I have just completed building my 1st RC plane. It's a Tiger Trainer with a MDS .40 engine.

1st ? - I have started the engine, but it will not allow me to move the throttle past 1/3 to 1/2 before it dies. I have followed the the instruction manuel to a tee by setting the high speed idle 2 1/2 turns from closed and low speed idle the same way.

2nd ? - would the glow plugs being bad cause the engine to die once I pull the glow battery off?

Would anyone be able to point me it the right direction? Thank you in advance for any help

Usually if the engine dies when you pull the igniter off it does mean that the plug is bad. The engine may have come with a bad glo plug. I seen this happen before. But on the other hand the engine will die if the engine is very out of tune and then you pull the igniter off as well.

Usually if an engine is way out of tune i will tune it with the glow plug igniter on it. Then I will adjust the high end needle first to make sure that it is not to lean. Crank it up and rev the engine up some. Richen your high end until you can run the engine wide open. Let the engine sputter. I usually richen it a few turns just so I can run the engine wide open. Then from there slowly start to tighten your high end needle. Continue leaning out until it hits that high note and is maxed out. You will know if you went to lean because the engine will die out. Find the highest rpm with it right before it dies then back it off rich about 3 or 4 clicks.

Now to adjust the low end after the high end is set. Crank your engine up and start to run the throttle up and listen to how it sounded. If it sputtered and spit a bunch of fuel out, the low end is to rich. If it makes this hollow OOOOOOOOW sound then it is to lean. Trying to give an idea with my sound effects.

Then from there keep adjusting loosen or richen depending on how it responds to the settings you do. If it is to rich each time you lean in the low end the engine will rev up faster each time. Just add throttle and back off and see how it sounds. Keep adjusting until the engine revs instantly from idle to wide open. On the other hand if it is to lean keep richening it until it reacts correct to the fast throttle responses. From idle to wide open throttle.

Then from there remove your igniter and see how it reacts. It should stay running. Your rpms may drop a hair after you remove the igniter but it should not die out.


If any of you guys see that i forgot something or said something incorrect let me know. It is much easier to do this first hand than to type it out on steps.

^
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While I don't necessarily disagree with anything else you said... this was the important point.



My suggestion, CT46, is that you seek out an experienced RC'er if at all possible.
You'll likely need more help before this is over. The MDS engines are one of those
"hit-or-miss" brands, and you may get a good one out of the box, or you may get one
that requires some true experience and patience to get running properly.

Good luck though... and welcome to RC

Try three turns out to start.

Might sound dumb, but is the engine running the right way? When I first got my Irvine .53, it would consistently start backwards if flip started. (Even managed to do it once in a while off the starter, it would backfire, kick over backwards, and continue running.) When it is running like that, you will hear a lot of fuel bubbling up and anything past 1/3 throttle will bog it down.

C_Watkins I agree with you there. It is much easier to show first hand then to have it explained on here.

Maybe this will get him in the ballpark at least.

Also one thing I noticed while reading over what I said is that it is not necessary to tune the engine with the glo igniter on the engine. Usually you can do this with it off. I just added that to keep it from maybe keep it from dying while adjusting the high end. The low end requires the engine to be killed do to it is very hard to get to the low end needle while the prop is swinging. My mistake.

CT46,

Just a quick thought, seems like FlooredCOBRA had it about covered, I was just wondering if you had broken in the engine yet.

Seems like mine never run very well till I've driven a quart or two of fuel through them.

Start rich, just turn the needle 1/2 turn lean after start(to keep it going) leave the glo plug on and let it run a tank through. Do it again, by the third tank, you can start to lean it out and see what it can do.

When you first get an engine the piston is not quite the right size, it takes being heated up in the cylinder to get the tolerances right.

I know that you've just gotten your plane done and you want it in the air as fast as possible but this is kind of fun too.

Mount your engine on a 2x4 and C-clamp it to your picnic table. It will get you familiar with the engine and what the needle valve really does and what happens when you try different settings without having to worry about putting your plane in jeopardy. I know this first hand, I was so excited the first time I got my engine going, I learned by myself and I figured that one tank was good enough to break it in. The second time I fired it up I tried to fly it, the plane got about 100 yards away over the trees and the engine quit.

I never found that plane.

Now, when I can't fly, I just fire my engines just for fun, it makes a great noise and is just neat to play with. Needless to say, my engines are broken in, and you know what, the more they run, assuming it is correctly, the better they get.

Everyone is different I guess.

Good Luck!

As Always,
T -the prole-

This note is going out to all that reply'd.

Thank you - thank you - thank you. This will give me a place to start with. I really appreciate all of you. I have ran my first tank thru last night. Probably woke up a few neighbors in doing so, but thats what they get living next to an RC'er. haha

Really, thank you all for your input. Will def. post a note and keep you up on how its going.

Thank you again and take care all,

PS - happy RC'ing to all too :-)

Welcome to the addiction ct46: Just a thought here. I own 2 MDS 48 pros. I had a very similar problem with both. What it was is the high end needle, physically affected the low end needle. In short the high end was in to far when I adjusted the low end, so the low end was still way rich. I took them to the local engine guru and he had both of them running in about 10 minutes. Boy do I feel dumb! but this info is now in the memory banks. Try taking the high end almost all the way out, before setting the low end to factory recomendation. Then adjust the high end to factory rec. and take it from there.
Happy holidays
Garry

CT46, I just wanted to add my two cents in... I have just had the same problem with my new MDS 40 engine. I am new to this hobby and have read a lot of messages on this board about the problems with MDS engines. So, I tried to get mine started and after 3 hours of trying, one trip to the local hobby store(that gave no improved luck) and two days later, I finally got it to start and run. The engine was on a board at that time, so I let it run through 2 tanks of fuel one night and three tanks of fuel the following night at whatever speed it wanted to run at first, then constantly changing the speed towards the last few tanks of fuel. Today, I placed the engine back in the plane and it starts and I was able to adjust high and low speed needles correctly. So, with my expirience over the weekend, I now see why people want to throw these engines away at first, but all it takes is continued patience and a little luck. I am now convinced that these engines are great engines (after comparing it with my friends OS .40), but they require a lot more time than most engines to break in. So CT46, just let the engine run at whatever setting it wants to run, then after a couple tanks of fuel, get it adjusted correctly and you will be amazed at the results... I hope this helps a little and good luck...


-John Foshee

I didn't read all of the other posts but it sounds like it's too rich. Too much fuel is quenching the glow plug. Try turning the needle in 1/2 turn.

I have a MDS.78 that I could start alright but after a few tanks through it during breakin I tried to lean it out but I could not lean it out even after I turned the needle valve all the way in. I later read that the MDS had a proplem with their carbs, so I got a hold of Horizon Hobbies and I sent the carb back to them and they replaced it with the new C2 carb and now it runs fine. Give them a call. They seam to be willing to help guys out that have problems with one of these engines. Good luck!