Engine Break-in
Engine Disassembly
Engine Problems

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I can be reached at rcmodeling@gmail.com. Please feel free to contact me so we can talk about one of our favorite hobbies!

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Below are some safety items that although seem elementary still need to be repeated regarding propellers and their use.

  1. Install the prop with the curved side of the blade facing forward and tighten the prop nut or bolt with the proper size wrench.
  2. Recheck the tightness of the nut or bolt often, especially on wood props which tend to compress and loosen more often.
  3. When starting the engine, keep spectators at least 20 feet clear of the model and out of the path of the propeller.
  4. Keep hands away from the prop as much as possible. Use a chicken stick or and electric starter.
  5. Keep face and body out of prop arc as engine is started and run.
  6. Make all adjustments from behind the prop except on pusher prop installations.
  7. Never throw anything into the prop to stop the engine. Use a kill switch or pinch off the engine's fuel supply.
  8. Discard any prop with nicks, scratches, splits, cracks or any other sign of damage. Never attempt to repair, alter or bend a prop.
  9. Don't run an engine in areas of loose gravel or sand for the prop can throw such material into your face and eyes. It's not a bad idea to wear eye protection.
  10. Keep loose clothing, shirt sleeves, and other such items away from the prop and avoid carrying objects that can fall into the prop such as pens, screwdrivers, etc.
  11. Be sure to keep the glow driver wire out of the prop path.
  12. If a spinner is used, be certain that it's edges are not in contact with the propeller blades.
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The Pinch Test

If you pinch the fuel line and the engine speeds up, it is on the rich side of the adjustment.  HOW MUCH is speeds up shows how close you are.  If it speeds up a lot, you are rich.  If it speeds up just a little, you are just right.   If it doesn't speed up, you are just going lean.  If it slows down, you are LEAN

This test temporarily starves the engine for fuel ,and is reliable to test for a too-lean condition.  At full throttle, quickly pinch the fuel supply line.   The engine should momentarily increase RPM's before starting to die.  It it starts to die immediately, then it's already too lean and should be adjusted.

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Having Trouble with your Super Tiger carb. adjustments?

Here is the info ( I realize some of this is obvious, but it is straight out of the instruction book). This booklet is supposed to cover the G-34 to S-90K. Hope it helps you out.

Initial Setup and Break In (ringed engines)

Gently turn the high speed needle clockwise until it stops. Do not tighten it. Then open 3 turns. Do not worry about setting the idle mixture screw at this time because it has been set at the factory.

Turn on Tx & Rx and fully open the throttle. Place a finger over the intake and turn the propeller over a few times (counterclockwise) without the glow charger attached. Watch the fuel line. You will see the fuel come up to the carburetor. Once the fuel reaches the Carb., turn the propeller 2 more revolutions. Remove your finger from the intake, and briskly flip the propeller to work the fuel into the engine.

Attach the glow charger.

Close the throttle to 1/2 to 1/3 open.

If using a chicken stick to start the engine, flip the propeller counterclockwise using quick flips. If the engine fails to start after 10 flips it may not have enough fuel in the engine. Remove the glow charger and repeat the choking process.

If the propeller becomes difficult to rotate, it is flooded with fuel. If flooded, remove the glow plug, turn the plane upside down, and flip the propeller backwards a few times, allowing the excess fuel to drain out. Reinstall the glow plug , attach the glow charger and try starting the engine again.

If using an electric starter, do not attempt to start a flooded engine as it can damage the connecting rod.

The engine should start and stay running, although it may be slightly rough at this time. This is normal. Allow the engine to warm up for 15 to 20 seconds before removing the glow charger. Let the engine run at this throttle setting for 30 seconds and then open the throttle fully.

The engine should be running at full throttle but somewhat rough, with alot of oil being discharged from the muffler. This is because the engine is running very rich. Run the engine at this setting for 5 minutes.

After five minutes, you can start leaning out the mixture by turning the high speed needle clockwise. Never turn the needle more than 1/8 turn at this point.

To determine if the engine will accept a leaner mixture, give the fuel line a quick pinch and release...just pinch the fuel line and let go. You should hear the engine RPM increase a bit.

If the engine increases in RPM, you can lean 1/8 of a turn. Allow the engine to run 1 minute at this setting.

Now give the fuel line a quick pinch and release. Wait thirty seconds and do this again. Do this five times.

If the RPM increases all 5 times, lean the high speed needle 1/8 of a turn. Wait one minute and start the pinch and release series again. If the engine doesn't increase in RPM when you pinch and release, wait one minute before you try the pinch and release again.

Don't lean the high speed needle until you get an increase in the RPM every time you pinch and release the fuel line.

Keep repeating the pinch and release method until the engine does not change RPM when you pinch the fuel line.

You've leaned the engine as far as possible. Do not ever lean the engine to the point the the Rpm's go down when you pinch the fuel line. For flying you want to set the mixture so that you get an increase in RPM when you point the plane up or pinch the fuel line. If you hear the Rpm's decrease when you pinch the fuel line, Immediately open the high speed needle 1/4 turn and try again.

At this point you can adjust the idle setting.


Initial Setup and break In (ABC Engines)

The ABC engine break in process is similar the the ring engines with one major difference. The ABC engines are not run as rich as the ringed engines in the early process.

Choke and start your ABC engine in the same manner as detailed above in the Ringed Engine section.

Let it warm up for 30 seconds and advance the throttle to full open.

Now slowly lean out the mixture while you listen to the engine. As you lean the engine, you will hear it increase in RPM. At some point, you will hear the engine sound like it is jumping up and down in RPM. The exhaust note will be jumping up and down in pitch. You want to continue to lean the engine until it is running at mostly the higher pitch sound, with just an occasional break to the lower pitch sound. Let the engine run at this setting for 5 minutes.

After 5 minutes of running, lean the engine using the pinch and release method as detailed in "Initial Break In" (ringed engines).


Idle Mixture Setting

The idle mixture is adjusted with the brass screw that's located in the center of the throttle arm. It operates in the same manner as the high speed needle. Clockwise leans it out and counterclockwise rich-ins it up. It needs to be open at least 1/2 turn.

The basic adjustment of the idle needle has been set at the factory and should require little adjustment, if any. Use the same pinch and release method to determine if the idle mixture can be leaned out. You may have to hold the pinch a little longer because the fuel flow is less at lower RPM ranges.

The best way to adjust the idle mixture is to have the engine running at full throttle, and slowly decrease the throttle to less than 1/2 open.

Once the engine has been throttled back to less than 1/2 throttle, try the pinch and release method. The engine should increase in RPM slightly. This means you can lean the idle mixture a bit, about 1/8 of a turn.

Reduce the throttle a little more and repeat.

You should be able to work down to a nice slow idle.

The Carburetor should be about 1/32" to 1/16" open when the engine is idling properly.

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Engine Overhauls

1. When you take the engine apart and you want to get those nasty varnished in place cylinders and bearings out to clean or replace just put the crankcase (with the stuck parts) in the oven on the bottom with the oven set to a high "baking" setting. Must be baking so the lower heat element is hot.

Do not put parts that have rubber or silicone parts; i.e. carb, O-rings, gaskets in the oven.

Bake for 3 to 6 minutes. Pull the crankcase out with vise grips or burn your hands, your choice. Watch that the bearings or cylinder do not fall out when removing the engine. If they do not come out easily bang the back of the case on a block of wood and they should fall right out. If not try heating longer.

2. Nasty, dirty and varnished engines tend to run hot. High temperatures will reduce engine power and life. To clean the crankcase and cylinder head of vanish first remove all parts, i.e. crank, piston, liner, bearings and anything else that is loose. Take the crankcase and cylinder head and wash oil and lose dirt off with hot water and soap, "This will not hurt the cast aluminum parts". Then dry with a rag and soak in a jar of good old paint stripper from a hardware or paint store. Use a fine stiff acid brush or an old tooth brush to remove stubborn varnish.

CAUTION! DO NOT GET THE STRIPER ON SKIN, IT'S PRETTY CAUSTIC! USE RUBBER KITCHEN GLOVES AND EYE PROTECTION. (This is a serious warning I used some of the commercial cleaner sold for cleaning engines. It did not seem all that bad, did not burn my hands or anything, so I did not use gloves two days later my hands looked like they had been sun burned and most of the first layer of skin pealed off. Editor)

Also in time the tooth brush will melt if you don't wash the stripper out frequently. After you have got all the varnish off the engine rinse all the stripper away with water and dry the part with a rag then coat with a good after run oil. I use air tool oil and it works fine. ( NOTE: the reason you want to use air tool oil is that it will not attack the o rings and other silicone parts in the engine like normal oil will. Don't forget most of our engines are designed to burn alcohol not oil based gasoline.: Editor )

3. To install a new rear main bearing, drill a hole in a hard wood block large enough to put the threaded end of crank in. While inserting the crank through the case (with rear bearing in place on the crankshaft)

then use a long punch or dowel through the back of the crank and tap with a hammer until the bearing is seated.

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How to adjust the top end*:

  1. Close needle valve, then open 2 full turns.
  2. Make sure you have a good glow plug.
  3. Start engine, and run at full throttle.
  4. Slowly close needle valve to lean the engine.
  5. Pinch the fuel line briefly between every couple of clicks to see if the RPM will rise any further.
  6. If the engine picks up RPM, continue leaning.
  7. A properly adjusted engine will pick up just a little when you briefly pinch the fuel line.
  8. If the engine immediately dies when you pinch it, it is to lean.
  9. As a final check, hold airplane vertical to ensure the engine will not lean out.
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How to adjust the low end*:

  1. The procedure resembles that of adjusting the top end.
  2. Close low end needle or screw, and then open 2-3 turns.
  3. Start engine and run at full throttle for at least 10 seconds.
  4. Bring engine to idle (about 2500 RPM) and let idle for 10 seconds.
  5. Pinch fuel line and hold.
  6. If the engine speeds up and then dies, the low end is to rich.
  7. If the engine slows down and then dies, the low end is to lean.
  8. Turn needle or screw 1/4 turn in the direction required and repeat process.
  9. Ideally when you pinch and hold the fuel line while the engine is idling, the engine will not gain or loose any RPM before it dies.
  10. When you get close to this, make smaller adjustments to really dial it in close.
  11. In some cases, you will have to readjust the top end while adjusting the low end. Always make sure the top end is properly adjusted before adjusting the low end.
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Air-Bleed Screws


When adjusting air-bleed carburetors (the ones with the little hole in the front), a good rule to remember is the word “richen”. Split this word in half (rich-en), and when you want the carburetor rich, turn the screw in. Of course leaning the carburetor would be turning the screw out.

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Engine Cleanup with Antifreeze
I finally tried this anti-freeze technique and it sure does work! I used a crock pot. I took apart everything and dumped everything in, (expect the gaskets and o-rings). Adjust the heat to about 170 degrees F. I left it on about 4 hours and then let it cool down for a few more hours. After it was cool, I used a piece of tubing to siphon most of the anti-freeze into a jar. Then I got a few paper towels and dumped everything onto them to soak out the excess. All the parts were clean except for a couple really stubborn black heavy spots on the head. They would have gone maybe in another hour but it was clean enough at that point anyway. I rinsed everything with soapy water and used an old tooth brush on some carb parts to remove some white residue that came off easily. At the bottom of the pot was this gelatinous gooey mass that looks like something that might become a new life form with a little more organization. It must be all that cooked castor oil but swelled up with glycol? Hey chemists, what's going on in this 'process'?? (Is it like an affinity thing like polypropylene and oil?)
BTW - Wear plastic gloves!
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Developed by Geistware of Indiana© ., 1999.
Updated December 25, 2002