O.S. engine MAX-25XZ Manuale utente

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.

Expressly for 1/8 off-road truck (Truggy)

racing competitions

2-5

19-23

27-29

24-26

30-33

34-35

10-12

CONTENTS

INSTALLATION OF THE CARBURETOR

ENGINE INSTALLATION

STARTING THE ENGINE &RUNNING-IN

("Breakinh-in")

FINAL ADJUSTMENT

CARE AND MAINTENANCE,

CHECKING THE ENGINE

TROUBLE SHOOTING

ENGINE EXPLODED VIEW & PARTS LIST

CARBURETOR EXPLODED VIEW &

PARTS LIST

O.S. GENUINE PARTS & ACCESSORIES

THREE VIEW DRAWING

36-37

SAFETY INSTRUCTIONS AND

WARNINGS ABOUT YOUR O.S. ENGINE

ENGINE CONSTRUCTION

NOTES WHEN APPLYING AN ELECTRIC

STARTER

NOTES ON OPERATION

ABOUT THE ENGINE

BEFORE STARTING

BASIC ENGINE PARTS

CARBURETOR CONTROLS

GLOWPLUG

INSTALLATION OF THE STANDARD

ACCESSORIES

38-39

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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

eyesormouth.Alwaysstore

it in a clearly marked con-

tainer 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 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.

••

•

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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

•

!

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.

•

Before starting the engine, always check

the tightness of all the screws and nuts

especially the mounting screws and

movable parts such as the throttle arm.

Missing retightening the loose screws

and nuts often causes the parts

breakage that is capable of harming you.

Piston

Cylinder Liner

Crankshaft

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

Slight taper

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

NOTES WHEN APPLYING

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 any pumped out fuel from

getting into your eyes.

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.

As delivered, the engine has the

carburetor lightly fit into its intake.

Secure it changing its angle according

to the car chassis.

NOTE

Please do not run on a public street, this

could cause serious accidents, personal

injuries and/or propetry damage.

Please do not run near pedestrians or

small children.

Please do not run in small or confined

areas.

Please do not run where loud noises can

disturb others, such as hospitals and

residential areas.

While Operating

NOTES ON OPERATION

Standard accessories

Glow Plug P3 T-type head (Turbo head)

1piece

Exhaust Seal Ring 1piece

Dust Cap 3, 16, 18 1piece each

The MAX-25XZ is a high performance .25

cu.in. class power unit for one-eight-scale

radio-controlled truck type (Truggy) cars.

It has been expressly designed for racing

competitions. It features a large size

outer head and T-type plug (turbo plug)

design.

The 21JN carburetor is supplied with

8mm reducers to manage different

course conditions.

(Hot Type)

ABOUT THE ENGINE

Tools, accessories, etc.The following items are

necessary for operating the engine.

T-2060 WN TUNED SILENCER ASSEMBLY

M2000 EXHAUST HEADER PIPE ASSEMBLY

T-2060SC WN TUNED SILENCER COMPLETE SET

SUPER AIR CLEANER 203 ASSEMBLY

BEFORE STARTING

Optional Extras

GLOW PLUG T-Type (Turbo Plug)

P3 is supplied with the engine. As

replacement, suggested O.S. plugs are

P3 and P4.

This is a heavy-duty wet type air cleaner

designed specifically for 3.5cc ‘off-road’ model

car engines.

This is designed to use with the T-2060

Tuned Silencer.

This is designed specifically for 3.5cc ‘off-road’

model car engines.

This is a set of T-2060SC Tuned Silencer and

M2000SC Exhaust Header Pipe Assembly.

T-2060SC WN TUNED SILENCER ASSEMBLY

M2000SC EXHAUST HEADER PIPE ASSEMBLY

This is designed to use with the T-2060SC

Tuned Silencer.

This is designed specifically for 3.5cc ‘off-road’

model car engines.

SUPER JOINT TUBE 21

28XZ HYPER FLYWHEEL SETS

They are designed to match the engine power

characteristics.

This is to use with joint tube connection type

silencer.

TOOLS

HEX SCREWDRIVER

SCREWDRIVER

Necessary for engine installation.

1.5mm, 2mm, 2.5mm

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.

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.

Items necessary for starting

!



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.

REMINDER!

FUEL FILTER

GLOWPLUG IGNITER

Commercialy available handy

glowplug heater in which the

glowplug battery and battery

leads are integrated.

To installed in the fuel line between

fuel tank and carburetor to prevent

foreign matter from entering the

carburetor.

FUEL PUMP

For filling the fuel tank, a simple,

polyethylene "squeeze" bottle,

with a suitable spout, is required.

STARTER BOX

For starting the engine.

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.

7.2V BATTERIES FOR STARTER BOX

Batteries for starter box.

Select according to the

starter box used. Be sure to

fully charge before using.

!

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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.

Outer Head

Crankcase

Mounting Lugs

Exhaust

Cover Plate

Carburetor

Type 21JN

Crankshaft

BASIC ENGINE PARTS

Crankshaft Bearing (Front)

The Needle-Valve(Adjusted at the factory):

The Mixture Control Valve:

Four adjustable controls are provided on

this carburetor.

For adjusting the mixture strength when the

throttle is fully open.

For changing the mixture strength at mid

speed and acceleration. (Do not rotate the

screw more chan one turn.)

The Throttle Stop Screw

(Adjusted at the factory):

For setting the minimum idle speed:

For adjusting the mixture strength at part-

throttle and idle speed, to obtain steady

idling and smooth acceleration to mid speed.

The Metering Needle:

NOTE: Readjustment may be necessary,

occasionally to allow for changes in fuel

formula, gear ratio or clutch engagement

point.

CARBURETOR CONTROLS 21JN

Metering Needle

Throttle Stop

Screw

Mixture Control Valve

Needle Valve

Thermo Insulator

Carburetor Reducer

Ball Link

Dust Cover

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.

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 P3 and P4.

Carefully install plug finger-tight, before

final tightening with the correct size plug

wrench.

Install the exhaust seal ring supplied.

Exhaust

Seal Ring

Glowplug

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.

Installing the glow plug. Insert P3 plug supplied

into heatsink-head carefully, making sure that

it is not cross-threaded before tightening firmly.

(All the O.S. T-Type plugs including the P3 are

not supplied with a washer.)

INSTALLATION OF THE STANDARD ACCESSORIES

INSTALLATION OF THE CARBURETOR

As delivered, the engine has its carburetor

lightly installed in the 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 nut

gently until it stops.

Tighten 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.

Note

Be careful not to damage the O rings when

removing the carburetor retainer from the

engine.

First, remove the retainer Retaining screw,

then pull out each part. Do not push the

part in or damage the O rings.

Retaining Screw

"O" Ring

Pull out.

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 them slightly with a needle-file so that

screws are in alignment with the mounting holes.

Chamfer inside edges of bearers.

Do not allow bottom

of crankcase to

touch chassis.

Note:

Be sure to use a collet supplied when use a

optional 28XZ Hyper Flywheel Set.

The engine bottom may interfere with chassis

of some models. In this case, file off the

chassis so that the engine may not interfere

with the chassis when it is installed.

NOTE

STARTING THE ENGINE & RUNNING-IN ('Breaking-in)

PRESSURIZED FUEL SYSTEM

!



Before starting the engine, always

check the tightness of all the screws

and nuts especially the mounting

screws 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.

Never run your vehicle without installing the air

cleaner. Dust and dirt that may otherwise be drawn

into the engine will rapidly shorten its life.

The somewhat violent changes of vehicle attitude

that occur in off-road running, combined with the

fact that, in buggy type cars, the fuel tank is often

located some distance from the carburetor, which

means that the fuel 'head' at the carburetor can vary

and upset running.Therefore,it is recommended that

a muffler pressurized fuel feed system be used.

Running- in is a procedure for an engine to come

close to actual running conditions (fuel, r.p.m.,

engine temperature, etc.).

Excessively rich running and prolonged low

speed running should be avoided. Prolonged low

speed running and low temperature running may

result in the oil in the fuel becoming gelled and

the piston/liner becoming stuck together.

RUNNING-IN ('Breaking-in)

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