O.S. engine max-21RG-M Setup guide

It is of vital importance, before attempting to
operate your engine, to read the general
'SAFETY INSTRUCTIONS AND WARNINGS'
section on pages 2-5 of this booklet and to strictly
adhere to the advice contained therein.
●Also, please study the entire contents of this
instruction manual, so as to familiarize yourself
with the controls and other features of the
engine.
Keep these instructions in a safe place so that
you may readily refer to them whenever
necessary.
It is suggested that any instructions supplied
with the vehicle, radio control equipment, etc.,
are accessible for checking at the same time.
●
●

CONTENTS
SAFETY INSTRUCTIONS AND
WARNINGS ABOUT YOUR O.S. ENGINE
INTRODUCTION, BASIC ENGINE PARTS
INSTALLATION
NOTES CONCERING
THE RECOIL STARTER
GLOWPLUG
TOOLS, ACCESSORIES, etc.
CARBURETTOR CONTROLS
STARTING & INITIAL
RUNNING-IN('Breaking-in)
ADJUSTMENT
2
~
5
6
7
~
8
8
~
9
9
~
10
10
~
11
13
~
15
16
~
17
18
~
19
20
~
21
22
28
CARE AND MAINTENANCE
CHECKING OF THE ENGINE
TROUBLE SHOOTING WHEN THE
ENGINE FAILS TO START
ENGINE EXPLODED VIEW
ENGINE PARTS LIST
CARBURETTOR EXPLODED VIEW
& PARTS LIST
O.S. GENUINE PARTS &
ACCESSORIES
THREE VIEW DRAWING
MEMO
12
19
23
24
25
26
~
27
1

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.
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.
SAFETY INSTRUCTIONS AND WARNINGS ABOUT YOUR O.S. ENGINE
The advice which follows applies basically to ALL MODEL ENGINES and is
grouped under two headings according to the degree of damage or danger
which might arise through misuse or neglect.
WARNINGS NOTES
These cover events which
might involve serious (in
extreme circumstances, even
fatal) injury.
These cover the many other
possibilities, generally less obvious
sources of danger, but which, under
certain circumstances, may also
cause damage or injury.
2

WARNINGS
Model engine fuel is poison-
ous.Donotallowittocomeinto
contactwiththeeyesormouth.
Always store it in a clearly
markedcontainerandoutofthe
reach of children.
Modelenginefuelisalsohighly
flammable. Keep it away from
open flame, excessive heat,
sources of sparks, or anything
else which might ignite it. Do
notsmokeorallowanyoneelse
to smoke, near to it.
Never operate your engine in an en-
closed space. Model engines, like auto-
mobile 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.
•
•
•
•
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.
•
3

This engine was designed for model boats.
Donotattempttouseitforanyotherpurpose.
Mount the engine in your model securely,
following the manufacturers' recommenda-
tions, using appropriate screws and lock-
nuts.
Fit an effective silencer (muffler). Frequent
close exposure to a noisy exhaust
(especially in the case of the most powerful
high-speed engines) may eventually impair
your hearing and such noise is also likely to
causeannoyancetoothersoverawidearea.
Take care that the glowplug clip or battery
leads do not come into contact with the
propeller or any other rotating parts. Also
check that the linkage to the throttle arm is
secure.
If your engine does not have a built-in recoil
starter, use an electric starter. The wearing
of safety glasses is also strongly
recommended.
When handling the boat immediately prior to
launching, be especially cautious.
Keep the propeller and other rotating parts
away from you.
NOTES
•
•
•
•
•
•For their safety, keep all onlookers
(especially small children) well back (at
least 20 feet or 6 meters) when preparing
your model for running.
•
4

Adjust the throttle linkage so that the
engine stops when the throttle stick and
trim lever on the transmitter are fully
retarded. Alternatively, the engine may be
stopped by cutting off the fuel supply.
Never try to stop the engine physically.
Warning! Immediately after a glowplug-
ignition engine has been run and is still
warm, conditions sometimes exist whereby
it is just possible for the engine to abruptly
restart if it is rotated over compression
WITHOUT the glowplug battery being
reconnected.
NOTES
•
•
•
•
If your engine is fitted with a recoil starter,
pull the operating handle straight out when
starting the engine, so that the cord does
not rub against the hull or engine.
This will help prevent the cord from being
damaged by abrasion or engine heat.
•
Do not extend the starter cord more than
45cm (18"). Do not abruptly release the
operating handle.
Allow the cord to rewind smoothly while still
holding the handle.
Do not attempt to disassemble the recoil
starter (if fitted). If you do so, the very
strong spring inside will be suddenly
ejected. This can be very dangerous.
5

MAX-21RG-MX
The O.S. "RG Series" is a high-performance
water-cooled marine engine for small radio-
controlled boats, especially sport type hulls.
A companion model, the MAX-21RG-MX in-
corporating a recoil starter system is also
available.
With this engine, the piston will feel tight
at the top of its stroke when the engine is
cold. This is normal. The piston and
cylinder are designed to achieve a perfect
running clearance when they reach their
normal running temperatures.
We do not recommend running your boat
on the sea, or in any other saltwater
environment. Under such conditions, it is
difficult to prevent the engine from
becoming corroded and, eventually,
inoperative.
NOTE
•
•
Standard accessories
Glow Plug No.8
Flywheel No2E Exhaust Header Pipe
BASIC ENGINE PARTS
Carburettor
Type 20J
Water Cooled Head
Starter Handle
Recoil Starter
Assembly No.5
Beam Mount
Crankcase
Cranshaft
Glow Plug No.8
INSTALLING THE GLOWPLUG
Install the washer on the
glowplug and insert carefully
into cylinder-head, making sure
that it is not cross-threaded
before tightening firmly.
Glow plug
Washer
6

Insert the taper collet on the crankshaft, taking care
not to push the crankshaft to the cover plate end.
Select the screw
holes according to
the model.
INSTALLATION OF THE CARBURETOR
As delivered, the engine has its carburetor lightly
fitted into its intake boss. Secure it as follows.
Loosen the retainer screw, rotate the carburetor to
its correct position and make sure that it is pressed
well down into the intake boss, compressing the
rubber gasket, before retightening screw.
Rotate the retainer screw gently until it stops, then
tighten a further 90-120˚.
Do not overtighten the screw as this will damage
the carburetor body.
1.
2.
Rotate the retainer nut
gently until it stops. Tighten a further 90-120˚
Crankshaft
Flywheel
Taper Collet
INSTALLATION OF THE FLYWEEL
INSTALLATION OF THE
EXHAUST HEADER PIPE
7

INSTALLATION
Make sure that the engine mounting beams in the
hull are parallel, with their top surfaces in the same
plane. If they are not, the engine will not rest firmly
as the engine mounting faces (undersides of the
mounting lugs) are precision machined to be flat
and in the same plane. Poor installation may not
only cause vibration, erratic running and loss of
performance, but may also damage the engine
itself by deforming the crankcase, cylinder, etc.
The mounting beams and adjacent hull structure
should be as rigid as possible so that the engine
may develop its full performance. Use 3mm steel
screws, such as Allen socket-head type, with
locknuts, for bolting the engine to the mounting
beams.
If the holes in the mounting beams do not align
exactly with the engine's mounting lugs, enlarge
them slightly with a needle file so that the mounting
screws pass through the holes smoothly without
being forced.
1.
2.
3.
Chamfer inside edges of bearers.
NOTES CONCERNING THE RECOIL STARTER
REMINDER!
◆Do not attempt to disassemble the recoil
starter. If you do so, the very strong spring
inside will be suddenly ejected. This can be
very dangerous.
◆Do not extend the starter cord more than
45cm(18"). Do not abruptly release the
operating handle. Allow the cord to rewind
smoothly while still holding the handle.
◆Pull the operating handle straight out when
starting the engine, so that the cord does not
rub against the vehicle body or engine.This
will help prevent the cord from being damaged
by abrasion or engine heat.
8

◆
◆
NOTE: Because, in the interests of personal
safety, dismantling of the starter mechanism
isstrongly discouraged, the Recoil Starter is
available for replacement only as a pre-
assembled unit. However, some related parts,
such as Starting Shaft and Rear Adaptor, are
obtainable separately. (See Parts List.)
Try to avoid spilling fuel over the starter unit
and its cord. Some fuels have a detrimental
effect on these parts.
The starter prevents the engine from being
rotated in the wrong direction. The unit will be
damaged if you attempt to force the flywheel
in the opposite direction (i.e. clockwise when
viewed from the crankshaft end).
GLOWPLUG
Since the compatibility of the glowplug and fuel can
have a marked effect on performance and reliability, it
is suggested that the user selects the R/C type plug
found most suitable after practical experiments.
Generally, for a fuel containing about 30%
nitromethane, a medium heat range glowplug will be
suitable.
The role of the glowplug
With a glowplug engine, ignition is initiated by the
application of a 1.5-volt power source. When the
battery is disconnected, the heat retained within the
combustion chamber remains sufficient to keep the
plug filament glowing, thereby continuing to keep the
engine running. Ignition timing is 'automatic': under
reduced load, allowing higher rpm, the plug becomes
hotter and, appropriately, fires the fuel/air charge
earlier; conversely, at reduced rpm, the plug become
cooler and ignition is retarded.
For higher nitro fuel, a cold rated plug may be
required, whereas, for lower nitro fuel, a hot rated
plug may be best. However, the O.S. No.8 glowplug
may be employed irrespective of the nitro content of
the fuel.
9

¡
When to replace the glowplug
Filament surface has roughened and turned white.
¡
¡Engine tends to cut out when idling.
¡
Apart from when actually burned out, a plug may
need to be replaced because it no longer delivers its
best performance, such as when:
Do not run the engine too lean and do not leave the
battery connected while adjusting needle.
Foreign matter has adhered to filament or plug
body has corroded.
Filament coil has become distorted.
Starting qualities deteriorate.
¡
¡
Glowplug life
Install a plug suitable for the engine.
¡
¡
Particularly in the case of very high performance
engines, glowplugs must be regarded as expendable
items. However, plug life can be extended and engine
performance maintained by careful use, i.e.:
Use fuel containing a moderate percentage of
nitromethaneunlessmoreisessentialforracingevents.
TOOLS, ACCESSORIES, etc.
The following items are necessary for operating the
engine.
FUEL
When the brand of fuel is changed, or the nitro content
increased, it is advisable to repeat the running-in
procedure referred to in the RUNNING-IN paragraphs.
For consistent performance and long engine life, it is
essential to use a good quality fuel containing NOT
LESS THAN 18% lubricant. Please note that with high-
nitro fuels, although power may be increased for
competitionpurposes, glowplug elements do not last as
long and engine life will be shortened.
REMINDER!
Model engine fuel is poisonous. Do not allow
ittocomeintocontactwiththeeyesormouth.
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 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.
10

PROPELLER
Use well balanced propellers only. As the ideal
diameter, pitch and shape vary according to the size,
weight and type of model, final selection can be made
after practical experiment. As a starting point,
suggested propeller diameter is 40-44mm with a
pitch/dia ratio of 1.0-1.6 for Vee type hulls.
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.
REMINDER!
LONG SOCKET WRENCH
SILICONE FUEL LINE
This is required for the
connection between the fuel
tank and engine, also for the
water-cooling system.
ELECTRIC STARTER AND STARTER BATTERY
Use a 12-volt electric starter
with suitable battery for starting
the engine.(21RG-M)
BATTERY INTEGRATED GLOWPLUG HEATER
Commercialy available handy glowplug
heater in which the glowplug battery
and battery leads are integrated.
Recommended for easy removal and
replacement of the angled and
recessed glowplug, the O.S.Long
Socket Wrench incorporates a
special grip.
FUEL PUMP
For filling the fuel tank, a simple, poly-
ethylene "squeeze" bottle, with a suit-
able spout, is required.
11

CARBURETTOR CONTROLS
The Needle Valve:
When set to produce maximum power at full throt-
tle, this establishes the basic fuel/air mixture
strength. This is then maintained by the carburet-
tor's automatic mixture control system to cover the
engine's requirements at reduced throttle settings.
The Mixture Control Valve (Mixture Control Screw):
For adjusting the mixture strength at part-throttle
and idling speeds, to obtain steady idling and
smooth acceleration to medium speeds. The Mix-
ture Control Valve has been factory set for the ap-
proximate best result. First, run the engine as re-
ceived, and re-adjust the Mixture Control Valve only
when necessary.
Two adjustable controls are provided on this carburettor.
●
●
Needle-Valve
Mixture Control Valve
(Mixture Control Screw)
Throttle Lever
Fuel Inlet
Rotor Guide Screw
■REALIGNMENT OF MIXTURE CONTROL VALVE
In the course of making carburettor adjustments, it is
just possible that the Mixture Control Valve may be
inadvertently screwed in or out too far and thereby
moved beyond its effective adjustment range.
Its basic setting can be reestablished as follows :
Nozzle
Throttle Rotor Hole
Mixture Control Valve
(Mixture Control Screw)
The basic ( factory ) setting is
as shown in the main sketch, i.
e. with the shoulder portion 'A'
exactly at a tangent to the throt-
tle rotor hole. To return the Mix-
ture Control Valve to its original
position, first screw in the Mix-
ture Control Valve, while look-
ing into the rotor hole.
Then gradually unscrew the
Mixture Control Valve until 'A' is
precisely tangential to the rotor
hole (i.e. so that 'A' and 'B' are
superimposed) as in the main
sketch.
12

Set the needle-valve. Turn the needle clockwise
slowly, without forcing, until it stops.
Then, reopen the needle-valve 2-1/2turns counter-
clockwise.
Open the throttle very slightly:
Turn needle-valve clockwise to
close (for leaner mixture)
Turn needle-valve counterclock-
wise to open (for richer mixture)
This is to avoid unnecessarily
high revolutions when the en-
gine starts.
MarkClose
Open
STARTING & INITIAL RUNNING-IN('Breaking-in')
For long life and high perfomance, every engine
needs to be 'run-in' or 'broken-in'. With care, running-
in of the engine can be carried out with it installed in
the boat. Be sure to use a muffler-pressurized fuel
system.
◆
◆
When starting the engine, put the hull on a stand, etc.
out of the water.
■In case of the 21RG-M
◆Priming
Turn the flywheel by hand to draw the fuel to the
fuel inlet.
Turn the flywheel two more revolutions to draw the
fuel inside the engine.
•
•
•
NOTE (IMPORTANT)
The quantity of fuel drawn into the engine by
priming is an important factor in starting the
engine successfully. When the engine is being
started for the first time, turn the flywheel two
revolutions after fuel reaches the fuel inlet, as
described above. However, when re-starting the
engine immediately after a run, one revolution, or
even no priming at all may be required. The
engine's requirements will be quickly learned with
experience.
Open the throttle fully and place your finger over
the carburetor to choke intake.
13

Do not apply the starter to a flooded engine and
never place your finger over the carburettor in-
take when using the starter. This may cause an
hydraulic lock and bend the connecting-rod.
To stop the engine, fully close the throttle to cut off
air supply.
Warning:
◆
◆
◆
■In case of the 21RG-MX
Take the same procedure as
the 21RG-M to the point of
"Heat the glowplug by
connecting the battery
leads".
Pull the starter handle
briskly straight out several
times to start the engine.
•
•
Starter Handle
Heat the glowplug by connecting the battery leads.
Make sure that the direction of rotation of the
electric starter is correct, namely, clockwise.
If necessary, reverse leads on battery to provide
clockwise rotation.
Hang the starter belt over the flywheel and starter
and depress the starter switch for one or two
seconds. Repeat if necessary. When the engine
fires, withdraw the starter immediately.
◆
PRECAUTIONS
When starting the engine,
the hull is off the water and
the engine is run with no
load, and with even below
half throttle engine r.p.m.
come high. Prolonged
running with this condition may result in the
seizure of the connecting rod and crank pin.
Never run the engine with high r.p.m. (never open
the throttle beyond the starting setting) with no
load (i.e. the hull is off the water).
14

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.
Warm up the engine by running it at around idling
setting for a while after starting, 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.
◆
◆
◆
15

ADJUSTMENT
Running the engine with the boat out of the water,
without load and without cooling water, will seri-
ously damage it, due to overheating. Therefore,
always lower the boat into the water immediately
after the engine has been started, so as to pre-
vent over-speeding and to allow cooling water to
be forced up to the cylinder-head. Having carried
out the initial running-in (''breaking-in'') proce-
dure as described before, complete the running-
in as follows:
WARNING :
Fig.-1
1.
2.
3.
4.
Open the throttle slightly
from the idling position
and start the engine,
following the procedure
described previously.
Lower the boat into the water, gradually open the
throttle and run the boat straight ahead for 20 to 30
metres at full throttle. Now return the model and
close the needle-valve 20 to 30
°
. Repeat the run,
taking note of the improvement in speed.
Continue with further runs, gradually closing the
needle-valve (20 to 30° at a time) until no further
increase in speed is obtained.
If the needle-valve is closed beyond the optimum
setting, the model will slow down, accompanied by
visibly diminished exhaust smoke. In this case,
immediately throttle down and return the model to
shore. Re-open the needle-valve approximately
one-half turn and repeat the runs until the
optimum needle setting is found.
5.
6.
Aim to have the model achieving its highest
performance after the engine has consumed about
one liter of fuel. Having found the optimum needle-
valve setting, make a note of the number of turns
necessary to quart this from the closed position.
With the engine run-in and the optimum needle-
valve setting determined, the mixture control valve
should be checked as follows:
16

7. Launch the boat and gradually open the throttle to
its fullest extent. If at this point, the engine puffs
out a good deal of smoke and does not accelerate
smoothly and rapidly, it is a sign that the idling
mixture is too rich. Therefore, turn the mixture
control screw clockwise 45 to 60°. Repeat the run
and recheck the result.
8. If, on the other hand, the idling mixture is too lean,
the engine is likely to speed up momentarily, then
cut out abruptly when the throttle is re-opened. In
this case, first turn the mixture control screw
counter-clockwise 90° to make sure that the
mixture has become richer, then make
incremental adjustments, each way, until an
acceptable balance between rich v.lean settings is
achieved. Carry out these adjustments patiently
under actual running conditions, until the engine
responds quickly and positively to throttle
movements. Use a small screwdriver to adjust the
mixture control valve via its slotted screwhead in
the center of the outer end of the throttle rotor.
WARNING :
Note :
Remember that, if the engine is operated with the
fuel/air mixture slightly too lean, it will overheat and
run unevenly or cut out. As with all engines, it is
wise to set both valves a little on the rich side of the
best rpm setting, as a safety measure. When the
best balance of mixture adjustments has been
determined and, especially as the engine becomes
fully run-in, it will probably be found that the idling
speed has increased. Readjust the throttle opening
by means of the trim lever on the transmitter, so
that the lowest idling speed, without risk of stalling
the engine, may be obtained.
10.
For safety reasons, it is advisable to stop the
engine before carrying out adjustments to the
Mixture Control Screw.
Once the correct carburettor settings have been
established, it should be unnecessary to alter
them. Such slight Needle-Valve readjustments as
may be required to compensate for variations in
atmospheric conditions will not normally affect the
other two controls. Slight readjustments may be
necessary for optimum performance if different
types of fuel, glowplugs or propellers are used.
With the optimum mixture control valve position,
light smoke is visible during high-speed running
and engine r.p.m. increase smoothly during
acceleration.
9.
17

CARBURETTOR CLEANLINESS
Proper functioning of the carburettor depends on its
small fuel orifices remaining clear. The minute
particles of foreign matter that are present in any fuel,
can partially obstruct these orifices and upset mixture
strength so that engine performance becomes erratic
and unreliable. It is recommended that fuel is passed
through a filter when the tank is filled and that a good
in-line filter is installed between the fuel tank and
carburettor and, furthermore, that this filter is
frequently cleaned to remove dirt and lint that
accumulate on the filter screen. Finally, occasionally
remove the needle-valve holder from the carburettor
as shown below and extract any remaining foreign
matter that may have lodged in the location shown.
Remove this with an
8mm spanner
Dirt and fibrous matter
mostly accumulate here
CARE AND MAINTENANCE
To ensure that you obtain long life and peak
performance from your engine, observe the follow ing.
As previously observed, foreign matter in the fuel
can cause problems. Therefore:
rinse out the fuel tank with methanol or fuel before
installing it.
Install a fuel filter to the fuel delivery tube between
tank and carburettor.
Install a fuel filter to the outlet of your squeeze
bottle, or to the pump inlet if you use a manual or
electric pump. *
do not leave your fuel container open needlessly.
●
1
●
●
●O.S. 'Super-Filter' (L) is available, as optional ex-
tra,to deal with this problem. To fit this filterto the
outlet tube inside your refuelling container, will pre-
vent the entry of foreign material into the fuel tank.
✽
Do not forget to clean the filters regularly to
remove dirt and lint that accumulate on the filter
screens. Also, clean the carburettor itself
occasionally.
2
18

At the end of each operating session, drain out any
fuel that may remain in the fuel tank. Afterwards,
energize the glowplug and try to restart the engine,
to burn off any fuel that may remain inside the en-
gine. Repeat this procedure until the engine fails to
fire. Leaving fuel residues within the engine can
result in difficult starting after a period of storage. It
may also cause corrosion. To reduce such risks, it
is helpful to inject some corrosion inhibiting oil into
the engine's air intake. Rotate the engine many
times to distribute the oil to all the working parts.
3
Drain the water remaining in the water cooling
head, and wash out with methanol, then inject cor-
rosion-inhibiting or moisture-displacing oil.
When cleaning the exterior of the engine, use me-
thanol or kerosene. Do not use gasoline or any
solvent that might damage the silicone fuel tubing
or any plastic parts of the boat hull.
4
5
6When the engine is not in use remove the glow-
plug and rinse out the interior with kerosene (not
gasoline), by rotating the crankshaft. Shake out re-
sidue, then inject light machine-oil through the plug
hole again rotating the shaft to distribute the pro-
tective oil to all working parts.
7
8
In the event of water having entered the cylinder,
crankcase, etc., refer to the procedures recom-
mended in the footnote to "running-in" section.
Avoid unnecessary disassembly of your engine.
After a long use, the engine will not develop the
standard performance due to wear of parts. It is
suggested to replace the parts, such as ball bearings,
connecting rod, cylinder & piston assembly and
crankcase, as necessary after checking when the
following symptoms are found.
CHECKING OF THE ENGINE
Idling gets unstable and/or the engine stops at
idling.
Engine sound changes and the engine tends to
overheat.
Power drops extremely.
●
●
●
19