4-Stroke RC Engine
Operation and Maintenance Guidelines

 

 

 

 

The High Speed needle valve should be set so the engine runs 400 to 500 below peak RPM.An engine at idle should be turn over between 2,000 and 2,400 RPM.It is highly recommended that a tachometer is used to adjust your four stroke engine.Small differences in engine speed can be extremely difficult to judge by ear.

Once at Idle

If after going to idle the engine slows (lower RPM) then it is too rich (too much fuel). If after going to idle the engine speeds up (higher RPM) then it is too lean (not enough fuel). If the engine quits after a rapid throttle advance the low end idle adjustment is too lean.If the engine hesitates after a rapid advance but then continues to run, the idle mixture is too rich. 

Running Ever So Slightly Rich

Always ensure a four-stroke engine runs slightly rich. An engine will lean in the air and too lean of an engine will cause detonation and will likely throw the prop (along with the hub, prop washer, nut somewhere off to the side or front of the aircraft - about where you are!)Adjust it to be another 100 RPM lower (richer fuel feed) when in dry cooler weather. Two-stoke engines also need to run slightly rich but it is not as critical to get it "just right" as it is for four-strokes.

Post and Pre-Flight Checks

Check prop nut and safety nut is tight before every flight.After the initial 10 hours of running a new engine, check the engine to ensure nothing is loose and check the valve clearances. Do an inspection on the engine every 10 hours of running time to check for lose or worn parts. Once it reaches 50 hours of running, tear it apart and check everything. (If you do not have a good clean undisturbed place to take apart and leave the many, many little pieces of an engine lying around for a few weeks, send it off to a repair shop).

Glow Plug

The OS Type "F" is a long plug. This was the first plug made specifically for 4-strokes. A four stoke plug is longer so that it extends further into the combustion chamber thus getting and staying hotter. This allows it to retain its glow during the three strokes that the engine is getting ready to fire on the 4th. Never use a Type "F" plug on 2 cycle glow engines. The piston may hit the plug. 

Fuel

So many choices. Any fuel with 10% to15% nitro will work. You do not have to buy special 4-stroke fuel as the fuel you run in the 2-Stroke is just fine. 

Props

Follow the manufactures recommendations.  Generally choose a prop that keeps the RPM between 8,500 and 10,000 RPM (rough area where most reach peak horsepower) and it should fly well.

After Run Oil

Owner's choice, Air Tool Oil works, as does Marvel Mystery Oil, Mobile 1, and Synthetic Engine Oil.  WD40 doesn't work. Don't use it.