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Glow Plug Recommendation
Glow plugs can also make a big difference on the performance of your
engine. For the XL 1.20RFS we recommend using a glow intended spe-
cifically for four cycle engines. Do not use glow plugs intended for two
cycle engines. This can lead to erratic engine runs and eventual engine
wear and failure.
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Fuel Recommendation
Fuel can make a big difference in the way your engine performs. We rec-
ommend using two types of fuel with the XL 1.20RFS. For the break-in
period you must use a fuel containing no more than 10% Nitromethane and
no less than 20% Castor Oil lubricant. Use of fuel containing more than
the recommended percentage of Nitro Methane or any synthetic lubricants
will cause the engine to run too hot and result in excessive wear and engine
failure in a very short period of time. Once the engine has been adequately
broken in (about 1 gallon of the recommended break-in fuel), a fuel con-
taining up to, but no more than 15% Nitro Methane and no less than 16%
Castor Oil and synthetic lubricant blended fuel can be used.
Note: We do not recommend using fuels that contain only synthetic
lubricants. Synthetic lubricants have a much lower flash point than Cas-
tor Oil lubricants. Flash point is the point at which the lubricant begins to
actually burn and loses it’s lubricating qualities. Using fuels containing a
blend of Castor Oil and synthetic lubricants results in an engine that runs
cooler and lasts longer. One lean run using a fuel containing only syn-
thetic lubricants can cause engine failure. Using fuels with a Castor Oil
and synthetic blend of lubricants greatly reduces this chance.
STARTING PROCEDURE
The XL 1.20RFS can be started using a heavy duty electric starter or it can
be started by hand. For safety and ease of starting, especially when the
engine is new, we recommend using an electric starter. The following two
procedures should be done with the power to the glow plug off.
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Starting with an Electric Starter
When using an electric starter it is not necessary to prime the engine. The
starter turns the engine over fast enough that the engine draws fuel on it’s
own. Priming the engine prior to using an electric starter can cause the
engine to “hydro-lock” or flood. This is a result of too much fuel in the
engine before it actually fires. Turning the engine over with an electric
starter while the engine is flooded can cause extreme damage to the engine
and/or cause your propeller assembly to come loose. Turn the propeller
through the compression stroke one time by hand to check for a hydro-
locked state before applying the starter.
HIGH & LOW SPEED NEEDLE VALVES
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High Speed Needle Valve
The high speed needle valve is used to meter the air/fuel mixture at full
throttle. Turn the needle clockwise to lean the mixture or turn the needle
counterclockwise to richen the mixture. When you start the engine for the
very first time the needle valve should be turned in completely, then backed
out 2-1/2 turns. When you start the engine after that, leave the needle
valve in the same position it was in when you shut down the engine.
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Low Speed Needle Valve
The low speed needle valve regulates the air/fuel mixture at idle and dur-
ing transition from idle to full throttle. Turn the idle mixture screw clock-
wise to lean the mixture. Turn it counterclockwise to richen the mixture.
The idle mixture screw is preset from the factory, but minor adjustments
may need to be made. To reset the mixture screw to the factory setting
open the carburetor barrel completely. While holding the barrel open, turn
the mixture screw out until it stops. From this point, turn the mixture
screw in 6 complete turns. This is the factory setting.
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Starting by Hand
When starting the engine by hand always use a chicken stick. Never just use
your hand or serious injury could result. To make the engine easier to start
by hand it should be primed. This is done by opening the carburetor com-
pletely and choking the engine using the hand operated choke. With the
carburetor choked, “pull” the propeller through the compression stroke 2 - 3
times. This will draw fuel into the engine. Release the choke and pull the
propeller through the compression stroke once to check for a hydro-locked
condition.
BREAK-IN PROCEDURE
Note: The XL 1.20RFS engine is a ringed engine. A ringed engine is
designed differently than a typical ABC designed engine that you might be
more familiar with, therefore you will not feel much hesitation as the pis-
ton moves through the top of the stroke. A ringed engine does not have any
taper in the sleeve. Ring tension is what seals the combustion chamber.
When the engine is brand new, it will not feel like it has much compression.
This is because the ring has not yet been seated with the sleeve. After the
engine has been broken-in, compression will increase. The break-in pro-
cedure will guide you through the steps necessary to properly break-in
your new XL 1.20 ringed engine. Please follow the steps closely.
The break-in process allows the engine parts to perfectly fit to each
other and properly protect each part from premature wear. The engine
should be broken in using a fuel that contains no more than 10% Nitro
Methane and no less than 20% Castor Oil lubricant. Synthetic lubricant
fuels should not be used during the break-in procedure. For the break-in
procedure we recommend mounting the engine into the airplane it will be
used in. This way the muffler, fuel tank and throttle linkage can all be
tested in combination with the engine. If your airplane uses a cowling, it
should be removed during the break-in procedure.
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1)
Turn the high speed needle valve out 2-1/2 turns from the fully
closed position.
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2)
If you are using an electric starter to start the engine, follow the
procedure in the previous section. If you are starting the engine by hand,
follow that procedure in the previous section.
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3)
Open the throttle barrel to approximately 1/4 throttle. Connect
the power to the glow plug. Start the engine using an electric starter or by
hand. If starting by hand you will need to vigorously flip the propeller
through the compression stroke several times before the engine will start.
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4)
Once the engine starts open the throttle barrel to about 1/2 throttle.
You may need to lean the high speed needle valve in about 1/4 turn to keep
the engine running at half throttle.
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5)
After the engine has been running about 1 minute, remove the
power from the glow plug. Advance the throttle barrel to full throttle.
Adjust the high speed needle valve so that the engine is running very rich.
You should notice excessive white smoke coming from the exhaust. Let
the engine run for approximately 5 minutes then stop the engine.
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6)
Let the engine cool for approximately 10 minutes then restart it.
Set the high speed needle valve mixture to a slightly leaner setting, about
1/4 turn more in. Let the engine run for about 5 minutes at this setting then
stop the engine and let it cool for approximately 10 minutes.
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7)
Repeat the procedure in step # 6, while leaning the needle valve
slightly more each time. In all, you should run the engine about a total of
30 minutes of actual running time. After 30 minutes of run time the engine
is ready for flight. Fly the airplane with the engine set as rich as possible,
but with adequate power to fly the airplane. After each flight, lean the
mixture slightly. Continue to do this for about 10 flights. At this point the
engine should hold a good setting on the high speed needle valve and you
can begin to fine tune the needle valve settings to increase performance.
