User Manual
2
Remember that your engine is not a " toy ", but a highly 
efficient internal-combustion machine whose power is 
capable of harming you, or others, if it is misused or 
abused. As owner, you, alone, are responsible for the safe 
operation of your engine, so act with discretion and care at 
all times.
If at some future date, your O.S. engine is acquired by 
another person, we would respectfully request that these 
instructions are also passed on to its new owner.
WARNINGS
These cover events which might involve serious (in 
extreme circumstances, even fatal ) injury.
NOTES
These cover the many other possibilities, generally less 
obvious sources of danger, but which, under certain 
circumstances, may also cause damage or injury.
SAFETY INSTRUCTIONS AND 
WARNINGS ABOUT YOUR 
O.S. ENGINE
The advice which follows is grouped under two 
headings according to the degree of damage or danger
which might arise through misuse or neglect.
WARNINGS
Never touch, or allow any object to come into 
contact with, the rotating propeller and do not 
crouch over the engine when it is running.
A weakened or loose propeller may disintegrate or be thrown 
off and, since propeller tip speeds with powerful engines may 
exceed 600 feet(180 metres) per second, it will be understood 
that such a failure could result in serious injury, (see 'NOTES' 
section relating to propeller safety).
Model engine fuel is poisonous. Do not allow it to 
come into contact with the eyes or mouth. Always 
store it in a clearly marked container and out of 
the reach of children.
Model engine fuel is also highly flammable. Keep it 
away from an open flame, excessive heat, sources 
of sparks, or anything else which might ignite it. 
Do not smoke or allow anyone else to smoke, near 
to it.
Never operate your engine in an enclosed space. Model 
engines, like automobile engines, exhaust deadly carbon-
monoxide. Run your engine only in an open area.
Model engines generate considerable heat. Do 
not touch any part of your engine until it has 
cooled. Contact with the muffler(silencer), 
cylinder head or exhaust header pipe, in 
particular, may result in a serious burn.
3
NOTES
This engine was designed for model aircraft. Do not attempt to use it for any other purpose.
Mount the engine in your model securely, following the manufacturers' recommendations, using appropriate 
screws and locknuts.
Be sure to use the silencer (muffler) supplied with the engine. Frequent exposure to an open exhaust may 
eventually impair your hearing. 
Such noise is also likely to cause annoyance to others over a wide area.
If you remove the glowplug from the engine and check its condition by connecting the battery leads to it, do not hold 
the plug with bare fingers.Use an appropriate tool or a folded piece of cloth.
Install a top-quality propeller of the diameter and pitch specified for the engine and aircraft. Locate the propeller on 
the shaft so that the curved face of the blades faces forward-i.e. in the direction of flight. Firmly tighten the propeller 
nut, using the correct size wrench.
Always check the tightness of the propeller nut and retighten it, if necessary, before restarting the engine, 
particularly in the case of four-stroke-cycle engines. If a safety locknut assembly is provided with your engine, 
always use it. This will prevent the propeller from flying off in the event of a "backfire", even if it loosens. Also, 
check the tightness of all the screws and nuts before restarting the engine.
If you install a spinner, make sure that it is a precision made product and that the slots for the propeller blades 
do not cut into the blade roots and weaken them.
Discard any propeller which has become split, cracked, nicked or otherwise rendered unsafe. Never attempt to 
repair such a propeller: destroy it. Do not modify a propeller in any way, unless you are highly experienced in tuning 
propellers for specialized competition work such as pylon-racing.










