Matchless 1964 G12 650, Инструкция

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TO REMOVE T H E VALVES
First remove rockers from cylinder head (see illustration 12)
The importance of correctly locating the valve spring seats is stressed, the wide face
of the seat abuts against the cylinder head. Reversal will make the springs coil bound
and cause damage to the valve gear. Proceed by removing the rockers (see illustration
12 for assembly sequence). If a valve spring compressor is not available, use a wood
block 2" in cube to support the valves with the head on a bench.
Compress the springs to extract the split collets, which are a taper fit. A sharp tap on
the spring collar will release them.
REMOVE CARBON DEPOSIT
See details for single cylinder engines, page 32.
TO REMOVE VALVE GUIDES
Both guides are a force fit and located by circlips, the cylinder head must be uniformly
heated, the guide can then be pressed out of the port sufficiently to remove the circlip.
Reheat the head, press down the guide from outside the port.
VALVE G R I N D I N G
If the face of the valve is deeply pitted, the seat should be refaced with equipment designed
for this purpose. The seat angle is 45 degrees. Prolonged grinding will make the valve
face and seat in the head saucer-shaped and impair the gas seal.
Use fine grinding paste, moving the valve backwards and forwards, not continuously
in one direction, until an unbroken matt surface is obtained. Raise the valve from time
to time during this process, the grinding paste will " b i t e " better.
Usually the inlet valve needs little attention.
A piece of rubber tube with a bore diameter of ¼", part number 011381, can be used
for manipulating the valves for grinding.
All traces of abrasive must be removed after grinding, particularly from the valve guides.
Apply a little oil on the valve stems before refitting.
R E M O V I N G CYLINDER BARRELS A N D PISTONS
Unless it is desired to inspect the pistons and rings,
during decarbonisation, they are, as already advised,
best left undisturbed.
Having removed the cylinder heads withdraw the cylinder barrels by:
Lift away the four push rods, identify them for re-fitting and lay aside.
Dealing with one barrel at a time, exert upward pressure on a barrel, slightly rocking
to and fro while doing so, and steady the piston with one hand as it emerges from the
barrel.
Cover the crankcase throat with clean rag to prevent the entry of foreign matter.
To remove a piston
Using 011188 circlip pliers, contact one of the gudgeon pin circlips and, with a rotary
motion, gently withdraw the circlip from its housing. The gudgeon pin may then be
pushed out of the piston which action frees the piston from the connecting rod. (Being
a parallel, floating fit in the piston and connecting rod small end it is immaterial from
which side the gudgeon pin is withdrawn.)
NOTE—It may be necessary to apply a little heat to the piston to permit free gudgeon
pin removal and replacement.
Rings may be removed from a piston by peeling off or by introducing behind them
three thin and narrow metal strips, equally spaced round the piston, and then sliding
them off, taking care not to scratch the piston.
Carefully examine the contact edge of each piston ring and replace any which do not
show a bright surface over the whole circumference.
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