O.S. Engines 21VG-PX - Manual (Page 4)

6
Piston
Cylinder Liner
Crankshaft
ENGINE CONSTRUCTION
With this engine, the piston
will feel tight at the top of its
stroke (TDC) when the engine
is cold.
This is normal.
The cylinder bore has a
slight taper.
The piston and cylinder are
designed to achieve a perfect
running clearance when they
reach operating temperature.
Near TDC
Slight taper
When the engine is cold. When the engine is hot.
7
Notes when starting the engine
Do not over-prime.
This could cause a hydraulic lock
and damage the engine on
application of the electric starter or
recoil starter.
If over-primed, remove glowplug,
close the needle-valve and apply
starter or pull recoil starter to
pump out surplus fuel.
Cover the head with a rag to
prevent any pumped out fuel from
getting into your eyes.
Remove the glowplug.
Pump out surplus fuel.
Install the glowplug.