O.S. engine MAX-15LD, Owner'S Instruction Manual

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.

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TOOLS, ACCESSORIES, etc.

The following items are necessary for operating the 
engine.

FUEL

Use only top quality methanol-based model engine 
fuel.For consistent performance and long engine life, 
it is advisable to use fuel containing AT LEAST 18% 
lubricant. This engine is designed to run on both low and 
high nitromethane content fuels,i.e. from mild mixtures 
containing a few percent of nitromethane, up to high-
speed racing fuels containing 40% nitromethane. 
Generally, power output is increased-up to a certain 
point-as the nitromethane content of the fuelis increased.

As a starting point, we recommend a fuel containing 10-
20% nitromethane, changing to a fuel containing more 
nitro only if necessary. When the nitro content of the fuel 
is increased or the brand of fuel is changed, it is advisable 
to initially run the engine with a richer needle-valve 
setting, so that the optimum setting for the new fuel may 
be rechecked as described in the RUNNING-IN 
paragraphs. When engines are run at very high speeds 
and on high-nitro fuels, glowplug elements do not last 
so long. 

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. 

Reminder!

GLOWPLUG BATTERY

The power source for heating the glowplug may be 
either  a large heavy-duty 1.5Volt dry cell, or  a 2-Volt 
rechargeable lead-acid cell with extended leads (or a 
resistance) to reduce the applied voltage to 

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