O.S. engine MAX-21VZ-R 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.
●
●
●

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.
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.

WARNINGS
Model engine fuel is poi-
sonous. 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
whichmightigniteit.Donot
smokeorallowanyoneelse
to smoke, near to it.
Never operate your engine in an en-
closed 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

This engine is intended for model cars.
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
more powerful highspeed engines)
may eventually impair your hearing
and such noise is also likely to cause
annoyance to others over a wide area.
The wearing of safety glasses is also
strongly recommended.
Take care that the glowplug clip or
battery leads do not come into contact
with rotating parts. Also check that the
linkage to the throttle arm is secure.
For their safety, keep all onlookers
(especially small children) well back
(at least 20 feet or 6 meters) when
preparing your model for running.
NOTES
•
•
•
•
•
•
4

NOTES
To stop the engine, fully retard the
throttle stick and trim lever on the
trans-mitter, or, in an emergency, cut
off the fuel supply by pinching the fuel
delivery line from the tank.
•
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.
•
5

BASIC ENGINE PARTS
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.
Heatsink Head
Carburetor
Type 20K
Crankshaft
Crankcase
Mounting Lugs
Exhaust
As delivered, the engine has its carburetor lightly
fit into its intake. Secure it changing its angle
according to the car chassis.
NOTE
Standard accessories
Glow Plug P7 Cylinder-head gasket (0.1mm)
Exhaust Seal Ring Dust Cap 3, 16, 18
The MAX-21VZ-R is high performance 3.5cc
class power unit for one-eighth-scale radio-
controlled 'Track racing' cars. It has been de-
signed to meet the exacting requirements of
the world's most expert drivers. An exhaustive
program of research, development and proto-
type testing has resulted in one of the most
powerful production model racing car engines
currently available.
NOTE
The engine is fitted with one each of 0.1mm and
0.2mm cylinder-head gasket when leaves the
factory. Another 0.1mm head gasket is supplied
with the engine. You may addit at initial running-
in, when a glow plug tends to burn out due to high
temperature and / or high humidity or when you
prefer fuel economy to power.
Cover Plate
6

ENGINE INSTALLATION
Make sure that the vehicle's engine mounting
surfaces are level and in the same plane. Poor
installation may cause distortion of the
crankcase, bearings, etc., resulting in erratic
running and loss of performance.
The recommended screws for securing the
engine are 3mm or 4-40 steel Allen hexagon
socket type.
If existing holes in the engine mount do not align
perfectly with engine mounting lugs, enlarge
themslightlywithaneedle-filesothatscrewsare
in alignment with the mounting holes.
Chassis
Chamfer inside edges of bearers.
INSTALLATION OF THE CARBURETOR
Asdelivered,theenginehasitscarburetorlightly
install 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.
1.
2. Rotate the
retainer nut
gently until
it stops.
Tighten a
further
120-180˚
Rotate the retainer
screw gently until it
stops, then tighten
a further 120-180˚.
Do not overtighten
the screw as this
will damage the
carburetor body.
1.
2. Install the exhaust seal ring supplied.
Insert carefully into heatsink head, making
sure that it is not cross-threaded before
tightening firmly.
Do not allow bottom
of crankcase to
touch chassis.
7

Since the compatibility of glowplug and fuel may have
a marked effect on performance and reliability, it may
be worthwhile to choose the R/C type plug found
most suitable after tests. Recommended O.S. plugs
are P7. Carefully install plug finger-tight, before final
tightening with the correct size plug wrench.
GLOWPLUG
The role of the glowplug
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.
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.
•
•
•
Apart from when actually burned out, a plug may
need to be replaced because it no longer delivers its
best performance, such as when:
When to replace the glowplug
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.
•
•
•
•
•
8

TOOLS, ACCESSORIES, etc.
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.
The following items are necessary for operating the
engine.
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.
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.
Please note that with high-nitro fuels, although power
may be increased for competition purposes, glowplug
elements do not last so long and engine life will be
shortened.
BATTERY INTEGRATED GLOWPLUG HEATER
Commercialy available handy
glowplug heater in which the
glowplug battery and battery
leads are integrated.
FUEL PUMP
For filling the fuel tank, a simple,
polyethylene "squeeze" bottle,
with a suitable spout, is required.
STARTER BOX
For starting the engine.
9

LONG SOCKET WRENCH
Recommendedfor easyremoval
and replacement of the angled
and recessed glowplug, the
O.S.Long Socket Wrench
incorporates a special grip.
SILICONE FUEL LINE
Heatproof silicone tubing of
approx. 5mm o.d. and 2mm i.d.
is required for the connection
between the fuel tank and
engine.
CARBURETOR CONTROLS
The Needle-Valve:
•
The Mixture Control Screw:
•
The Throttle Stop Screw:
For setting the minimum idling speed:
•
Four adjustable controls are provided on this
carburettor.
For adjusting the mixture strength when the throttle
is fully open.
For adjusting the mixture strength at part-throttle
and idling speeds, to obtain steady idling and
smooth acceleration to mid speeds.
Needle Valve
Mixture Control Valve
Assembly Screw
Throttle Stop Screw
NOTE: Readjustment may be necessary,
occasionally to allow for changes in fuel formula
gear ratio or clutch engagement point.
The Metering Needle:
•
Metering Needle
For changing the feeling at mid speads and
acceleration. (Do not rotate the screw more chan
one turn.)
10

•
•
•
0.3 ~ 0.5mm
Use the same fuel as is to be employed for all initial
running and containing NOT LESS THAN 18%
lubricant.
STARTING THE ENGINE & RUNNING-IN ('Breaking-in')
Open
Close Needle Valve
The following procedure is suitable for these engines
when the O.S. T-2040 tuned silencer and a fuel
containing up to 30% nitromethane are used.
For long life and high performance, every engine
needs to be 'run-in' or 'broken-in'. With care, running-
in of the MAX-21VZ-R can be carried out with it
installed in the vehicle. Be sure to install the air-
cleaner on the carburetor and to use a muffler-
pressurized fuel system.
Temporarily remove the glowplug to check that it
glows bright red when energized.
Open the Needle-Valve 3 turns from the fully closed
position.
Switch on the transmitter and receiver and set the
throttle very slightly opened from the idling position
(see sketch, top right).
DO NOT energize glowplug, but apply electric
starter to draw fuel to carburetor.
Now connect glowplug battery lead to heat the plug
filament and start the engine.
•
•
•
It is vitally important to set the
throttle at the correct position
before starting the engine. If
the engine is allowed to run
with the throttle too far open
under''noload''conditions(i.e.
with the driving wheels not in
contact with the ground) it will
rapidly over-heat and may be
seriously damaged.
Attention:
11

When the engine starts, first allow it to operate in
short runs at the very rich starting settings, with the
glowplug battery still connected and the driving
wheels clear of the ground.
The rich mixture will, under these conditions,
provide adequate lubrication and cooling, indicated
by profuse smoke from the exhaust.
Next, disconnect the glowplug battery and try
running the car on the track. 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 Needle-Valve 30˚ and try again.
◆To stop the engine, close the throttle to idling
speed, then shut it off completely with the trim lever
on the transmitter. To cut off the fuel supply, pinch
the fuel delivery line to the carburetor.
Run the car on the track until one tank of fuel has
been consumed, then close the Needle-Valve 30˚
and run the car 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.
30°
30°
30°
Needle
The position of the needle-valve
when starting the engine.
Close the needle-valve approx.
30˚ after running the vehicle for
one full tank of fuel.
Repeat this procedure several times.
•
•
•
◆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.
12

IF THE ENGINE FAILS TO START
Check the following:
Glowplug battery discharged or glowplug defunct.
Fuel not reaching carburetor.
◆
◆
◆Engine flooded. Do not over-
prime. (This could also cause
hydraulic lock and damage
the engine on application of
the electric starter.)
Remove glowplug, close
needle-valve and apply star-
ter to pump out surplus fuel.
Run the vehicle (with throttle fully open) over the
longest available straight course, in order to observe
the model's speed. Next return the car to the starting
point,closetheNeedle-Valve30˚andrepeattherun,
taking note of the improvement in performance.
Continue with further runs, gradually reducing the
Needle-Valve 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 vehicle and reopen the Needle-Valve 45~90˚.
◆
FINAL ADJUSTMENT
◆Having established the optimum Needle-Valve
setting, check the Mixture Control Valve setting as
follows.
13

Warning!
Mixture adjustments (whether via the Metering
Needle, 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 revolutions increase 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 the needle-valve and
metering needle 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.
◆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 vehicle does not
accelerate smoothly and rapidly, it is probable that
the idling mixture is too rich.
In this case, turn the Metering Needle clockwise
45~90˚. If, on the other hand, the engine tends to
speed up momentarily and then cut out abruptly
when the throttle is opened, the idling mixture is
too lean. Correct this by turning the Metering
Needle counter-clockwise 45-90˚.
NOTE:
◆
Metering Needle adjustment should be made in
steps of not more than 45~90˚, carefully checking
the effect,on throttle response, of each small
adjustment.
Carry out adjustments patiently, under actual
running conditions, until the engine responds
quickly and positively to the throttle control.
14

Mixture Control Valve
Carburetor Body
First rotate the Mixture Control
Valve until its slotted head is
flush with the carburetor body.
This is the standard position.
CARBURETOR CLEANLINESS
The correct functioning of the carburetor depends on
its small fuel orifices remaining clear.
(See Care and Maintenance section on Page17.)
■
Slide Valve
Carburetor Body
Metering Needle
REALIGNMENT OF METERING NEEDLE AND
MIXTURE CONTROL VALVE
First rotate the Metering
Needle until its slotted head is
flush with the carburetor body.
This is the standard position.
In the course of making carburetor adjustments, it is
just possible that the Metering Needle and the Mixture
Control Valve may be inadvertently screwed in or out
too far and thereby moved beyond its effective
adjustment range.
Its basic position can be found by rotating the
Metering Needle and Mixture Control Valve until its
slotted head is flush with ball link the carburetor body.
Ball Link
15

Warning!
Do not attempt to turn the engine with the starter
if the engine is over-primed (flooded) with fuel.
To do so is likely to seriously damage the engine.
CARE AND MAINTENANCE
1.
2.
3.
The minute particles of foreign matter, that are
present in any fuel may, by accumulating and
partially obstructing fuel flow, cause engine
performance to become erratic and unreliable.
O.S. 'Super-Filters' (large and small) are available,
as optional extras, to deal with this problem.
One of these filters installed to the outlet tube inside
your refueling container, will prevent the entry of
foreign material into the fuel tank. It is also
recommended that a good in-line filter be installed
between the tank and carburetor.
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 glow-plug and try to restart
the engine, to burn off any fuel that may remain
BEFORE STARTING THE ENGINE
1.
2.
Before starting the engine for the first run of the day,
remove the glowplug and check the engine by
rotating the flywheel by hand. It should rotate
smoothly. Now turn the engine with an electric
starter until fuel is drawn into the carburetor. At first,
rotation may feel 'sticky' due to oily residue
remaining within the engine. The engine should
rotate freely after fresh fuel has been drawn into the
working parts.
Check the glowplug. If the plug element is distorted,
off center, or has a white appearance, engine
performance may be below par. With racing type
engines, glowplugs have to be regarded as
expendable items. Therefore, replace the plug if
necessary.
3.Reinstall the glowplug and start the engine.
4.When re-starting the engine, turn the flywheel by
hand, as before (but without removing the glow-
plug) to make sure that there is nothing unusual,
before energising the glowplug and applying the
starter.
16

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, 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.
4. Then, inject some after-run oil into the engine, and
rotate the engine with an electric starter for 4 to 5
seconds to distribute the oil to all the working
parts.
inside the engine. Repeat this procedure until the
engine fails to fire. Do this while the engine is still
warm.
Note:
5.
Do not inject after-run oil into the carburetor as
this may cause the O-rings inside the carburetor
to deteriorate. These procedures will reduce the
risks of starting difficulties or corrosion after a
period of storage.
Finally, 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.
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.
17

ENGINE EXPLODED VIEW
Type of screw C…Cap Screw M…Oval Fillister-Head Screw
F…Flat Head Screw N…Round Head Screw S…Set Screw
✽
4
3
2
C.M2.6X7
q
-
0
9
8
6
5
4
1
1-1
1-2
7
=
w
e
r
C.M3X16
C.M2.6X18
18

ENGINE PARTS LIST
The specifications are subject to alteration for improvement without notice.
Screw Set
Gasket Set
Crankshaft
Crankshaft Ball Bearing (Rear)
Exhaust Seal Ring
Crankcase
Crankshaft Ball Bearing (Front)
Carburetor Retainer Assembly
Carburetor Complete (Type 20K)
Connecting Rod
Piston Pin Retainer(2pcs.)
Piston Pin
Cylinder & Piston Assembly
Heatsink Head Assembly
Description
Code No.
Cover Plate
e
w
q
=
-
0
9
8
7
6
5
4
3
2
1
23757000
22826140
71641700
23763000
23764000
23752000
23730010
23751000
23731000
23715000
23781000
23755000
23817000
23906000
23753000
23754600
No.
1-1
1-2
r
23754620
23754610
23818190
23981700
Outer Head
Inner Head
Carburetor Sealing Gasket
Carburetor Sealing Washer
Glow Plug P7
19

The specifications are subject to alteration for improvement
without notice.
Type of screw
C…Cap Screw M…Oval Fillister-Head Screw
F…Flat Head Screw N…Round Head Screw S…Set Screw
✽
CARBURETOR EXPLODED VIEW & PARTS LIST
5
4
3
2
1
9
7
6
8
1-1
1-2
2-1 2-2
S.M3X3
2-3
2-4
6-1
Carburetor Rubber Gasket
Ball Link No.3
Dust Cover
Metering Needle Assembly
Slide Valve
Carburetor Body
Fuel Inlet (No.9)
"O" Ring
Needle Valve Assembly
Throttle Stop Screw
"O" Ring(S) (2pcs.)
"O" Ring(L) (2pcs.)
Mixture Control Valve Assembly
Description
Code No.
Needle
Needle Holder Assembly
9
8
7
6
5
4
2-2
2-1
3
2
1-2
1-1
1
29015019
23781400
22884220
27881820
23781610
23781200
23781100
23818176
46066319
23618190
23818500
22781800
46066319
23781600
2-3
2-4
23618197
23618194
No.
6-1
"O" Ring
20