Hi. I was flying my Sig Wonder with an OS .25 FX engine (Cool Power 15%) this weekend and had some engine issues. It was 100 degrees. The engine was set to be slightly rich to the point that the throttle response was slightly boggy; however, any high speed-full throttle pass I attempted, the engine would stop. No problems at 1/4 or 1/2 throttle.

Does heat affect these engines to a great degree? I guess I can make it even richer, but I'd hate to have the engine bog down in flight and risk having it stop due to that.

The heat could very well be effecting the engine. Since you're not in a real marginal power situation, going a few clicks richer may not hurt in that heat (we've had the same heat here in Kansas also). But since you had good throttle response at 1/2 and 1/4 throttle, and not a full throttle, I'd look at the idle mixture being just a bit rich, or possible a fuel draw issue. You may want to check your fuel system to make sure you have don't have any kinks or holes in any lines. I recently had a problem with a plane that started running lean in flight and quit when I throttled it down. Found the pressure line had torn at the nipple on the muffler after I put it on.

I'm also assuming your engine is fully broken in. If not, you could need some more flight time on it before you'll be able to get the idle mixture dialed in. Been there, done that several times.

Hogflyer

[&o] well seems a lot of that is going around.

check your fuel system well, make sure your low setting is correct so your not loading it up. then try setting the high end. it will be a fine adjustment. you are right to keep it a little on the rich side. your a better man than i am. i have not braved the 103 degrees we have in the ozarks now.[&:]

I thought it could be a low-end issue. I'll check that tonight. Just to be sure, clockwise on the low-end screw leans, correct?

I have been flying in 110 you WIMPS

Lol, just kiden.

My engines aren't affected much by the heat. I tune them to peak RPM and back of a few hundred. I ALWAYS point the nose up to make sure it isn't leaning out in hover/uplines

Can you be a little more specific on how the engine quit. Do it warble or bog down before it died on you?


Edit:

The Low speed is tunned just like the HS needle. Clockwise leans it, counterclock richens it.

Just like the high-end adjustment, in is lean, out is rich. Just go very slow on the adjustment - like 1/8 turn at a time, run the engine up to full throttle for 30 seconds, the down to idle for 20 - 30 seconds and see how it responds to full throttle. Keep working like this and you'll eventually have it tuned in. It doesn't take much movement to affect your idle mixture.

Hogflyer

Well, the first time is stopped, I had been flying around for probably 3-4 minutes at 1/4 - 1/2 throttle, then I gunned it to full throttle while climbling slightly. Sounded like it may have loaded-up a little then stopped.

Second time, had been flying around for 2-3 minutes at 3/4-full throttle, then lined the plane up for a high-speed pass. Just as I was about to cross mid-field, the engine just stopped. No bogging or anything. Just stopped while at full throttle and full speed.

Do you have a filter in the fuel line between the tank and needle valve? Sounds like it is being starved of fuel when you give it full throttle. A partially pluged filter or some partial obstruction in the fuel line could cause this. Check for dirt in the needle valve also.

I would doubt that the high outside temperatures really affected it that much. I would look more at a fuel delivery or mixture problem. Up here in SW Oklahoma we have tons of 100°+ days every summer and fly my planes with no problems at all. Just set them to run a little bit rich and you won't have any problems with the heat.

Ken

Ken , it`s Down in SW Ok. not up. lol

For somebody in Texas it's always "up" to get to Oklahoma!!!!

Ken

Going to OK is ALWAYS a "downer".

In hotter weather, you actually need to run the engine at a slightly leaner setting. The warm air is less dense, and probably contains more water. Consequently, less fuel is required. Always follow the mantra of set it to peak, and then richen a couple hundred RPM. The difference for the running engine temperature when its in the air and being properly cooled will be insignificant.

Brad

If you live in Amarillo TX, most of Oklahoma is east and south to you.

Yeah, Cambo.. but it's a dry heat, right?

Good point

I guese it is 100 and humid in other parts of the states, AHHHH[&:]

Actually, we have had a few humid weeks from the mansoons but the clouds lowerd the temperature to 85

Foosball, if you are flying in Denton at North Lakes Park, then go on the weekend and find Gary Saba or John Larson. Those guys can pretty much figure out anything that could possibly be going on with that engine of yours. Great guys.

Drive south of Amarillo some time. Let me know how long it takes to hit Oklahoma.
BTW I have been to Memphis several times. Where is the good part?

David

[X(] [:@]

Ken

Gee, and here I was expecting some comment from Ken about Memphis............

Ok, taking another look at a map, I realize now that Amarillo is not farther north than most of OK, just farther north than some of OK. Amarillo and OKC are both on I-40 (old route 66) which goes east-west.
Perryton TX is only 47 miles away from Liberal KS. This town is definately more north than most of OK.

I'm still looking for the good part of Memphis myself. Been here 18 years now but I'll retire back in Texas most likely.