Rotax 912-UL - 9.5 Propeller gearbox

6.6.4)-'Valve seats
Pay
attention
to
clean
sealing
face
of
valve seats.
If need be, regrind, using
emery
paste.
At the
presence
of burning
spots ordeformation,
remachine seats
by
utilizing
valve
seat
machining
jig.
Machine
first
seat to angle of
45o.
Correction
of
sealing
width
to the specified
value O
by
subsequent
machining under an angle of
l50
and
35o
resp.
30o.
Valve seats are shrink
fitted into
the
head, therefore
renewal
of the
seats
is not
planned.
Reworking of the
seats
must not
exceed 0,2
mm
(0,008
in.).
Sealing
face width
O
intake
valve 1,4
+
1,9 mm
(0,055 +
0,075
in.)
exhaust valve 1,5
+
2,0 mm
(0,059 +
0,079
in.)
d=9
Sealing
seat
inside dia. @
intake valve
34,7
+35,05
mm
(1,366+
1,380
in.)
exhaust
valve 29,0
+29,35
mm
(L,742+
1,156
in.)
Clearance angle @
intake
valve
seat:
35o
exhaust
valve
seat: 30o
6.6.5)
Valves
Check valve
head for
wear and
warpage
(max.
allow-
able out of true
is
0,03
mm
(.001
in.) at outside
@
of
valve head). Sealing
face
of
valve head
is
armoured.
Therefore
don't
rework valve
head
but sealing
gnnd-
ing
by emery
paste
is
practicable
(see
chapter 6.6.2).lt
necessary, renew valve.
Minimum rim thickness
1,2
mm
(0,047
in.).
6.6.6) Valve
springs
2
springspervalve arc fitted. Same
springson
inletand
exhaust valve. Visual check
for
fracture
and deforma-
tion.
Dimensions of
frec
length,
inner
spring
free length,
ourcrspring
spring
rate, inncr spring
spring rate, outer spring
wirc
sizc, inncr spring
wire
size, outcr spring
new
35,0
mm
37,0
mm
13,25 N/mm2
33,25
N/mm2
2,3
mm
0
3,5
mm4
(1,378
in.)
(13s7
LL)
(O522N/in.')
(1,309N1n.2)
(0,091
in.0)
(0,138
in.
O)
wear
limit mm
(in.)
y,0
(1,339)
36,0
(1,417)
Actual spring
length ought to be as equal
as
possible
on inlet- and
outlet
side.
If need be, exchange.
I NOTE: