'ld
check th e clear ance between the
od;us'i g screw and the va lve. (F ig.
6-4)
If
he o lve is ac ua t ed bv the rocker arm and
is in the open position, rotate the flywhee l on e
complete turn to set the piston at top dead
center of the compression stroke, and t hen
perform the check.
2. Adjustment
Loosen t he adjusting scr ew locking nut end make the
adjustment with th e adjusting screw t o obtain the
stan dard c learance of 0.05 mm 10.002 in) for both
the inl et and exhaust valves.
Turn screw c lockwise for closer clearance.
Turn scr ew counter clockwise for wider clearance.
The tappet c learance ad ju siment for the C50, C50M,
C65, C65M, S50, S6 5 are identica l.
(Note)
1 I I The adjustment must be made with a cold engine
a nd t he c learance measured wit h a t hickness
gauge.
121 When locking the adjus\ing scr ew, hold t he screw
to prevent its turning. (Fig.
6- 5)
3 . Inspection
a. Check to make sure that t he tappet c lear ance
is w ithin sta ndard t o lerance. Too sma ll o clear-
ance wi ll cause t he va lve t o stay open with
a consequent pr e ssure leakage and r esulting
in hard st arling or no starting a t a ll.
b. Check for improper valve t iming.
c . Check for stret ch in the cam chain.
d. Check for any slippage o f the timing sprocket .
3. IGNITION TIMING ADJUSTMENT
An impr oper igni' ion t iming. regardless of the accuracy
of the va lve timing o r the p r oper compression p r e-
ssure, w ill no t realize a satisfact o ry engin e performan ce.
Ignit ion timing out of adjustm ent w il l seriously affect
engine power o utput as we ll as t he fuel consumption.