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Thank you for choosing a Magnum XL RFS series aircraft engine. The 
XL .52RFS is a single cylinder, four-stroke engine incorporating an aluminum 
piston, iron ring, and steel sleeve for long life and high power output. The 
engine features a dual needle valve rear updraft carburetor for precise 

fuel/airflow metering, dual ball bearing-supported crankshaft and camshaft, 
dual bushing-supported connecting rod, and a high-flow quiet muffler. Your 

Magnum  XL  RFS  series  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.

Magnum XL RFS series model aircraft 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 XL RFS series model 
aircraft 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 or misused, 
or if you fail to observe proper safety precautions while using it.

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  Keep spectators, especially small children, at least 20 feet away from the 

engine while it is running. 

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  Mount the engine securely in the aircraft or on a suitable engine test stand 

to run the engine. Follow the mounting instructions in your aircraft's 
instruction manual or on the plans for individual mounting recommendations. 

Do not clamp the engine in a vise to test-run it.

  

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  Use the recommended size propeller and follow the proper procedure for 

mounting the propeller. Use the correct size wrench to tighten the propeller 
nut and the safety nut. 

Do not use pliers.

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  Inspect the spinner, propeller, propeller nut, and the safety nut on a regular 

basis, looking for any signs of nicks, cracks or loosening.

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  To stop the engine, adjust the throttle linkage to completely close the throttle 

barrel and therefore cut off the fuel/air supply. You can also pinch the fuel 

line to stop the engine, but only if it is accessible.

 Do not throw anything into 

the spinning propeller or attempt  to use your hands to stop the engine.

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  While the engine is running, stand behind the engine to make any adjustments 

to the needle valves. Do not reach over or around the propeller. Do not lean 
toward the engine. 

Do not wear loose clothing or allow anything to be 

drawn into the spinning propeller while the engine is running.

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  If you need to carry your model while the engine is running, be conscious 

of the spinning propeller. 

Keep the aircraft pointed away from you and 

others at all times.

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  Do not use a tight-fitting cowl over the engine. It can restrict air from flowing 

over the engine, which could result in engine damage from overheating. 

For proper cooling, the total cowl air-exit area should be 30% greater 

than the total air-intake area.

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Global Services 

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18480 Bandilier Circle 

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Fountain Valley, CA 92708 

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Phone: (714) 963-0329 

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Fax: (714) 964-6236 

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Email: [email protected]

For product warranty information, please refer to the

warranty card provided with your engine.

Magnum XL RFS series engines are distributed exclusively by Global Hobby Distributors

All contents copyright © 2009, Global Hobby Distributors, September 2009

Displacement .............................................

52ci (8.53cc)

Bore / Stroke ..............................................

23mm / 21mm

Practical RPM ............................................ 2,000 - 10,500

Weight w/Muffler

 ........................................

15.7oz

Crankshaft Thread Size

 ............................. 1/4-28

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  Ringed Piston Design for Long Life and High Power

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  Dual Ball Bearing-Supported Crankshaft and Camshaft

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  Dual Bushing-Supported Connecting Rod

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  High-Flow Quiet Muffler

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  Dual Needle Valve Rear Updraft Carburetor

Engine Orientation

Your XL RFS series engine can be orientated in any position on the firewall. 

Keep in mind that when the engine is mounted inverted, carburetor 
adjustments will need to be made differently and the fuel tank may need to be 

lowered. (See fuel tank size and orientation to carburetor on the next page.)

XL .52RFS AIRCRAFT ENGINE

SPECIFICATIONS AND FEATURES

INTRODUCTION

BECOMING FAMILIAR WITH YOUR ENGINE

If you are familiar with the operation of four-stroke model engines or just 
can't  wait  to  run  your  new  engine,  please  read  through  the  Quick-Start 
Guide included. The Quick-Start Guide will help you get started right away 

and  also  includes  recommendations  for  items  required  to  run  your  new 

engine. We do recommend reading through these Operating Instructions 
in their entirety to familiarize yourself with the features and operation of 
your new engine. We have also included a Troubleshooting Guide should 
you encounter any problems. Please use the photos below to familiarize 
yourself with the components of your new Magnum XL RFS series engine.

CAUTION - PLEASE READ BEFORE USE!

ENGINE INSTALLATION

XL .52RFS

RINGED FOUR-STROKE

AIRCRAFT ENGINE

P/N 210851

*Due to continued manufacturing changes 

and improvements, your engine may differ 

slightly from that shown.

OPERATING

INSTRUCTIONS

Valve Cover

Muffler

Pressure Nipple

Pushrod Tubes

Camshaft

Housing Cover

Crankshaft

Prop Nuts

and Washer

Drive

Washer

Breather Nipple

Intake Pipe (Manifold)

Carburetor

Cylinder Head

Backplate

High Speed Needle Valve

Low Speed

Needle Valve

Throttle Arm

Rotor Bolt

Idle Stop

Screw

Fuel Nipple

Detent

Spring

Summary of Contents for XL .52RFS

Page 1: ...he engine is running l If you need to carry your model while the engine is running be conscious of the spinning propeller Keep the aircraft pointed away from you and others at all times l Do not use a tight fitting cowl over the engine It can restrict air from flowing over the engine which could result in engine damage from overheating For proper cooling the total cowl air exit area should be 30 g...

Page 2: ...during flight Idle Stop Screw and Rotor Bolt The idle stop screw adjusts the closure of the throttle barrel idle speed We recommend adjusting the idle stop screw to allow the throttle barrel to close completely This will allow you to adjust the idle speed via your transmitter therefore you will need to set up your transmitter throttle trim lever to keep the engine at a low idle when the trim lever...

Page 3: ...ckwise direction 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 its own Priming the engine prior to using an electric starter can cause the engine to hydro lock flood Turning the engine over with an electric starter while the engine is flooded can cause extreme damage to the engine and or cause the ...

Page 4: ...etween a 200 300 rpm drop q 3 With the engine running at full power carefully lift the nose of the aircraft about 45º into the air The mixture should not become too lean but you may hear a slight increase in rpm If the engine sags or loses rpm when you hold the nose up the mixture is too lean If this is the case slightly richen the mixture and follow the test once more IMPORTANT Rpm will increase ...

Page 5: ...underbolt HP Glow Plug Product Number 115480 The Thunderbolt HP glow plug is designed specifically for four stroke engines and produces low idle speeds smooth transition and cooler running temperatures The glow plug is also very durable and able to withstand repeated use day after day Propeller APC 12 x 6 Propeller Product Number LP12060 We have found that XL RFS series engines run best using APC ...

Page 6: ...e valve set too rich C Set high speed needle valve to leaner setting D Low speed needle valve set too lean D Set low speed needle valve richer E Low speed needle valve set too rich E Set low speed needle valve leaner F Air leak in fuel system and or engine F Replace fuel lines and or tighten all engine bolts G Propeller too large G Use propeller within the recommended size range H Valves out of ad...

Page 7: ...0 80841 Lock Washers 2 M3 281166 12862 Needle Valve Seat Assembly 281174 80719 Rocker Arm Retaining Bolt M3 x 16mm 281210 52111 Backplate Gasket 281307 52134 Carburetor Retaining Bolts M2 5 x 20mm 281308 12518 Intake Pipe Camshaft Cover Bolts M2 5 x 8mm 281403 12109 Camshaft Ball Bearing 281417 52109 Front Ball Bearing 281418 52110 Rear Ball Bearing 281507 160120 Cylinder Head Bolts M3 x 18mm 2815...

Page 8: ...ard the front of the engine of the 6 o clock position q 4 Reinstall the camshaft housing cover RESETTING THE TIMING MAINTENANCE Engine maintenance should be done on a regular basis to ensure that you keep the engine running in top form especially over time Following these simple maintenance practices will ensure the long life and dependability you expect from your engine l Avoid running the engine...

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