DS 19 OPERATION No. DS 112-0 : Adjusting the valve rocker clearances. Op. DS 112-0 68
PARTICULAR POINTS
Valve clearance = 0.008 in (0.20 mm) for the inlet and 0.010 in (0.25 mm) for the exhaust.
Adjust the valves of one cylinder with the piston at top dead centre, end of compression, the valves of the corresponding cylinder are then at
the point of balance: 1st cylinder, the valves of the 4
th
cylinder being at the point of balance, 3
rd
cylinder, the valves of the 2nd cylinder
being at the point of balance, 4
th
cylinder, the valves of the 1
st
cylinder being at the point of balance, 2
nd
cylinder, the valves of the 3
rd
cylinder being at the point of balance.
TOOLS
ADJUSTING
1 Remove the air filter and pipe assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 – 17 mm box spanners
2 To remove the cylinder head cover (see Pl.1):
a) Disconnect the leads from the sparking plugs. Remove the rubber and bakelite caps from the sparking
plug tubes.
b) Remove the sparking plugs (spanner 1603-T, see Pl. 16, fig. 7) so as to avoid breaking the electrodes
when moving the cylinder head cover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Spanner 1603-T
c) Remove the cylinder head cover, do not mislay the sealing joints (4) of the sparking plug tubes . . . . . . 12 mm box spanner
3 Adjust the clearance of the valve rockers to :
0.008 ins (0.20 mm) for the inlet valves.
0.010 ins (0.25 mm) for the exhaust valves.
Adjust the valves of one cylinder with the piston at top dead centre, end of compression. The valves of the
corresponding cylinders are then in balance, that is the inlet valve is at the start of admission and the
exhaust valve at the end of exhaust. (Turn the engine by means of the starting handle, after having
pressed the auxiliary clutch control forward and upwards).
Adjust the valves of:
1
st
cylinder, the valves of the 4
th
cylinder being at the point of balance.
3
rd
cylinder, the valves of the 2nd cylinder being at the point of balance.
4
th
cylinder, the valves of the 1
st
cylinder being at the point of balance.
2
nd
cylinder, the valves of the 3
rd
cylinder being at the point of balance.
4 To fit the cylinder head cover.
With Hermetic, stick the gasket to the cover only. Clean the gasket and its seating on the cylinder head.
Clean the joint face, engine side. Make sure that the sealing joints (4) are properly located in the
sparking plug tube caps (3). Tighten the nuts fixing the cylinder head cover (leather and plain washers). 12 mm box spanner
5 Fit the air filter and pipe assembly. Tighten the fixing nuts (spring washers). Tighten the hose clip on
the pipe to the carburettor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 – 17 mm box spanners
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