painly

My Feedback: (4)

this engine is pretty much new, but whenever im in the air for about 5 or so minutes, it starts to drop rpm speratically, and then most times will end up sompl;y stalling when im turning away from the wind. anyone know what gives? bad plug maybe>? i got it on the ground and held it in all angles and it never stalled, i just dont know.

thanks

Steve Collins

My Feedback: (8)

Sounds like you may have an air leak inside the tank. Since you said it flies about 5 minutes before the problem occurs, what I think is happening is that the leak is covered with fuel until the fuel level burns down enough to expose it. The first place I suspect the leak is in the pick-up tubing inside the tank near where it is connected to the brass tubing. Always make it a practice when setting up tanks to file off any sharp edges on the brass tubing.

The second possible source of air leak is at the stopper. Make sure the stopper is in good condition and that it is really tight.

If the problem is not cured by these easy to fix suggestions, then another possibility is that the needle setting is a little too lean. Symptoms of too lean are when an engine runs strong at first but then noticeably starts slowing down.

Spicoli

It sounds like it is leaning out.Run a full tank of gas through it on the ground and watch the fuel line going into the carb.Make sure there are no air bubbles in the fuel line.If you see air bubbles that is your problem.

painly

My Feedback: (4)

thanks for the reply's, i will give thsoe a shot

painly

My Feedback: (4)

well iw ent out today and ran a tank of fuel through it on the ground. no bubbles at all in the line, and i made sure to not run it to lean. what i found was when i would run it upside down with the fuel supply getting close to empty is when it would stall. (even half empty). now im fairly new to this. im thinking maybe this is comming sense to not do inverted flying when the fuel is love, or perhaps my klunk line is to long and not letting it move around easy. one thing is foresure, the lines are fine.

the setup in this plane, if i was to get at teh tank, would involve alot of work , although my engine seems fine, it woulda been much easier to rebuild it then get at the tank

any more suggestions/comments!

Spaceclam

it actually sounds like it is overheating and siezing up. are you using a pitts style muffler? because increasingly more, pitts mufflers become too restrictive, so that it looses a lot of power when running, and does not expell as much heat as it would with the stock muffler, causing it to heat up. keep in mind, a big chunk of the cooling effect fomes from the cool fuel entering the engine, which to act effectively requires the maximum expulsion of heat from the engine. 5 mins sounds like a good amount of time, and that is the only thing that i can think of which will quickly drop the rpm, and then just stop running. try running a tank or two with minimal times inbetween fueling (ie jsut enough time to fuel up) if it does the same thing after about 5 mins, that is brobably the answer. i will bet the reason it does not stall at any angle you hold it at is becaue you don't hold it there for 5 mins.

Andy McC

It sounds very similar to a problem I had recently. At first I thought my engine (OS 46fx) was running lean. On the ground it would run perfectly but after a few minutes it would run erraticaly, if at that point I pointed it straight up the engine would sometimes stop. So I would keep setting the engine a little richer until it was obviously sloberingly rich and still no result.

I had considered the clunk but the tank was difficult to get at and I could hear the clunk moving around when I shook it. However, after checking everything else I had to take the tank out and...

discovered the problem straight away. The clunk line had managed to twist on its self so that although it was lying on the bottom of the tank and would move around when rattled it was half way between the front and back of the tank. It meant that the engine ran well on a full tank but as the fuel got lower and moved around in the tank the engine would become erratic and finally stop in certain nose up attitudes. The clunk line ( supplied with the ARF kit) was too flexible. I replaced the line with proper quality tubing and have had no problem since.

Hope this helps, sorry for being so long winded.

painly

My Feedback: (4)

spaceclame, thanks for the input, but i forgot to mention, when i have it inverted like i was saying, i started getting the bubbles in teh line. and now that i think of it, its only when im banking hard in fly and comming out that i get the sluggish rmp drop and then pick up, with must just be bubbles.

i think you hit it on the head andy, im gonna rip out the tank

its funny cause i think i have another tank here with the same problem, when i built a few kits this year, i was completely new to the sport, and though a little extra line would be better, ha, was i wrong. i think i will also put in the tuffer line.

thanks all, ill let you know how it turns out

daven

My Feedback: (1)

My guess is your trying to spin to big of a prop on that engine.

What size prop and make are you using?

painly

My Feedback: (4)

its a 10x6, what teh factory recomended, and like i said i have no problem unless im upsidedown

painly

My Feedback: (4)

got it apart today (cut out the firewall), and sure enough, the tubing inside was too long, not only that, but the hose inside was slipping off for some reason. i shortened and used a little bit of epoxy at the base of the lines to keep them on, hope i dont have troubles with the epoxy down the line.

phughes

Stupid question, but why are you not making a way to access the systems of your airplane? Things like tanks, engines, switches need to be accessed from time to time. having to cut out a firewall is not an acceptable solution. Not being a smart ass, but you really need to give yourself the option to correct a simple problem . . .simply!

painly

My Feedback: (4)

ya i know. i built this plane from scratch without knowing anything about rc's. the only thing thats hard to get at is the tank. this plane is comming close to its end anyways. ive learnt on it and it has a few bumps, im just waiting for it to do the big crunch, then i can try flyign some of the other ones ive made. i also have another plane here that i build from kit, that does not allow access to the tank, once again if i knew then what i know now, ....

DBCherry

My Feedback: (4)

I don't think the epoxy is going to help inside the tank. The fuel will eventually soften the epoxy.

When I install that "clunk" line, I use a short piece of brass tube in the middle. It keeps the line from bending forward on itself.
Dennis-

Spaceclam

you can also try cutting a small piece of fuel line, and streaching it on top of the fuel line connection. it is very hard to get it so slip off that way. also, if you use epoxy, you probably will never get it off again if you need to. i would try the fuel tubing thing. it is like using a wire tie

painly

My Feedback: (4)

that tube over thing is a great idea, so is the metal in the middle. i took the epoxy off after i typed that message and got some wire and wired it fairly well. put everything back together (epoxied the firewall back on), tested it, and viola, not a bubble at any angle, went out, and it wouldnt take off, in fact i wrecked a propeller trying to get it off the ground, take a closer look, and the epoxy must not have cure good enough ( i should had know better), and tehe engine weight gave a downward angle ont eh firewall, that combined with todays absolute zero wind, gave for no take off, however the prop is replace and the engine is shimmed up, hopefully the wind will be minimal tommorow also (we have had a really windy season, yesteday it reached 50mph)

thanks all!