Magnum XL .25ARNV, XL .32ARNV, XL .28ARNV, XL .36ARNV Operating Instructions Manual
(XL .36A
RNV
Shown)
INTRODUCTION
The Magnum XL .25ARNV thru .36ARNV engines are single cylinder, two
cycle engines incorporating ABC piston and sleeve technology for long
life and easy break-in. A dual needle carburetor for precise adjustments is
standard on all four engines. All four engines incorporate a cast aluminum
rear needle valve assembly for safety . The engine was designed by expert
engineers and built by master craftsmen using only the highest quality materials and CNC machinery. These qualities provide the long life and dependability you have come to expect from an engine of this caliber.
BECOMING FAMILIAR WITH THE MAGNUM
XL .25ARNV thru .36ARNV ENGINES
Before attempting to operate your new engine, please read through this
instruction sheet in it’s entirety. This will help you familiarize yourself
with the features and operation of your new engine. Use the photos below
to identify the major component parts of your new engine.
Muffler Thru Bolt
Carburetor
Throttle Arm
Prop Washer
Prop Nut
Crankshaft
Thrust Washer
Rotor
Bolt
Throttle
Arm
Idle Mixture
Screw (inside
throttle arm)
Pressure Nipple
Muffler
(XL .36A
Nipple
RNV
Carburetor Retaining Bolt
Rotor
Bolt
Shown)
Idle
Mixture
Screw
Throttle
Arm
Fuel
Exhaust Cone
Cylinder Head
Needle Valve
Detent Spring
Needle Valve
Mount
Fuel Nipple
Crankcase
Idle Stop
Screw
Fuel
Nipple
(XL .28A
RNV
Shown)
OPERATING INSTRUCTIONS
XL .25ARNV - .28ARNV and
XL .32ARNV - .36ARNV
SPECIFICATIONS
XL .25 XL .28 XL .32 XL .36
Displacement (cc)
Bore (mm)
Stroke (mm)
Practical R.P.M.
Weight (w/Muffler)
Crankshaft Thread
4.05 4.57 5.26
17.42
18.5
19.5 20.5
8.5 8.5 8.8 8.8
2,000 - 16,000 2,000 - 16,000
11.2
10.8 12.3 12
2,000 - 16,000
1/4 - 28 1/4 - 28 1/4 - 28 1/4 - 28
WARNING!
Magnum model engines will consistently give you dependable performance
and reliability and will be a source of satisfaction and pleasure if you follow these instructions as to the engine’s proper and safe use. You alone are
responsible for the safe operation of your engine, so act sensibly and with
care at all times. This Magnum model engine is not a toy. It is a precision
built machine whose power is capable of causing serious injury to yourself
and others if abused, misused or if you fail to observe proper safety precautions while using it. Please read the safety warnings below carefully.
N Keep spectators, especially small children, at least 20 feet away from
the engine while it is running.
N Mount the engine securely in the airplane or on a suitable engine test
stand to run the engine. Follow the mounting instructions in your kits’ instruction manual or on the plans for individual mounting recommendations.
Do not clamp the engine in a vise to test run it.
N Use the recommended size propeller and follow the proper procedure
for mounting the propeller. Use the correct size wrench to tighten the
propeller nuts. Do not use pliers.
N Inspect the spinner, propeller and propeller nut on a regular basis,
looking for any signs of nicks, cracks or loosening.
N To stop the engine, adjust the throttle linkage to completely close the
throttle barrel and therefore cut off the air supply. You can also pinch the
fuel line to stop the engine, but only if it is safely accessible. Do not throw
anything into the spinning propeller or attempt to use your hands to stop
the engine.
N Stand behind the engine while it is running to make any adjustments
to the mixture controls. Do not reach over or around the propeller. Do not
lean towards the engine. Do not wear loose clothing or allow anything to
be drawn into the spinning propeller while the engine is running.
N If you need to carry your model while the engine is running, be conscious of the spinning propeller. Keep the airplane pointed away from you
and others at all times while the engine is running.
N Do not use tight fitting cowls or oversized spinners as these can impede airflow over the engine and result in overheating and possible severe
damage to the engine.
INSTALLATION
q Engine Orientation
The Magnum XL .25ARNV - .36ARNV engines can be orientated in any posi-
tion on the firewall. Keep in mind that when the engine is mounted inverted,
carburetor adjustments will need to made differently and the fuel tank may
need to be lowered. (See tank size and orientation to carburetor on next page).
5.81
2,000 - 16,000
q Engine Bolts and Firewall Requirements
The engine should be mounted to a glass filled nylon mount or an integrated hardwood beam mount. Use only high quality steel cap screws and
related hardware to mount the engine to the motor mount. The firewall in
the airplane should be aircraft grade 5-ply plywood and be no less than
1/4” thick. The firewall should also be reinforced to meet the torque and
weight of the engine.
q Muffler Installation
The muffler is mounted to the engine using the two socket cap screws, two
split washers and one of the two gaskets provided. The second gasket
Exhaust
Cone
should be kept as a spare. Tighten
both screws securely to prevent the
muffler from loosening during
flight. The exhaust cone on the rear
Thru Bolt
half of the muffler is adjustable to
better match the installation of your
particular application. T o adjust the
Retaining Nut
cone, loosen the retaining nut us-
ing a small wrench. Rotate the cone
to the desired angle then tighten the retaining nut completely while holding the thru bolt in place, from the front of the muffler, using a flat blade
screwdriver. It is important to tighten the retaining nut completely to prevent the cone from rotating during flight.
q Tank Size and Orientation to Carburetor
Ideally the stopper in the fuel tank should be even with the high speed
needle valve or just slightly below the high speed needle valve. Most
models will only allow the fuel tank to be mounted higher than the ideal
location. A fuel tank that is positioned higher than the ideal location usually doesn’t pose any problem except when it is mounted excessively higher
and/or used in conjunction with an inverted mounted engine or during extreme aerobatic flight. If mounting your engine inverted it is advised to
lower the fuel tank so the stopper is slightly below the high speed needle
valve. Doing this will prevent fuel from siphoning into the engine and
flooding it when the fuel tank is full. If you cannot lower the fuel tank far
enough, we suggest lowering it as far as can be allowed in your particular
application.
The size of the fuel tank used for the .25 or .28 should be 6oz. - 8oz.
depending on the model and the length of flights desired. Use of an 8oz.
tank will provide about 15 minutes of run time at full throttle. Use of a fuel
tank any larger than 8oz. can lead to excessive leaning of the engine mixture during flight and is not recommended.
The Size of the tank used for the .32 - .36 should be 8oz. - 10oz. Use
of a 10oz. tank will provide about 20 minutes of run time at full throttle.
Use of a tank any larger than 10oz. can lead to excessive leaning of the
engine mixture during flight and is not recommended.
q Carburetor Installation
The carburetor is held in place using two machine screws. Slide the base
of the carburetor into the crankcase,
being careful to keep the carbure-
Machine
Screw
tor perpendicular to the front of the
engine. With your thumb, push
down on the carburetor firmly so
the base of the carburetor sets completely into the crankcase and the
carburetor o-ring seals the gap be-
tween the crankcase and carburetor. While holding the carburetor in place, thread one machine screw into
each side of the carburetor. Use a screwdriver to carefully tighten both
screws securely. There is no need to overtighten the screws.
Note: Do not overtighten the retaining screws. The screws only
need to be tightened enough to keep the carburetor from moving in the
crankcase. Overtightening the screws can cause severe damage to the
base of the carburetor.
q Rear Needle Valve Installation
The rear needle valve assembly is held in place using the two socket cap
screws and two split washers pro-
Fuel
Line
vided with the assembly. To mount
the assembly, remove the two upper backplate screws, set the assembly in place, then install the two
screws and split washers provided
Mounting
Bracket
Socket
Screws
with the assembly. Tighten the
Cap
screws completely. Install the pro-
vided length of silicon fuel line
between the needle valve assembly and the carburetor. The fuel pickup
line from your fuel tank will connect to the larger brass nipple on the needle
valve assembly.
q Needle Valve Extension
If an extension is required to adjust the high speed needle valve, use a
1.5mm diameter wire of the necessary length. Loosen the set screw in
the side of the needle valve, insert the wire into the end of the needle
valve and tighten the set screw firmly. If the extension is more than 3”
long we recommend supporting the outer end of the extension to prevent
excessive vibration.
q Idle Stop Screw and Rotor Bolt
The rotor bolt holds the throttle barrel into the carburetor body on all four
of these engines. These bolts typically do not require any adjustment. On
the .25ARNV and the .28ARNV, the idle stop screw adjusts the closure of
the throttle barrel. We recommend that the throttle barrel be allowed to
close completely so the engine can be shut off using your radio transmitter. T urning the screw clockwise will cause the barrel to stay open more.
Turning the screw counterclockwise will allow the barrel to close more.
Do not turn the screw any further out than necessary to allow the throttle
barrel to fully close. The .32ARNV and .36ARNV does not utilize an idle
stop screw. Barrel closure is controlled completely by the transmitter.
q Propeller Installation
Note: Before installing any propeller it must be properly balanced.
Running an engine using an improperly balanced propeller can lead to excessive vibration, which can cause excessive stress and wear on both the
engine and the airframe. Balance the propeller using the recommended
method of the propeller manufacturer. Several products are available to
properly balance propellers. Ask your local retailer for more information
about these items.
Using a 1/4” drill bit or a prop
reamer, drill out the hole in the pro-
Prop
Washer
peller hub to fit the crankshaft. The
crankshaft is 1/4” in diameter.
Slide the propeller onto the crank-
Thrust
Washer
Prop
Nut
shaft, up against the thrust washer.
Slide the propeller washer up
against the propeller. Thread the
prop nut onto the crankshaft. Completely tighten the prop nut to secure the propeller in place. When tightening the prop nut, use the proper size open end wrench. Do not use pliers.
Note: If you are installing a spinner onto your engine the cone of
the spinner must not rub against the propeller. If the spinner cone rubs
against the propeller this could lead to propeller damage and eventual
propeller failure.
PROPELLER, FUEL & GLOW PLUG
q Propeller Recommendation
The diameter and pitch of the propeller needed for the XL .25ARNV thru
.36ARNV will vary greatly depending on the application the engine is used
in. The weight, drag and the type of model and how you intend to fly it are
all factors in determining the correct size propeller to use. Experimentation will be necessary to find the optimal size propeller for your particular
application. Ideally you want a propeller that the engine will turn in the
10,000 - 14,000 R.P.M. range, yet power the airplane sufficiently. Using a
propeller that is too small will cause the engine to run at too high an R.P .M.
Using a propeller that is too large will cause the engine run at too low an
R.P.M. and cause it to lug down too much. In both instances this can lead
to premature engine wear and eventual failure.
Propeller Size Recommendations
XL .25ARNV 9 x 5 9 x 6
XL .28ARNV 9 x 5 9 x 6 9 x 7
XL .32ARNV 9 x 6 9 x 7 10 x 5
XL .36ARNV 9 x 7 10 x 5 10 x 6
q Glow Plug Recommendation
Glow plugs can also make a big difference on the performance of your
engine. For the XL .25ARNV thru the .36ARNV we recommend using a
hot heat range glow plug intended specifically for two cycle engines. Do
not use a cold heat range plug. This can lead to erratic engine runs and
eventual engine wear and failure.
q Fuel Recommendation
Fuel can make a big difference in the way your engine performs. We recommend using two types of fuel with the XL .25ARNV thru .36ARNV
engines. For the break-in period you must use a fuel containing no more
than 10% nitro methane 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 1/2 gallon of the recommended
break-in fuel), a fuel containing 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 Castor 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 r un using a fuel containing only synthetic lubricants can cause engine failure. Using fuels with a Castor Oil
and synthetic blend of lubricants greatly reduces this chance.
HIGH & LOW SPEED NEEDLE VALVES
q 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.
q Low Speed Needle Valve
The low speed needle valve regulates the air/fuel mixture at idle and during transition from idle to full throttle. Turn the idle mixture screw clockwise 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, for
the XL .25ARNV and .28ARNV turn the mixture screw in until it stops.
From this point, turn the mixture screw out 3 turns. For the XL .32ARNV
and .36ARNV turn the mixture screw out until it stops. From this point,
turn the mixture screw in 3 turns. These are the factory settings for each
engine. These adjustments should be made with the carburetor barrel held
firmly open.
STARTING PROCEDURE
The XL .25ARNV thru .36ARNV can be started using an electric starter or
they 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.
q 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 hydrolocked state before applying the starter.
q 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 completely and choking the engine by putting your finger over the carburetor
opening. With the carburetor choked, “pull” the propeller through the compression stroke 2 - 3 times. This will draw fuel into the engine. Remove
your finger and pull the propeller through the compression stroke once to
check for a hydro-locked condition.
BREAK-IN PROCEDURE
Note: The XL .25ARNV thru .36ARNV are ABC engines. The cylinder sleeve is tapered at the top, causing severe resistance when the piston
moves through the top of the stroke. This is normal. When the engine
heats up to operating temperature, this resistance will decrease and the
proper clearance will be achieved. The br eak-in procedure will guide you
through the steps necessary to properly break-in your new ABC 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.
q 1) Turn the high speed needle valve out 2-1/2 turns from the fully
closed position.
Loading...