A.J.S. 16MS, Instruction Book

Page: 36 / 94

TO REMOVE AND REPLACE THE OIL PUMP PLUNGER IF
A N D W H E N NECESSARY ONLY
Remove
Lower end of rocker box oil feed pipe by unscrewing union nut.
Both oil pump end caps.
Oil pump plunger guide screw with pin. (See illustration 12.)
Oil pump plunger, by pushing at front and extracting from rear end of its housing.
Replace by :
Reversing above procedure.
NOTE—Remember there Is a paper washer under each oil pump end cap and, when
fitting a new paper washer to the front cap, ensure the oil -passage in the
front cap is not obstructed by the paper washer.
Important
Never attempt to insert the guide screw unless both oil pump end caps are
removed, when by moving the pump plunger to and fro with the fingers it can be
felt when the pin engages with the groove in the plunger. When correctly
fitted the shoulder on the screw will abut against the boss into which it fits.
(See illustration 12.)
Do not under any circumstances revolve the engine until quite certain that the
pin is correctly positioned otherwise damage will inevitably result.
Securely tighten the screw to prevent any possibility of it unscrewing in use.
Under no circumstances must either the pump plunger or guide screw be
disturbed in ordinary routine maintenance.
OVERSIZE PARTS AND RE-BORING CYLINDER BARREL
Pistons and rings, .020" and .040" larger than standard, are available. These degrees
of oversize make it essential for the cylinder barrel to be re-bored to accommodate them.
We can provide that service at prices quoted In the Spares List.
On the 350 c.c. the cylinder standard bore is 2.7187
± .0005". The 500 c.c. cylinder
standard bore is 3.250 ± .0005".
When the wear at the top of the barrel reaches .008" the barrel should be bored out
.020" oversize and a new oversize piston and rings fitted.
Crankpin rollers .001" larger than standard can be supplied. We recommend only
skilled mechanics should fit these because it is almost general that the big-end journals
and sleeves require " lapping " to ensure a correct fit.
REMOVING SPARKING PLUG
Always exercise the greatest care to avoid thread seizure when removing a sparking
plug. If any resistance is felt, apply paraffin. Before replacing plug, it is desirable to
coat the thread with " Oil Dag " or Graphite paste. This will guard against seizure
upon subsequent removal.
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