O.S. Engines 21VZ-B User Manual

MAX-21VZ-B V-Spec

OWNER'S INSTRUCTION MANUAL

It is of
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

• Keep these instructions in a safe place so that

• It is suggested that any instructions supplied

vital importance, before attempting to

instruction manual, so as to familiarize yourself
with the controls and other features of the
engine.

you may readily refer to them whenever
necessary.

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 CONSTRUCTION---------------- 6

NOTES WHEN APPLYING AN ELECTRIC
STARTER

ABOUT THE ENGINE-------------------- 8

BEFORE STARTING-------------------9-11

BASIC

CARBURETOR CONTROLS---------------12

GLOWPLUG---------------------------13

INSTALLATION
ACCESSORIES------------------------ 14

INSTALLATION------------------------- 15

-----------------------------

ENGINE PARTS

------------------

OF THE STANDARD

ENGINE - - - - 2-5

7

11

STARTING THE ENGINE & RUNNING-IN---16-19
FINAL ADJUSTMENT------------------20-22

CARBURETOR CLEANLINESS-------------22

CARE AND MAINTENANCE ------------ 23-24

CHECKING THE ENGINE ----------------- 24

GUARANTEE-----------------------25

TROUBLE SHOOTING-----------------26-29

ENGINE EXPLODED VIEW & PARTS LIST
CARBURETOR EXPLODED VIEW &

PARTS LIST-------------------------32-33

O.S. GENUINE

THREE VIEW DRAWING------------------36

1

PARTS & ACCESSORIES

- - - - 34-35

- - - 30-31

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.

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

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
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 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.

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 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
is a little tapered. The piston and
cylinder are designed to achieve
a perfect running clearance
when they reach their running
temperatures.

Around TDC

Piston

Cylinder Liner

Crankshaft

A little tapered

When the engine is cold. When the engine is hot.

6

NOTES WHEN APPLYING
AN ELECTRIC STARTER

Do not over-prime. This could
cause 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 waste to
prevent pumped out fuel coming
into your eyes. NOTE

As delivered, the engine has its
carburetor lightly fit into its intake.
Secure it changing its angle
according to the car chassis.

7

ABOUT THE ENGINE

The MAX-21 VZ-B V-Spec is a high per­formance 3.5cc class power unit for one­eight-scale radio-controlled 'off-road' or

'buggy' cars. It has been expressly de­signed for racing competitions.
T-type plug (turbo plug) design improves
the power, fuel consumption and durabili-

ty.
The new 21 C carburetor is supplied with

8mm and 9mm dia. reducers to manage
different course conditions.

Standard accessories

Glow Plug P3 T-type head (Turbo head)
1piece

(Hot Type)

Cylinder-head gasket (0.1mm) 1 sheet

Exhaust Seal Ring 1 piece

Carburetor Reducer 8mm (Red) 1 piece
(w/ "0" Ring)

Dust Cap 03,016,018 every Ipiece

8

BEFORE STARTING

Tools, accessories, etc.The following items are
necessary for operating the engine.

Optional Extras

GLOW PLUG T-Type (Turbo Plug)

P3 is supplied with the engine. As
replacement, suggested O.S. plugs are
P3 and P6.

SUPER AIR CLEANER 203 ASSEMBLY

This is a heavy-duty wet type
air cleaner designed specifically
tor 3.5cc 'off-road' model car

engines.

T-2050 EXHAUST HEADER PIPE ASSEMBLY

This is designed to use with the T-2050
Tuned Silencer

T-2050 TUNED SILENCER ASSEMBLY

This is designed specifically for 3.5cc 'off-road'
model car engines.

T-2050 TUNED SILENCER COMPLETE SET

This is a set of T-2050 Tuned Silencer and T­2050 Exhaust Header Pipe Assembly.

TOOLS

HEX WRENCH

Necessary for engine installation.

1.5mm, 2mm, 2.5mm, 3mm opposite side

SCREWDRIVER

Necessary for carburetor adjustments.

No.1,No.2,etc

9

LONG SOCKET WRENCH WITH PLUG GRIP REMINDER!

Recommended for easy removal and
replacement of the angled and recessed
glowplug, the O.S.Long Socket Wrench
incorporates a special grip.

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
the reach of children.

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.

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.

FUEL FILTER

To fit in the fuel line between fuel
tank and carburetor to prevent
dust coming into the carburetor.

GLOWPLUG IGNITER

Commercialy available handy
glowplug heater in which the
glowplug battery and battery
leads are integrated.

10

of

STARTER BOX

For starting the engine.

7.2V BATTERIES FOR STARTER BOX

Batteries for starter box.
Select according to the
starter box used. Be sure to
full charge before using.

FUEL PUMP

For filling the fuel tank, a simple,
polyethylene "squeeze" bottle,

with a suitable spout, is required.

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.

BASIC ENGINE PARTS

Heatsink Head

Carburetor

Type 21 C

Exhaust

Cover Plate

Mounting Lugs

Crankcase

Crankshaft

11