I have my plane running but there is no power. It seems that there is more power when it is idleing then when I power up. In fact when it idles it will roll on the ground but when I throttle up it stops rolling. The engine is still running but there is no power. (MDS .40)

Is this the first time you have this particular engine running or have these problems just developed?

What have you done to get the engine running? The possible explanations for this are legion, from not properly tuning the high speed (should be adjusted to maximum RPM and then turned to the rich side a few clicks), to an improperly adjusted low end (rich low end loading up and then sputtering on throttle up), possibly air leaks in the fuel lines, foaming in the fuel tank, dirt or other foreign matter in the high speed needle, worn cylinder, bad glow plug, bad fuel....

Tell us exactly what you have (engine, fuel, glow plug, prop make and pitch), what you do to start, run, and tune the engine.

I know it gets repeated in every thread in this forum, but it applies. Take the plane and engine to a local club and find someone with experience that can help you. Otherwise you'll end up getting frustrated.

Good Luck!

Are you sure the engine isn't running backwards? When the engine is running can you feel the air blowing to the front of the plane? or to the tail of the plane? Please be careful around the spinning prop when you check to see what direction the prop is turning

Ken

From one Bricklayer to another Bricklayer. I would take my brick set, and brick hammer to it, and then break out the stihl demo saw! ....Just kidding! Sounds like a carb issue that can be be corrected with the help from someone who has some experience with mds engines. They do have a history of having some troubles, but there are also those who like them, and should be able to offer you some help. Sorry I couldn't be of more help. I just saw by your username that you are a bricklayer, and I am also a bricklayer, so I thought I would give you a bit of a hard time. LOL

hehe, It is a used MDS 40 engine that I bought from a friend. This is the first time I am trying to use it. My friend said that it worked fine for him. I would ask him to fix it but he lives very far away. The plugs are super something 2 cycle. I am using 15% fuel. The prop make is the basic 3 bladed prop. I don't know the pitch because I just clamped it onto the engine mount. Although it looks like it is pitching down slightly. By the way this is the first plane I have ever owned... if you couldn't tell. No it's no running backward. To get the engine running I give the needle valve two and a half turns, stick the glow stick on the plug and start it with the electric starter. it usually starts right up, although sometimes it takes a time or two before it starts.

Try a diffrent prop... Like an APC 10X6.. Maybe the "basic 3 blade" is a pusher prop?

I'm stumped

Just to make sure...when you increase the throttle you see the air intake open up right?

Roger that, it opens all the way. I am thinking that maybe it is a bad glow plug. Could this be it?

How soft is the prop?

Maybe its an electric prop...if you can bend the blades at all, get rid of it and get a good prop...if its too weak, the prop will actually flex the blades when you speed up....and twist the blades flat in the air...so they arent biting...

My guess is herein lies the problem. After you start the engine, you need to readjust the high speed needle to achieve peak rpm at max throttle, probably by turning it in (clockwise), and then turn it back out (richer) 2-3 clicks At 2 1/2 turns, your probably running the engine VERY rich, and it wont come anywhere close to providing good power. As this is your first engine, get someone to help you and show you how its done. Its not difficult.

Once you have it tuned, you shouldn't need to mess with the high end needle unless there is a large change in temperature or humidity. The 2-1/2 turns is usually recommended for new engines to make sure they are not run lean when first started.

Brad

It sounds too me like the prop is on the engine backwards. the curved part of the blade should be outwards and the flat side toward the engine.

I wish the prop were on the engine backwards, then it would be an easy fix. I will try adjusting the needle valve. There has been a sudden change in temperature here in the last couple of day. (Pocatello Id)

i t says in my modelers book that it should have a 10-6 ore a 10-7 prop running on 5% fuel.

It sounds like a Prop problem to me too. Just pick one up at the local hobby shop. Just get a cheap one since you'll probably break a few while you're learning (Like a Black Master Airscrew 10x6)

yes thats what i use verry good prop

If the plane rolls forward when you idle the prop must be pulling OK. If the Engine revs up when you throttle up and the prop turns faster and you get less pull then it sounds like the prop is too flexible and the pitch is changing. That's my best guess. Or, when you throttle up the prop is slipping on the shaft and is actually spinning slower. Or, the laws of physics have been repealed in Idaho.

I ended up fixing the problem this morning. Apparently there was too much gas and not enough air getting through the engine. I cut the needle valve back from 2 1/2 turns to just 3/4 of a full turn and the thing runs great now. I will be keeping an eye on it to see if it overheats now.

Borrow or buy a tachometer. Then, with the engine running at full throttle, set the high speed needle to peak RPM and then back it out a few clicks (about 200-500 rpm below peak to the rich side). This will help prevent overheating from lean running in climb or when the prop unloads.

Good Luck!