O.S. Engines 21TM - Manual (Page 13)

24
Installing Dust Caps
When storing the engine, install the cap on
the exhaust port, carburetor, etc. to prevent
dust from entering the engine.
5. Finally, when cleaning the exterior of the
engine, use only methanol. Do not use
gasoline, kerosene or any solvent that might
damage the silicone fuel tubing.
Caution:
The rear crankshaft bearing of this engine
uses a special plastic retainer. If the front
housing needs to be heated to remove or
replace the bearing, do not allow the
bearing to exceed 120˚C (248˚F), otherwise
it may be damaged and rendered
unserviceable.
Dirt and dust may lodge in marked places.
(Optional extra)
25
CHECKING THE ENGINE
If the engine suffers a loss of performance
after a long period of running it may be due to
the wearing of parts. It is suggested that the
worn parts be replaced when the following
symptoms are detected.
Engine sound changes and easily overheats.
Power has dropped considerably.
Idle is unstable and/or engine tends to stop
at idle.
In most cases, ball bearings, cylinder & piston
assembly, connecting rod and/or crankcase have
become worn out or abnormal. Check the
parts carefully and replace them if necessary.