D14/4
ENGINE
B7
FIG. B6.
Using service tool No.
61-3791.
BIG-END BEARING
While the cylinder is off, opportunity should be taken
to test the big-end bearing for wear. This can be
achieved by taking hold of the connecting rod and
pulling it upwards until the crank is at top dead centre.
Whilst holding it in this position, try gently but firmly
to push and pull the connecting rod in the direction of
its travel, in order to detect any play. If the big-end is
in good condition there should be no free movement in
this direction, although it may be possible to move the
rod sideways,
i.e.,
at right angles to the axis of the
machine. Should vertical play in the big-end be
detected and you do not feel qualified to assess
whether the amount in evidence is permissible or not,
then you should seek expert advice. This point is not
likely to give much trouble however, providing that
the engine has been carefully used and adequately
lubricated, for the big-end bearing is of ample
dimensions for the work it has to do. If the big-end has
deteriorated as the result of neglect or abuse, it should
be replaced as detailed on page B12, though unless
you have the necessary experience and facilities for
this type of work it is preferable to hand the job over
to an expert repairer.
REASSEMBLY AFTER DECARBONISING
If the piston was removed from the connecting rod,
replace it in its original position, (
i.e.,
with the piston
ring gaps at the front). Before fitting the gudgeon pin,
smear it with oil and do not forget to replace the
circlips. Remember that if the circlips should come
adrift or if one is omitted, the cylinder barrel may be
seriously damaged.
Before attempting to replace the cylinder barrel over
the piston, smear the piston sides generously with
clean engine oil. Fit a new gasket and place the barrel
over the piston carefully manipulating the rings into
the base of the bore and seeing that they enter freely
without the application of force. When the barrel is
correctly fitted, replace the cylinder head and gasket.
Note that on early D14 models two cylinder head
gaskets of 0·025" thickness were fitted. Later these
were replaced by a single gasket of 0·050" thickness.
Always check the gasket thickness when fitting as two
must be fitted if of the thinner type. Fit the washers
and nuts on to the fixing studs and tighten the nuts in
diagonal order so as to avoid distortion.
Examine the sparking plug and refit if sound. Check
that the rubber sealing ring on the carburetter flange is
undamaged and finally reconnect the exhaust pipe,
carburetter, petrol pipe and re-fix the petrol tank.
REMOVAL OF ENGINE
Turn off the fuel supply and disconnect the fuel pipe
union at the carburetter float chamber. Do not attempt
to pull the pipe off the union unless it is going to be
renewed. The air cleaner hose should now be
disconnected from the carburetter. Undo the two nuts
securing the carburetter to the cylinder flange studs
and tie the unit out of the way.
Using a suitable "C"-spanner, release the exhaust
pipe union nut from the cylinder barrel.
Summary of Contents for D14/4 BANTAM SUPREME D14/4 BANTAM SPORTS
Page 3: ...Page 3 ...
Page 4: ...Page 4 ...
Page 5: ...Page 5 ...
Page 28: ...D14 4 ENGINE B2 FIG B1 Engine exploded ...
Page 47: ...D14 4 CARBURETTER C2 FIG C 1 Concentric carburetter exploded ...
Page 55: ...D14 4 FRAME AND FITTINGS D2 FIG D1 Frame dimensions ...
Page 100: ...D14 4 ELECTRICAL SYSTEM G14 FIG G8 Wiring diagram all models except Bushman Pastoral ...
Page 101: ...D14 4 ELECTRICAL SYSTEM G15 FIG G9 Wiring diagram Bushman Pastoral models ...
