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.
SAFETY INSTRUCTIONS AND
WARNINGS ABOUT YOUR O.S. ENGINE
ENGINE CONSTRUCTION, NOTES ON
INSTALLING FLYWHEEL, NOTES WHEN
APPLYING AN ELECTRIC STARTER
INSTRUCTIONS,
TOOLS, ACCESSORIES, etc.
BASIC ENGINE PARTS, INSTALLATION OF
THE ACCESSORIES SUPPLIED,
INSTALLATION OF REPLACEMENT PARTS
INSTALLATION
GLOWPLUG, CARBURETOR CONTROLS
STARTING THE ENGINE &
RUNNING-IN ('Breaking-in)
CONTENTS
2-5
6-8
9-11
12-14
15
16-18
19-22
FINAL ADJUSTMENT
CARBURETOR CLEANLINESS,
CARE AND MAINTENANCE
CHECKING THE ENGINE, GUARANTEE
TROUBLE SHOOTING
ENGINE EXPLODED VIEWS &
PARTS LIST
CARBURETOR EXPLODED VIEW &
PARTS LIST
O.S. GENUINE PARTS & ACCESSORIES
THREE VIEW DRAWING
1
23-24
25-26
27
28-31
32-33
34-35
36-37
38
SAFETY INSTRUCTIONS AND WARNINGS ABOUT YOUR O.S. ENGINE
Remember that your engine is not a "toy", but a highly efficient internalcombustion 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.
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
!
These cover events which
might involve serious (in
extreme circumstances, even
fatal) injury.
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.
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
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.
NOTES
!
These cover the many other
possibilities, generally less obvious
sources of danger, but which, under
certain circumstances, may also
cause damage or injury.
2
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 boats.
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.
Install 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
cause annoyance to others ov er a wide area.
For their safety, keep all onlookers
(especially small children) well back (at
least 20 feet or 6 meters) when preparing
your model for running.
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.
Before starting the engine, always check the
tightness of all the screws and nuts especially those of joint and movable parts such as
throttle arm. Missing retightening the loose
screws and nuts often causes the parts
breakage that is capable of harming you.
4
NOTES
!
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 glowplugignition 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.
5
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
Piston
Cylinder Liner
Crankshaft
Slight taper
Notes on installing flywheel
Do not use a tool which
locks piston when
installing a flywheel, or
top of the piston may
be damaged. Also, do
not insert a screw
driver or the similar
into the exhaust port.
It is recommended to use Crankshaft
Clamp 1521 (Code No.71530200) available
as an optional tool.
It is made of durable engineering plastic
and locks the crankshaft without risk of
damage to any part of the engine.
When the engine is cold.
6
Application is as follows:
Remove the crankcase rear cover plate from the
engine and rotate the crankshaft to the bottom
dead center (BDC) position.
Insert the crankshaft clamp so that its grooved
portion surrounds the crankpin and lower end of
the connecting rod and securely tighten the fan
or clutch onto the crankshaft.
When the engine is hot.
BDC position
Rotate the crankshaft so that the
connecting rod comes to this position.
Insert this groove onto
the connecting rod.
7
NOTES WHEN APPL YING
AN ELECTRIC STARTER
Do not over-prime. This could
cause a hydraulic lock and damage
the engine on application of the
electric starter.
If over-primed, remove glowplug,
close needle-valve and apply
starter to pump out surplus fuel.
Cover the head with a rag to
prevent pumped out fuel getting
into your eyes.
We do not recommend running your boat
NOTE
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.
8
INSTRUCTIONS
The
MAX-
21VZ-M is designed expressly
for 21 class boat racing. P7 Turbo plug
is supplied with the engine and also
water cooled plug cap is installed,
which improves power output, fuel
consumption and durability. Big bore
of 10mm 21D carburetor copes with
high nitro fuel. This engine offers high
racing potential maintaining O.S. traditional easy-to-handle characteristics.
Standard accessories
Glow Plug P7 For T-type head
(Turbo head) 1piece
Cylinder-head gasket
(0.1mm) 1 sheet
Dust Cap 3, 16, 18
1piece each
(Medium Type)
Water Cooled Plug Cap
Flywheel No.2K Assembly
(Taper Collet,)
(Installed)
Exhaust Seal Ring 1piece
Head Gaskets
The engine is installed a 0.2mm thick head
gasket. If you find the following symptoms
after running the engine, add a 0.1mm thick
gasket supplied.
With the appropriate needle setting, engine
r.p.m. drop and power loses during running.
Glow plug burns out frequently.
Composition and proportion of lubricant in the
fuel may affect the symptoms.
9
TOOLS, ACCESSORIES, etc.
The following items are necessary for operating the engine.
Items necessary for starting
FUEL
Generally, it is suggested that the user selects a fuel
that is commercially available for model two-stroke
engines and contains 10-30% nitromethane. As a
starting point, we recommend a fuel containing 20%
nitromethane, changing to a fuel containing more
nitro if necessary. 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. Please note that with
high-nitro fuels, although power may
be increased for competition purposes,
glowplug elements do not last as long
and engine life will be shortened.
REMINDER!
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.
10
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.
GLOWPLUG IGNITER
Commercialy available handy glowplug
heater in which the glowplug battery
and battery leads are integrated.
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
41-43mm with a pitch/dia ratio of 1.0-1.1 for indrive Vee type hulls, 40-45mm with a pitch/dia.
ratio of 1.2-1.6 for out-drive Vee type
hulls and 44-46mm with a pitch/dia.
ratio of 1.4-1.6 for hydroplanes.
NOTE
Never use a propeller that has even a
slight damage.
REMINDER!
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.
STARTER BELT
Necessary for starting the engine.
It is suggested to keep a starter rope as a
reserve.
ELECTRIC STARTER AND STARTER BATTERY
Use a 12-volt electric starter
with suitable battery for starting the engine.
SILICONE TUBING
This is required for the connection between the
fuel tank and engine, also for the water cooling
system. Inner dia. of 2.3-2.5mm
and outer dia. of 5-5.5mm would be
suitable.
SUPER FILTER (L)
Fit a filter to the outlet tube of your
refuelling container to prevent entry of
foreign matter into the fuel tank.
TOOLS
HEX SCREWDRIVER
Necessary for engine installation.
1.5mm, 2mm, 2.5mm, 3mm
SCREWDRIVER
Necessary for carburetor adjustments.
No.1, No.2, etc
LONG SOCKET WRENCH WITH PLUG GRIP
Recommended for easy removal and
replacement of the angled and recessed
glowplug, the O.S.Long Socket Wrench
incorporates a special grip.
11
(Option)
BASIC ENGINE PARTS
Water cooled plug cap
NOTE
Install the carburetor, marine head and
water cooled plug cap with suitable
direction according to the model.
Glow Plug P7
Carburetor
Type 21D
Crankshaft
Crankcase
Front Bearing
Water Cooled Head
Exhaust
Cover Plate
Mounting Lugs
INSTALLATION OF THE
ACCESSORIES SUPPLIED
Glow plug and water cooled plug cap
Install the glow plug on the
marine head.
Press the water cooled plug
cap on the head securely.
12
INSTALLATION OF THE FLYWEEL
Insert the taper collet on the crankshaft,
taking care not to push the crankshaft to the
cover plate end.
Then, tighten flywheel on the crankshaft
using the tightening stick supplied or
clamping the crankshaft with Crankshaft
Clamp 1521 available as an optional extra.
Crankshaft
Flywheel
Taper Collet
INSTALLATION OF THE
EXHAUST SEAL RING
Install the exhaust seal
ring supplied.
Exhaust
Seal Ring
INSTALLATION OF THE DUST CAP SET
If the engine is to be stored or out of use for
a while, install the included exhaust and
carburetor dust caps to prevent foreign
matter from entering the engine.
INSTALLATION OF REPLACEMENT
PARTS
CARBURETOR SPACER
Apply epoxy glue or LOCTITE inside the
carburetor spacer.
Install the spacer onto the carburetor body
while rotating it.
Wipe off excess glue coming out of the
spacer with thinner.
Install the carburetor gasket onto the spacer.
13
Epoxy glue
or LOCTITE
INSTALLATION OF CARBURETOR
Carburetor Retainer
Insert the carburetor seal washer onto the
bottom of the carburetor installing hole on the
crankcase.
Insert the carburetor retainer into the position
shown in the sketch and install the carburetor
into the installing hole.
Make sure that the carburetor is inserted
securely to the bottom of the installing hole.
Then, screw in the fixing screw gently until it
stops. Screw in 120-180 degrees further.
Do not fasten further, or the carburetor
spacer will be damaged. 120-180 degrees
further tightening is just enough because the
retainer pinches from the both sides.
Screw in the screw gently until it stops.
Carburetor
Sealing Washer
INSTALLATION
Before installing the engine in the model, clean out
the engine room. Especially if the sand paper and
glass wool residues are not removed completely,
they may be sucked into the engine and damage
the engine.
1.
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
2.
structure should be as rigid as possible so that
the engine may develop its full performance.
Use 3mm steel screws, such as Allen sockethead type, with locknuts, for bolting the engine
to the mounting beams.
Tighten a further
120-180˚
14
Touches here
Chamfer edges
If the holes in the mounting beams do not align
3.
Touches here
File off Cut out
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.
4.
Screws are prone to loosen during flights. Be
sure to use the Lock Washers available as
optional extra or locking glue for slack
prevention.
15
GLOWPLUG
Since the glowplug and fuel combination used may
have a marked effect on performance and reliability, it
would be worthwhile to experiment with different plug
types. An O.S. P7 glowplug is supplied with the
engine. Carefully install plug finger-tight, before final
tightening with the correct size plug wrench.
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.
Glowplug life
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.:
Install a plug suitable for the engine.
Use fuel containing a moderate percentage of
nitromethane unless more is essential for racing
events.
Do not run the engine too lean and do not leave the
battery connected while adjusting the needle.
When to replace the glowplug
Apart from when actually burned out, a plug may
need to be replaced because it no longer delivers its
best performance, such as when:
Filament surface has roughened and turned white.
Filament coil has become distorted.
Foreign matter has adhered to filament or plug
body has corroded.
Engine tends to cut out when idling.
Starting qualities deteriorate.
16
CARBURETOR CONTROLS
Two adjustable controls are provided on this
carburetor.
The Needle-Valve:
For adjusting the mixture strength when the
throttle is fully open.
The Mixture Control Screw:
For adjusting the mixture strength at partthrottle and idle speed, to obtain steady idling
and smooth acceleration to mid speeds.
Mixture Control Screw
(21D)
shown in the sketch. (In case of 30% nitro fuel)
In case of 65% nitro fuel, basic position should
be approximately 45 degrees turned left from
the center. Mixture gets lean when the Mixture
Control Screw is turned right, while mixture
gets rich when the Mixture Control Screw is
turned left. With a model boat, adjustments
vary with combined various factors such as
climatic conditions, fuel, muffler, etc.
Therefore, Mixture Control Screw position
varies with each model and set-up, and it is
normal if the Mixture Control Screw position if
off the center.
Needle Valve
Mixture Control Valve
45
BASIC POSITION OF MIXTURE CONTROL SCREW
(Mixture Control Valve)
As delivered, the Mixture Control screw is
positioned at approximately the center as
Mixture
Control Valve
17
Mixture Control Screw
Lean
Thick
NOTE
As the idle mixture control screw is
installed with LOCTITE, it may initially feel stiff, and it is suggested
to use a littli larger screwdriver. The
screw can be turned only 90 degrees either way. Do not
force to turn further, or it may break or cause trouble.
90 degrees
90 degrees
Type 20G Remote-mounting
Needle Valve Assembly
(Optional parts)
It enables the Needle Valve to be installed
separately from the engine in a position where
(especially with a cowled or enclosed engine) it
may be more accessible for adjustment. (See
sketch.) Install as follows:
Fixing nut
Model or fitting plate
Ratchet spring
Needle
Remote needle holder
Remove the needle-valve holder from the
carburetor and fit the plug screw in its place.
18
Drill a 6mm dia. hole in the required position
on the model and insert the Remote Needle
Valve Assembly. If necessary, install a
suitable mounting plate in the model to
which the Remote Needle Valve Assembly
may be fitted.
Tube length should be kept as short as
possible.
Silicone tubing
Remote needle nut
Plug screw
Remote needle holder
You may also use the
Needle Control Lever in
conjunction with the Remote-mounting Needle
Valve Assembly.
Needle valve
control lever
STARTING THE ENGINE & RUNNING-IN ('Breaking-in)
PRESSURIZED FUEL SYSTEM
The somewhat violent changes of hull attitude
that occur in running, combined with the fact
that, in boats the fuel tank is often located
some distance from the carburetor, means
that fuel 'head' at the carburettor can vary
and upset running.
Therefore,it is recommended that a muffler
pressurized fuel feed system be used.
Before starting the engine, always check
the tightness of all the screws and nuts
especially those of joint and movable
!
parts such as throttle arm. Missing
retightening the loose screws and nuts
often causes the parts breakage that is
capable of harming you.
The following procedure is suitable for these
engines when the fuel containing up to 30%
nitromethane are used.
Fill the tank completely with fuel.
Temporarily remove the glowplug to check
that it glows bright red when energized.
Element glows when energized.
Replace the plug when the
element does not glow or is
burnt out.
Glow Plug Igniter
Turn the needle-valve clockwise slowly until
it stops. This is the fully closed position.
Do not force to turn further.
19
Pliers
Open the Needle-Valve 1.5 turns from the
fully closed position.
Needle Valve
Turn the engine with an electric starter or
recoil starter to draw fuel into the engine.
Deliver fuel into the carburetor.
Fuel tank side
Close
Open
Swith on the transmitter and make sure that
each linkage moves correctly.
Raise the throttle trim 2 or 3 clicks on the
transmitter for easier starting.
Throttle Trim
Fuel
Now connect glowplug battery lead to heat
the plug filament and start the engine.
Start the engine using an electric starter
making sure the engine rotation direction is
correct (counter-clockwise seen from the
crankshaft end).
When the engine starts, first repeat low
speed running and medium speed running
by raising and lowering throttle stick on the
transmitter to warm up the engine.
Aviod high speed running.
20
PRECAUTIONS
When starting the engine, with the hull out
off the water and no load on the engine,
even below half throttle, the engine can
over-rev. Prolonged running at higher
throttle settings can result in seizure of the
connecting rod and crankpin. Never run the
engine with the throttle above the starting
setting with the hull out of the water and no
load on the engine.
Next, disconnect the glowplug battery and
try running the hull on the water. If the
engine stalls, open the throttle fractionally,
but try to keep the engine running as rich as
possible: if it stops because of being
excessively over-rich, close the NeedleValve 30˚ and try again.
Run the hull on the water until one tank of fuel
has been consumed, then close the NeedleValv e 30˚ and run the hull for another full tank
of fuel. Repeat this procedure until 5 more
tanks of fuel have been consumed, during
which time the throttle may be opened for brief
bursts of increased power.
If the engine stops at medium speeds, close
the Mixture Screw 10˚.
21
The position of the needle-valve
when starting the engine.
Needle
TO STOP THE ENGINE
Lower the throttle trim and/or throttle stick on
the transmitter.
Close the needle-valve approx.
30˚ after running the hull for
one full tank of fuel.
Repeat this procedure several
times.
Remember!
If the engine should need to be
disassembled (e.g. for cleaning or minor
parts replacement) it is advisable to return
the Needle-Valve to the original rich,
starting setting and check whether further
running-in time is required before the car is
raced again. In the event of any major
working parts(e,g, piston/cylinder liner
assembly) being replaced, the complete
running-in should be repeated.
Throttle T rim
Throttle Stick
Warning!
Do not touch rotating parts, engine and silencer when stopping the engine as they
become very hot, and contact with them
may result in a serious burn.
22
FINAL ADJUSTMENT
Run the hull (with throttle fully open) over the
longest available straight, in order to observe
the model's speed. Next return the hull to the
starting point, close the Needle-Valve 30˚
and repeat the run, taking note of the
improvement in performance. Continue with
further runs, gradually reducing the NeedleValve setting and aiming to achieve the
highest straight-line speed. Remember,
however, that, if the Needle-Valve is shut
down too far, the engine will overheat and,
accompanied by visibly diminished exhaust
smoke, the model will lose speed. At this
point, throttle down immediately, stop the hull
and reopen the Needle-Valve 30˚.
Having established the optimum NeedleValve setting, check the Mixture Control
Valve setting as follows.
With the engine running, close the throttle
and allow it to idle for about five seconds,
then reopen the throttle fully. If, at this point,
the engine puffs out an excessive amount of
smoke and the hull does not accelerate
smoothly and rapidly, it is probable that the
idle mixture is too rich.
In this case, turn the Mixture Control Valve
clockwise 10˚. If, on the other hand, the
engine tends to speed up momentarily and
then cut out abruptly when the throttle is
opened,the idle mixture is too lean. Correct
this by turning the Mixture Control Valve
counter-clockwise 10˚.
NOTE:
Mixture Control Valve adjustment should
be made in steps of not more than 45-90˚,
carefully checking the effect,on throttle
response, of each small adjustment.
23
Carry out adjustments patiently, under
actual running conditions, until the engine
responds quickly and positively to the
throttle control.
Warning!
Mixture adjustments (whether via the
Mixture Control Valve, or the Needle-Valve)
cannot be made accurately under 'no-load'
conditions, which, in any case, are not
advised, since such operation carries the
risk of seriously damaging the engine
through over-revving and overheating.
With the optimum mixture control position,
light smoke is visible during high speed
running,and the engine rpm increases
smoothly during acceleration. Remember
that, if the engine is operated with the fuel/air
mixture slightly too lean, it will overheat and
run unevenly. As with all engines, it is
advisable to set both needle-valve and
mixture control screw very slightly on the rich
side of the best rpm setting, as a safety
measure.
If the engine runs too fast with the throttle
closed, the throttle stop screw should be
turned counter-clockwise to allow the throttle
opening to be reduced.
Finally, beyond the nominal break-in period,
a slight readjustment toward a leaner needle
setting may be required to maintain
performance.
24
CARBURETOR CLEANLINESS
The correct functioning of the carburetor
depends on its small fuel orifices remaining
clear.
The minute particles of foreign matter that are
present in any fuel can easily 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 carburetor and, furthermore, that this filter
is frequently cleaned to remove dirt and lint
that accumulates on the filter screen.
Finally, occasionally remove the needle-valve
holder from the carburetor as shown in Photo
and extract any remaining foreign matter that
may have lodged in the location shown in the
sketch.
25
Remove this with
an 8mm wrench
Dirt and fbrous matter
mostly accumulate here
CARE AND MAINTENANCE
Engine maintenance is very important for good
running next time. Carry out the followings.
Do not forget to clean the filters regularly to
remove dirt and lint that accumulate on the
filter screens. Also, clean the carburetor itself
occasionally.
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 engine. 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.
Drain the water remaining in the water cooling head, and wash out with methanol, then
inject corrosion-inhibiting or moisture-displacing oil.
When cleaning the exterior of the engine,
use methanol or kerosene. Do not use gasoline or any solvent that might damage the silicone fuel tubing or any plastic parts of the
boat hull.
When the engine is not in use remove the
glowplug and rinse out the interior with kerosene (not gasoline), by rotating the crankshaft. Shake out residue, then inject light machine-oil through the plug hole again rotating
the shaft to distribute the protective oil to all
working parts.
In the event of water having entered the cylinder, crankcase, etc., refer to the procedures recommended in the footnote to
"running-in" section.
Avoid unnecessary disassembly of your engine.
26
CHECKING OF THE ENGINE
After 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.
Idling gets unstable and/or the engine stops
at idling.
Engine sound changes and the engine tends
to overheat.
Power drops extremely.
GUARANTEE
This engine is constructed from the very best
materials available and to the very highest
engineering standards, using the most
advanced precision machinery. However, the
extremely high stresses imposed by car racing
operation under very severe conditions, as
well as stresses which are exacerbated by the
use of powerful fuels containing very high
concentrations of nitromethane, constitute
hazards which are beyond a manufacturer's
control. Accordingly, we regret that it is not
possible to extend our usual warranty terms to
this particular engine -i.e. no guarantee is
offered against material wear, or damage
resulting therefrom, in actual use.
27
TROUBLE SHOOTING
Symptom
Engine fails to fire.
Cause
Fuel tank is empty.
Fuel not reaching the engine.
Glowplug element is burnt out.
Glowplug battery discharged
Clogged fuel filter
Silencer inside is dirty.
Over priming Remove glowplug and pump excess fuel.
Fill the tank with fuel and repeat
Priming procedure.
Replace glowplug.
Recharge or replace the battery.
Clean or replace fuel filter.
Clean inside the silencer.
Corrective action
Fuel tubing is disconnected.
Fuel tubing is kinked, split or has a hole.
Incorrect servo linkage
Reverse rotating direction of electric starter.
Symptom
Engine fires intermittently but does not run.
Cause
Insufficient fuel in the tank. Fill the tank with fuel.
Connect fuel tubing securely.
Check the tubing carefully and replace if necessary.
Connect correctly after setting servo at neutral.
Mare sure it rotates counter clockwise seen
from crankshaft side.
28
Corrective action
Deteriorated glowplug
Clogged fuel filter
Silencer inside is dirty.
Engine overheated
Glowplug battery disconnected too soon.
Air bubbles in fuel
Replace glowplug.
Clean or replace fuel filter.
Clean inside the silencer.
Wait until engine cools.
Do not disconnect plug battery and wait until
r.p.m. become stable.
Install O rings to the tank screws to
prevent bubbles.
29
Symptom
Unstable idle
Cause
Corrective action
Unsuitable glowplug
Unsuitable fuel
Extremely light flywheel Add suitable load.
Silencer is disconnected or has play
Symptom
Not reaching expected peak r.p.m.
Cause
Insufficient warming up or running-in.
Silencer or manifold is not securely connected
or disconnected.
Fuel tubing from tank is split or broken.
Use suggested glowplug in the instructions.
Do not use extremely high nitro or
low oil content fuel.
Install silencer securely.
Set the needle only after warming up.
Complete running-in.
Replace seal ring.
Check the connections and secure them.
Replace the tubing.
30
Corrective action
Symptom
Poor response
Cause
Deteriorated glowplug
Incorrect carburetor settings
Incorrect setting of transmitter Exponential function.
Symptom
Poor r.p.m. drop
Cause
Throttle position open too far.
Too much closing of the needle-valve
and/or mixture control screw.
Incorrect carburetor installation
Corrective action
Replace glowplug.
Readjust low r.p.m. range with metering
needle and mixture control valve.
Check the transmitter setting.
Corrective action
Lower the throttle trim on the transmitter.
Open the needle-valve an/or mixture control
screw a little.
Install carburetor properly.
31
ENGINE EXPLODED VIEW
ENGINE PARTS LIST
32
10
C.M2.6x18
11
C.M3x18
12
No.
Code No.
1
23754740
1-1
23754720
1-2
1
1-1
1-2
2-1
2
18
3
4
33
5
7
9
6
8
7
15
14
13
C.M2.6x7
17
16
45515010
2
23754710
2-1
23754720
3
23754730
4
23764010
5
23753020
6
23906000
7
23817000
8
23755000
9
23882000
10
23715000
11
23981700
12
23731000
13
23751010
14
23730010
15
23752020
16
23764020
17
23757000
18
23763010
71641700
71802200
22826140
22884250
The specifications are subject to alteration for improvement without notice.
Water cooled plug cap
Nipple No.18
Sealing Gasket
Water Cooled Head Assembly
Nipple No.18
Inner Head
Head Gasket (2pcs.)
Cylinder & Piston Assembly
Piston Pin
Piston Pin Retainer (2pcs.)
Connecting Rod
Carburetor Complete (Type 21D)
Carburetor Sealing Gasket
Carburetor Retainer Assembly
Crankshaft Ball Bearing (Front)
Crankcase
Crankshaft Ball Bearing (Rear)
Crankshaft
Cover Gasket
Cover Plate
Screw Set
Glow Plug T-P7
Flywheel No.2K
Exhaust Seal Ring
Dust Cap Set (3mm,16mm,18mm)
Description
Type of screw
C...Cap Screw M...Oval Fillister-Head Screw
F...Flat Head Screw N...Round Head Screw S...Set Screw
21D CARBURETOR EXPLODED VIEW
C.M3X8
1-1
4
1
2
5
3-2
10
11
6
7
8
9-4
9
9-1
9-5
9-2 9-3
S.M3X3
3-1
12
3
Type of screw
C...Cap Screw M...Oval Fillister-Head Screw
F...Flat Head Screw N...Round Head Screw S...Set Screw
34
CARBURETOR PARTS LIST
No.
Code No.
1
1-1
2
3
3-1
3-2
4
5
6
7
8
9
9-1
9-2
9-3
9-4
9-5
10
11
12
27381400
22826131
23882200
23882600
27981850
23882630
45581820
23882100
22681953
27881330
27681340
23881900
22681980
24981837
26381501
27381940
26711305
23882210
29015019
23818190
Throttle Lever Assembly
Throttle Lever Retaining Screw (2pcs.)
Carburetor Rotor
Mixture Control Valve Assembly
"O" Ring Set (2pcs.)
"O" Ring (S) (2pcs.)
Rotor Guide Screw
Carburetor Body
Fuel Inlet (No.1)
Mixture Control Screw
Mixture Control Valve Stopper
Needle Valve Assembly
Needle Assembly
"O" Ring (2pcs.)
Set Screw
Needle Valve Holder Assembly
Ratchet Spring
Carburetor Spacer
Carburetor Rubber Gasket
Carburetor Sealing Washer
The specifications are subject to alteration for improvement without notice.
Description
35
O.S. GENUINE PARTS & ACCESSORIES
GLOWPLUG
Hot
P6
(71641600)
Cold
P8
(71641600)
LOCK WASHER
(10set)
(55500002)
M3
SUPER
JOINT TUBE 21
(72106300)
DUST CAP SET
3mm
(73300305)
16mm
(73301612)
18mm
(73301812)
(5pcs.)
(3pcs.)
(3pcs.)
CRANKSHAFT
CLAMP
(71530200)
1521
CAP SCREW SET
M2.6x7
M2.6x18
36
SUPER FILTER
(L)
(72403050)
(10pcs.)
(79871020)
(79871055)
NON-BUBBLE
WEIGHT
(71531000)
LONG SOCKET WRENCH
WITH PLUG GRIP
(71521000)
O.S. GENUINE PARTS & ACCESSORIES
REMOTE NEEDLE
(23882900)
1-6
1-5
1-4
1-1
1-3
1
1-7
1-8
1-2
2
2-1 2-2
No.
Code No.
1
23882900
1-1
23882940
1-2
26711305
1-3
23818176
1-4
23882950
1-5
23882960
1-6
22881300
1-7
28282300
1-8
26381501
2
22681980
2-1
24981837
2-2
26381501
The specifications are subject to alteration for improvement without notice.
37
Description
Remote Needle Assembly
Remote Needle Holder Assembly
Ratchet Spring
Universal Nipple No.9
Remote Needle Nut
Remote Needle Plate
Plug Screw
Needle Control Lever
Retaining Screw
Needle
"O" Ring
Set Screw
JAPAN JAPAN
THREE VIEW DRAWING
Dimensions (mm)
SPECIFICATIONS
Displacement
■
Bore
■
Stroke
■
■
Practical R.P.M.
■
Power output
■
Weight
3.46 cc (0.211 cu.in.
16.6mm (0.654 in.
16.0mm (0.630 in.
3,000-40,000 r.p.m.
2.5 ps / 33,000 r.p.m.
340g (12oz.)
24
31
30.8
45
44.3
33.5
21
37
45
30.8
44
69.8
55
)
)
)
1
UNF / -28
4
34.3
22 44
38.3
28.9
73.8
89.1
27.5
34
21
22 42.2
38
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Copyright 2005 by O.S.Engines Mfg. Co., Ltd. All rights reserved. Printed in Japan.
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6-15 3-Chome Imagawa Higashisumiyoshi-ku
Osaka 546-0003, Japan
TEL. (06) 6702-0225
FAX. (06) 6704-2722
URL : http://www.os-engines.co.jp
020500
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