O.S. engine MAX-25AX & MAX-35AX User Manual

It is of vital importance, before attempting to operate
your engine, to read the general 'SAFETY
INSTRUCTIONS AND WARNINGS' section on
pages 2-6 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 aircraft, radio control equipment, etc., are
accessible for checking at the same time.
Two-Stroke Engine For Airplanes
1
2-6
7-8
9
10
20-21
22
27-30
33
15-17
SAFETY INSTRUCTIONS AND WARNINGS
ABOUT YOUR O.S. ENGINE
ENGINE CONSTRUCTION,
NOTES WHEN APPLYING AN ELECTTRIC STARTER
ABOUT THE ENGINE
BASIC ENGINE PARTS
BEFORE STARTING
INSTALLATION
INSTALLATION OF THE STANDARD ACCESSORIES
FUEL TANK LOCATION
MIXTURE CONTROLS
GLOWPLUG
STARTING
CONTENTS
RUNNING -IN, IDLING ADJUSTMENT CHART
MIXTURE CONTROL VALVE ADJUSTMENT
REALIGNMENT OF MIXTURE CONTROL VALVE,
SUBSEQUENT STARTINGPROCEDURE
SUBSEQUENT READJUSTMENT,
CARBURETOR CLEANLINESS
TROUBLE SHOOTING WHEN THE
ENGINE FAILS TO START
CARE AND MAINTENANCE
ENGINE/ CARBURETOR EXPLODED
VIEWS & PARTS LIST
O.S. GENUINE PARTS & ACCESSORIES
THREE VIEW DRAWING
MEMO
31
32
34-35
36-37
38-45
11-14
18-19
23
46-47
48-49
24-26
50

O.S. engine MAX-25AX & MAX-35AX Specifications

General

Brand	O.S. engine
Model	MAX-25AX & MAX-35AX
Category	Engine
Language	English

Summary

Safety Instructions and Warnings

Warnings

Covers events that might involve serious or fatal injury due to misuse.

Notes

Covers less obvious dangers that may cause damage or injury under certain circumstances.

Engine Construction and Starter Notes

Engine Construction

Explains the piston and cylinder design for optimal clearance at operating temperature.

Notes When Applying an Electric Starter

Provides guidance on avoiding hydraulic lock and damage when using an electric starter.

About the Engine

Engine Overview

Introduces the MAX-25AX & MAX-35AX engines and their features.

Standard Accessories

Lists the standard accessories included with the MAX-25AX/35AX engines.

Basic Engine Parts

Engine Component Identification

Identifies and labels the key parts of the engine with a diagram.

Before Starting

Propeller Selection and Safety

Discusses propeller choice based on aircraft and flying type, emphasizing balance and safety.

Spinner Installation

Recommends using a precision-made spinner for centering the electric starter sleeve.

Installation

Engine Mounting

Details correct and incorrect methods for mounting the engine to ensure stability.

Fastening Mounting Screws

Explains how to fasten mounting screws for both hardwood and radial motor mounts.

Throttle Linkage Connection

Guides on connecting the throttle linkage to the servo for proper operation.

Installation of Standard Accessories

Installing the Glowplug

Provides instructions on correctly installing the glowplug with a washer.

Needle-Valve Extension Installation

Explains how to install the needle-valve extension for external adjustment.

Installing the Silencer

Details how to secure the silencer and adjust its outlet position.

Fuel Tank Location

Fuel Tank Capacity and Placement

Suggests fuel tank capacities and placement for optimal fuel system performance.

Fuel Line and Pickup

Advises on selecting fuel tubing and positioning the pickup weight.

Mixture Controls

Carburetor Mixture Controls

Explains the roles of the Needle Valve and Mixture Control Valve in fuel metering.

Glowplug

Glowplug Usage and Selection

Discusses glowplug types, installation, and factors affecting plug life.

Glowplug Replacement Criteria

Lists signs indicating when a glowplug needs replacement for optimal performance.

Starting Procedure

Electric Starter Operation

Emphasizes using an electric starter and checking all fasteners before starting.

Step-by-Step Starting Guide

Provides a detailed, numbered procedure for starting the engine using an electric starter.

Engine Stopping Method

Describes the correct procedure for stopping the engine using the transmitter controls.

Running-In Procedure

Importance of Running-In

Explains why running-in is vital for engine parts to mate correctly at operating temperature.

Short Running-In Process

Outlines a simple, short running-in procedure for O.S. engines installed in models.

Subsequent Flights and Adjustments

Guides on adjusting the needle-valve for power during subsequent flights after break-in.

Idling Adjustment Chart

Idling Adjustment Procedure

Presents a chart detailing the steps for adjusting the engine's idle speed and mixture.

Mixture Control Valve Adjustment

Adjusting Idle Mixture

Explains how to adjust the Mixture Control Screw for optimal idle response.

Realigning Mixture Control Valve

Setting Standard Mixture Control Position

Describes how to find the standard position for the Mixture Control Valve.

Subsequent Readjustment

Fine-Tuning Mixture Settings

Advises on minor readjustments of the Needle-Valve due to varying conditions or parts.

Carburetor Cleanliness

Maintaining Carburetor Cleanliness

Stresses the importance of keeping carburetor orifices clear of foreign matter.

Trouble Shooting Engine Start

Key Starting Points

Lists four key conditions required for good engine starting.

Engine Fails to Fire Troubleshooting

Provides corrective actions for symptoms like sluggish rotation or failure to fire.

Engine Runs Intermittently Troubleshooting

Offers solutions for engines that fire intermittently or stop after starting.

Care and Maintenance

General Maintenance Precautions

Advises on preventing dust, keeping fuel clean, and installing fuel filters.

Engine Storage and Cleaning

Details procedures for long-term engine storage and cleaning to prevent corrosion.

25AX Engine Exploded View and Parts List

25AX Engine Parts List

Lists and identifies all parts of the 25AX engine with code numbers.

21L Carburetor Exploded View and Parts List

21L Carburetor Parts List

Lists and identifies all parts of the 21L carburetor with code numbers.

35AX Engine Exploded View and Parts List

35AX Engine Parts List

Lists and identifies all parts of the 35AX engine with code numbers.

21K Carburetor Exploded View and Parts List

21K Carburetor Parts List

Lists and identifies all parts of the 21K carburetor with code numbers.

O.S. Genuine Parts and Accessories

O.S. Genuine Parts and Accessories Listing

Lists various O.S. genuine parts and accessories available for purchase.

Three View Drawings

25AX Three View Drawing

Provides detailed dimensions and views of the 25AX engine.

35AX Three View Drawing

Provides detailed dimensions and views of the 35AX engine.

Memo

User Notes Section

A blank section for users to record personal notes and observations.