Hi,
I have an MDS 48 PRO and it is still on the bench!! I can`t tune it properly or it just won`t keep it, one of the two. Is anyone else having these problems, I`ve heard that they are hard to tune. If anyone has some advice and tips for me, it would be most appreciated.

Many thanks and blueskies Nige.

Put some foam under the tank to prevent fuel foaming. Foaming fuel will make it impossible to set correctly.
If your engine runs better with the glow ignitor on it could be a couple of things. Make sure your glow plug is good. Your mixture is much too rich, or your fuel is old. Not sure how old your fuel is or your glow plug.
Check your carb for debris in the fuel system that can cause erratic running.

Richard

There have been many threads about the MDS engines. One guy's engine runs perfectly and the next guy cannot get his to run.

A lot of the problems come from air leaks around the base of the carb.

MDS engines also tend to unload more in the air than a OS or Irvine for example. Therefore they need to be set a little richer on the ground to allow for the unloading in the air.

Everything that w8ye and YUKONFLYR said plus

Form personal experience a lot of these engines are supplied with a poor o'ring on the carb mounting. Remove the carb and replace the o'ring that seals the carb to the engine. At the same time I like to put a little high temp silicone on the carb retainer just to make sure that it doesn't leak air either. We have one particular one that was given to us because the owner gave up on it doing exactly what you describe - a simple change of o'ring and it now runs quite sweetly.

It might be helpful if you would describe what the engine is doing. The one I ran for several years before I sold it was a great performer. You are using low to "0" nitro fuel, aren't you? What have you done to try to get it to run? Has the engine been run in, yet?

Hi,
Thanks for all the replies, I will try them all. In answer to the question on what I`m doing and the fuel that i`m using is, I`m new to i.c. and i`m going off the user manual so i`m probably doing something wrong, I use an ENYA No 3 glow plug which is what they recommend and the fuel has all the ingredients that they recommend plus what my local model shop told me. I just find it wierd that when I leave the glow starter on, the performance is brilliant and no matter how much throttle I give it, it does`nt matter. Soon as I take it off it either cuts out or when I give it full throttle it dies or it begins to chugger.
Cheers Nige.

Nige,


Could I assume you are trying to run 10% nitro in that engine???
That is what the gallon just says...

That engine is Eastern Block. Only 0-5% nitro, or it will run badly.


A lot of castor oil in the fuel will also be necessary. That jug is only 15% all synthetic EDL...


Just make it easy on yourself and mix 1 part castor oil with four parts methanol. Use that for fuel.

I'm not sure about the Enya plug numbers and how they correspond to OS's numbers. My MDS 48 would do the exact same thing with any plug besides an OS A3. (It would run on an OS #8 but would dead stick on rare occasions, mostly when you did a missed approach and hit the throttle quickly) I also have to run the idle mixture as lean as possible and still have it stay running in order to get a decent mid range. I am not sure how they handle MDS's in the UK but the ones delivered to the US are set up for 10 to 15% nitro. (Someone told me about running low nitro in mine because of it being an eastern bloc engine and when I tried it many problems came up so I went back to 10% and all was well again. Later I was told the US bound engines are set up different because of the fuels we tend to run.) It doesn't like little props (It's not a screamer) and I run an APC 11X7 on mine but it will also turn a 12X4 or 5 pretty good. The most important point of my ramble is mine would not run well on any plug other than an OS A3 and on that plug it runs very good. Good luck with yours.

Edited to add: Like Dar says they like Castor in the fuel. I run Omega in mine which is 70/30 blend synth to castor. Also, mine had a lot of pinch when new and took a gallon or so to loosen up and that's when it really started to run sweet. It still has a lot of pinch but not like when it was new when I had to use a hair dryer for the first couple of tanks to start it.

Jez,


Nige is in the UK, so he must have the Euro version...

I believe no nitro is what the doctor ordered.

As to Enya plugs, their #3 is the hottest, like OS' A3.
It is also what they recommend for four-stroke engines, despite not having a 'shrouded' end.

Their #4 is like the OS #8...

Their #5 is like the OS A5.

But...

Enya plugs are real long-reach; not mid-reach like OS plugs.

Sorry Dar, I was in the middle of editing when you posted. Since the UK guys can get higher nitro fuels more cheaply than some other places I thought they might be shipping them the same engines we are getting. If he has the eastern bloc engine then you are 100% right on with nitro rec. and his most likely problem is too rich on the low needle.

Heres the plain truth. A FOX RC long Idle bar plug a must. Any other plug will run hot. 5% nitro is the max unless you put a shim in. They have to be a little rich on ground cause they will unload in the air. If you can't live by these 3 rules sell it..............I'm not kidding.....Don't waste your time or ours...............

Hi Nige

I see you have a nice setup with your engine.

ALso, if everything is set properly you shouldn't have problems with your engine, so I think as people has said, there should be a problem regarding air leaks in the carb or backplate, you should look for them. Also, if your engine is set for high nitro (lower compression= more head shims) you shouldn't have any problems running on low nitro, despite a little less power. THe inverse I think will give you some problems but I think the engine will run anyway.

Tighten head bolts and so, and also try lower nitro fuel, using straight castor/methanol fuel as said before is a good starting point. Your problem must be a minor one, not a problem that makes the engine deserve a bad reputation.....do a search in your engine and let us know.

Jorge

Mine runs great with a Fox idlebar plug, Fox 5% fuel with 20% castor and a Graupner 12x5 or 6. Those engines like to work hard and most MDS engines like to be run as if they were a larger size, for example, treat the .78 as if it were a .91, the .68 as if it were a .75, etc.

Hi!
You are simply running it with too much nitro!
0-5% nitro is what you should run and an OS 8 or Enya 3 glowplug works good, as many more plugs do.

MDS has allways stood for "Many Dead Sticks" in my book. Sell it and buy a decent engine. A Magnum, ASP, or any other engine in that matter.

I know this is not what you want to hear.[X(]

The above is excellent advice.

Wow, two clueless guys talking about engines they never owned.

It doesn't sound nice to the original poster who has the engine. If he likes his engine, then he got a great one regardless of what it is. That is all the counts in the end.

I dont think hobbsy was adressing the original poster

Ive seen, tuned & ran a MDS 48 recently. I was a very tight engine, but when tuned correctly it thrived on 0% nitro. true and cheap FAI fuel is all it needs to run well IMO.

Barry, I was obviously not referring to the original poster since I too have a MDS .48 and like it. If he listens to the sound advice given by the helpful posters he will like his too.

I have never seen or heard of any MDS set with different factory compression ratio for the US market. Possibly, if they had, they might still be in the US market? You might want to verify the source of that information. Sounds more like a WAG or wishfull thinking than fact. I have personally run the 1.48, .48, (2) .40s, and none of them was special anything for the US market. They are fine engines on their own merit. Like my others, the 2 .40s I have today run best on 5% nitro fuel containing at least some castor oil (Omega).

I might not have owned one , but as one of my clubs instructors I've lost count of the number of hours I, and the other instructors, have spent trying to get a consistent run out of these things. Some are good, most are bad.

You have probably dealt with perhaps 10 MDS's in your life . I've had to try and set up at least 30+ or more. Here in the UK these things sold like hot cakes, because they were cheap.

So if you have a good MDS that's great . BUT the fact remains that these engines were not consistant in their manufacturing quality. Why should you have to change O rings in the carb ? The thing should be fit for purpose out of the box. Would you buy a new car and then tear down the engine to get it to run correct.... of course not.

And as for being clueless........... Dave as a fellow member of club Laser , you should know me better than that !

Hi all,
First of all I did`nt think this was going to such a big topic, but it`s great to hear all of the advice i`m getting from some of you and I certainly won`t give up on the motor. I will try alot less nitro and give that a try and try some different plugs especially that fox one if I can find one, never seen or heard of one. But good news I won a new SC 46 ABC on ebay, so any advice on this whether it`s good, bad, or anything else, please let me know.

Many thanks again for all the advice, hope to hear from you all again.
Nige.

You damm right, I also have never owned one of the pieces of junk either. I too have far better things to spend my money on. Directed to the know it all person who thinks Fox plugs and fuel rule, and you know who you are. I have never tried to state that I am a no it all, like you do on an every day occasion.[sm=punching.gif][sm=punching.gif][sm=punching.gif]

Dave, I am not a know it all, I just happen to know what will work on that particular engine. I don't comment on engines I've had no experience with, now that's a know it all.