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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: service@globalhobby.net

Using a 1/4" drill bit or a propeller 
reamer,  enlarge  the  hole  in  the 

propeller hub to fit the crankshaft. 

Slide  the  propeller  onto  the 
crankshaft, then slide the propeller 
washer up against the propeller 
and thread the propeller nut into 

place.  Notice  the  flange  on  the 

propeller nut fits inside the washer. Tighten the propeller nut firmly, then 

install and tighten the safety nut. When tightening the  nuts, use an adjustable 
wrench or a 4-way wrench. Do not use pliers.

WARNING

  If you are installing a spinner onto your engine, the spinner 

cone must not rub against the propeller. Allowing the spinner cone to 

rub against the propeller could lead to propeller damage and eventual 
propeller failure.

Your XL RFS series engine can be started using an 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.

 

WARNING ABOUT ENGINE HYDRO-LOCKING

If the engine becomes hydro-locked, do not force the propeller through the 
compression stroke. The excess fuel should be expelled from the engine.

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  Completely close the high speed needle valve until it bottoms out, then 

remove the glow plug from the cylinder head.

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  With a rag over the top of the engine, turn the crankshaft several times, 

using your electric starter or flipping the propeller by hand. The excess 

fuel will be expelled out of the engine and into the rag.

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  Check to make sure that the glow plug has not been fouled, then reinstall 

it, along with the gasket, and reset the high speed needle valve.

Low Speed Needle Valve

The low speed needle valve is preset from the factory for initial starting and 
break-in. 

Do not adjust it until after the engine is broken in.

 The low speed 

needle valve regulates the air/fuel mixture at idle and during transition from 
idle to full throttle. Turn the needle valve clockwise to lean the mixture or 
turn the needle valve counterclockwise to richen the mixture.  The low speed 
needle valve is preset from the factory, but minor adjustments may need 
to be made after the engine is broken in. 

To reset the low speed needle 

valve to the factory setting, follow these procedures:

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  Open the throttle barrel completely.  

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  While holding the throttle barrel open, turn the low speed needle valve 

clockwise GENTLY until it stops. From this point, while still holding the 
throttle barrel open, turn the low speed needle valve counter-clockwise 3 

full turns. This is the factory setting.

  

WARNING

  It is possible to adjust the low speed needle valve so lean 

that the engine will not draw fuel. The low speed needle valve should not 
need to be adjusted more than one full turn in either direction from the 
factory setting. If the engine does not idle or transition, reset the low speed 
needle valve to the factory setting.

STARTING PROCEDURE

Starting Using an Electric Starter

It's best to use an electric starter only when your engine has a spinner 
installed. The engine runs in a counter-clockwise 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 

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.

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PROPELLER, GLOW PLUG AND FUEL

Propeller Recommendation

The diameter and pitch of the propeller needed for the XL .52RFS engine 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 9,000 - 10,500 
rpm range on the ground, yet power the aircraft sufficiently. Using a propeller 

that is too small will cause the engine to run at too high an rpm. Using a 
propeller that is too large will cause the engine to run at too low an rpm, 

cause it to lug down too much and make tuning difficult. In both instances 

this can lead to premature engine wear and eventual failure.

PRoPEllER SIzE REcoMMEndATIonS

Use for

Break-In

12 x 6

12 x 5

12 x 7

13 x 4

Glow Plug Recommendation

We recommend using a medium to hot heat-range glow plug intended 

specifically for four-stroke engines. Do not use a cold heat-range glow plug 
and do not use a glow plug that uses an idle bar, or that is designed specifically 
for two-stroke engines. This can lead to erratic engine runs, difficult tuning 

and eventual engine wear and failure.

Fuel Recommendation

We rec

ommend using a fuel containing 15%~20% nitro and 16%~18% 

castor oil/synthetic oil blend lubricant. The same fuel can be used for both 

break-in and normal running. After break-in, a fuel containing 25% nitro can 

be used, but only if the fuel contains 18%~20% castor/synthetic lubricant.

IMPORTANT

  We highly recommend that the first gallon of fuel run 

through the engine contains either a castor oil/synthetic oil blend, or all 

castor oil. Do NOT use an all-synthetic oil fuel for the break-in period. 
After the first gallon of fuel, you can switch to an all-synthetic oil fuel, but 
only if the fuel is of high quality. For example, some 'sport' all-synthetic 

fuels use low-grade oils or oils with the wrong thermal properties (they 

do not transfer heat well), and do NOT work well in Magnum engines. 
If there is any question, it's always safe to use a castor oil/synthetic oil 

blended fuel, regardless of brand, as long as the oil content matches what 

is specified above.

HIGH AND LOW SPEED NEEDLE VALVES

High Speed Needle Valve

The high speed needle valve is used to meter the air/fuel mixture at full 
throttle. Turn  the  needle  valve  clockwise  to  lean  the  mixture  or  turn  the 
needle valve 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.

11 x 7 - 9

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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