I am new to four stroke engines and I am encountering a problem that I have not had with 2-stroke engines. I have a Great Planes Cessna 182 with an Enya .53 4-stroke engine. The engine starts up and runs beautifully but it keeps kicking the prop and spinner off. When ever I think I get it running just right and I take off it throws off the prop. I have an on-board glow plug heater on my plane, could that be creating a problem? Its running a little on the rich side, but when I try to lean it out it still kicks off the prop. I need some advice from you seasoned folk here. I am using Enya #3 plugs and Cool Power 15% fuel with Castor. The Prop is an 11X7. Also is there a way to secure the prop so it doesent come off when the engine backfires. I really get tired of having to search the fiel for my prop and aluminum spinner. So far I have been lucky enough to find it everytime it throws it. I am almost ready to put my TT .40 pro on it.

i think that you may be too worried about stripping the thread when tightening the prop,my advice is do it up tighter!,if you have enough thread put a locking nut on as well,if you don't then try a nyloc,also how about trying a larger prop for more flywheel effect,that should stop any backfiring,your engine should throw a 12" prop with ease.

I'd say you are more lucky that nobody has been hit by it. As bigchap mentioned, you don't have the prop nut tight enough. Use a 6" wrench and get it tight. There should be some type of jam nut on the prop shaft in addition to the primary nut. Backfiring is usually a sign that the engine isn't getting enough fuel. Do you have the glow driver on constant or does it disengage as the throttle increases? I suppose it's possible that the right circumstances could be igniting the fuel mixture too soon and causing the backfires. Try flying without the on-board glow but definitely get the prop nut tighter.

Thanks, This is good stuff. I use an Aluminum spinner therefore I am unable to put on a additional Jam nut or lock washer because of the prop spinner adapter. As suggested, put on a 12X6 prop and I have cranked it on real tight. My on-board glow heater is constant. I made it myself. I think I will get one that shuts off when the engine reves up a bit. I always thought if the engine was to rich it would backfire. I may be running it to lean.

The reason your Enya is kicking the prop is because it's too lean! This is a standard 4 cycle trait and seems to be more so with the Enya's. How do I know? 2 Enya R120's, 1 .90, 1 .60. I also own the following other 4 strokers, an OS .40, OS .91, Magnum .91, Saito 1.50 and a Saito 2.70 twin. The Saito is another real prop kicker when too lean.

Its a beautiful morning so equiped with this new information I anticipate a sucessful flight. I will run the plane rich and I changed my prop to a 12X6. I will report back the results this afternoon. Thanks Guys!

Still got a problem. I ran it really rich and got one good flight, but when I refueled for a second time and started it, it backfired and threw the prop and spinner and the spinner hit me in the face. luckly I was wearing sunglasses and it protected my eyes. This engine is not safe! I am going to have to ditch the aluminum spinner and use teflon nuts on the prop.

Use "Blue" Loctite to hold the nuts on. They will still come off but only when you want them to. Do not use the "Red" stuff as this is for permanent use.

Overtightening the prop or using nylock prop nuts are bandaids. You need to solve the problem. You are experiencing pre-ignition caused by too much heat inside the combustion chamber. That is usually caused by too lean a mixture, but if your on-board glow is constantly on, that may be contributing to the problem.

Overtightening the prop can also fracture the hub, causing the prop to throw a blade. You don't want that to happen.

First, disconnect the on-board glow. If that doesn't solve the problem you will have to richen the mixture.

The first question is; At what throttle setting does the "backfire" occur? If it happens at less than full throttle, then your idle mixture is too lean. If it happens at full throttle only, then you high speed needle is too lean.

The high speed needle on a high compression four stroke like your Enya needs to be richened so that the engine runs 300 or 400 rpm less than peak rpm. The idle needs to be on the rich side of smoothest idle too, so that the midrange stays rich during transition.

If that still doesn't solve it, you have a fuel feed problem and need to look for air leaks in the fuel system or carb/intake manifold.

Good luck, Jim

Don't use over about 5-10% nitro in Enya's.
They don't like the higher content! They will backfire!
Ray

Again Thank you guys for your help. I think I resolved the problem with each of your assistance. I changed my fuel to 10% since I needed some anyway. I found that I didn't have the problem when I shut off the on-board glowplug heater. I think it may have been causing the pre-ignition. I think the general nature of my engine is to be a little on the finicky side so I am just going to have to learn how to tune it right.

FYI: The cessna 182 is great flying plane!!! I did the most beautiful 3-point landing I have ever done this afternoon and in a 70 degree crosswind at that.

I'm flying a .46 size Sukhoi with an enya .53 4c. Mine is easy to start, idles slow, throttles great and runs at all plane positions...including hover. Your answers are correct..Enyas like lower nitro (no more than 10%), backfiring is a lean run condition common to most 4 cycles, onboard glow will change the heat conditions of the combustion chamber during the run (besides it is unnecessary).
These are anything but a finiky engine. They are very forgiving. Rich by 200 RPM, low nitro, enough oil and it will last until you tire of it. That should be a long time.

Enya 4c I own
.46, .53 (2), .80 (5), 1.2R

You are right Mike, this engine does not need the on-board glow system on all the time. The problems I am having I am sure are 99.9% operator error. I am glad to hear that this isn't a finicky engine. I am not familiar with Enya engines and when I bought I figured I was taking a chance since I was looking to buy an O.S. .52 four stroke. I couldn't pass up the great price I got the Enya for and it was brand new too.

What do you mean by "Rich by 200 RPM"? Would you mind sharing a few tuning tips with me regarding this engine?