O.S. engine max-21RG-M Owner's Instruction Manual page 16

Warm up the engine by running it at around idling
setting for a while after starting,
As with the engine of a full size boat. High r.p.m.
operation without warming up will shorten engine
life or damage it.
Leaving the Needle-Vale set at the starting setting
of 2-1/2 turns open, run the boat several times with
the throttle fully open until at least three full tanks of
fuel have been consumed. (It should be noted, at
this stage, it may not be possible for the engine to
idle reliably because f the over-rich setting of the
Needle-Valve.)
This completes the initial running-in stage. For the
remaining period of running-in, refer to the
adjustment procedures detailed later. The boat will
need to be run or about 10 tanks of fuel to complete
the running-in period.
Note!
If as a result of your boat being capsized, the
engine takes in water, remove the glowplug,
invert the engine and eject water by carefully
turning the flywheel, first by hand and then with
the electric starter. Make every effort to ensure
that no water remains in the engine before
attempting to restart it, or it may be damaged by
an hydraulic lock.
To ensure that any traces of water (which may
also cause internal rusting if not dealt with) are
flushed out, use an appropriate water-displacing
spray lubricant.
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