APRILIA V990 Manual page 48

DISASSEMBLING THE ENGINE
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Follow
N
Unscrew and remove the closing screw (16) complete
with seal (17) and remove the complete chain tightener
(18).
N
Insert an appropriate drift (Ø 7.5 mm) (19) in the upper
countershaft hole (20).
a
CAUTION
When loosening the nut M14x1 (21), counter the force
with the drift (19) so as not to strain the driving chain.
N
Unscrew and remove the M14x1 nut (21).
N
Remove the counterweight (22) from the upper coun-
tershaft (23).
a
CAUTION
Be careful to keep the key (24) from dropping into the
chain compartment. Cover the chain compartment
with a clean cloth.
N
Withdraw the driven gear (25) and remove it.
N
Remove the key (24).
N
Pull the chain guide shoe (26) out from above.
NOTE
In order to be able to reassemble the two gear
wheels (12) (13) correctly, proceed as follows: before re-
moving them, use a felt tip pen to mark the left and right
gear wheels with LH and RH, respectively, and the gear
wheels and the camshafts with a reference mark (A).
N
Release the two gear wheels (12) (13) from the timing
chain (27), then withdraw and remove them.
a
WARNING
Before removal, the three T.C.E.I. M6x14 screws (28)
must be marked so that they are refitted in the right
place; danger of major engine damage and physical
injury.
N
Unscrew and remove the three M6x14 T.C.E.I. screws
(28).
N
Withdraw the driving gear (9) and remove it.
N
Unscrew and remove the three M6x10 T.C.E.I. screws
(29).
N
Unscrew and remove the two M6 T.C.E.I. screws (30)
with the relevant washers and remove the chain guide
(31).
N
Let the timing chain (27) drop into the cylinders chain
compartment.
N
Unscrew and remove the two M6 T.C.E.I. screws (32).
N
Rotate the upper balance shaft (23) upwards and with-
draw it.
31 30
30
28
3 - 12
- 00
Follow
24
29
25
23
9
27
9
20
21
22
28
9
ã
29
13
32
27
V990 engine
18 17
13
12
26
19
22
25
30
31
12
26
Release 00/2001-06
16
21
24
23
A