Suzuki Engine 2002 GRAND VITARA SQ420 Service Manual page 446

• Valve seat repair :
A valve seat not producing a uniform contact with its valve or
showing width of seating contact that is out of specified
range must be repaired by regrinding or by cutting and
regrinding and finished by lapping.
a) VALVE SEAT : Use valve seat cutters (1) to make two cuts
as illustrated in figure. Two cutters must be used : the first
for making 15° angle, and the second for making 45° angle.
The second cut must be made to produce desired seat
width.
Seat width for exhaust valve seat
1.1 – 1.3 mm (0.0433 – 0.0511 in.)
b) INTAKE VALVE SEAT : Use valve seat cutters to make
three cuts as illustrated in figure. Three cutters must be
used : the 1st for making 15° angle, the 2nd for making 60°
angle, and 3rd for making 45° angle. The 3rd cut (45°) must
be made to produce desired seat width.
Seat width for intake valve seat
1.1 – 1.3 mm (0.0433 – 0.0511 in.)
c) VALVE LAPPING : Lap valve on seat in two steps, first with
coarse size lapping compound applied to face and the sec-
ond with fine-size compound, each time using valve lapper
according to usual lapping method.
[A] : Intake valve seat
[B] : Exhaust valve seat
Cylinder Head
• Remove all carbon from combustion chambers.
NOTE:
Do not use any sharp-edged tool to scrape off carbon. Be
careful not to scuff or nick metal surfaces when decar-
boning. The same applies to valves and valve seats, too.
ENGINE MECHANICAL (H25 ENGINE) 6A2-71