Valve Seat Inspection/Refacing - Honda NSA700A DN-1 2009 Service Manual

CYLINDER HEAD/VALVE

VALVE SEAT INSPECTION/REFACING

INSPECTION
Clean all intake and e x h a u s t v a lv e s th o ro u g h ly to
re m o v e carbon deposits.
A p p ly a th in coat o f Prussian B lue to each v a lv e
face.
T a p th e valve ag a in s t th e v a lv e seat several tim e s
using a h a n d -la p p in g to o l, w ith o u t ro tatin g v a lv e , to
m ak e a clear pattern.
R e m o v e the v a lv e and inspect th e v a lv e seat face.
NOTE:
• T h e v alve c a n n o t be g ro u n d . If th e v alve fac e is
burned o r b adly w o rn or if it contacts th e seat
u n even ly, replace th e valv e .
Inspect the v a lv e seat face for:
• U neven se at w id th :
- Replace th e v a lv e and reface th e valve seat.
• D am ag ed face:
- Replace th e va lv e an d reface th e valve seat.
• Contact area (too high o r to o lo w area):
- Reface th e v a lv e seat.
Inspect th e w id th o f th e v a lv e seat.
T h e valve s e a t c o n tact sh ould be w ith in th e sp eci­
fied w id th and even all aro u n d th e circum feren ce.
STANDARD:
SERVICE LIMIT: 1.5 mm (0.06 in)
If th e valve seat w id th is n o t w ith in specification,
rcfacc th e v a lv e scat.
9-20
0.90 - 1.10 mm (0.035 - 0.043 in)
H A N D -L A P P IN G TOO L
T O O L O W
W ID T H
T O O H IG H