Why would I not want to buy an MDS engine?
They are so much cheaper than everything else and a guy i know says that they are no different or unreliable than anything else he has ever used.
So why not?

I had a 40 2 stroke on my trainer and even with an experienced pilot he couldn't get it to stop dead sticking, after about 10 tanks of fuel through it I never had a dead stick again, I liked it! Unfortunatly you get what you pay for too, they don't have the power that a lot of the other motors have. Buy an OS and you will not be unhappy! I'm guessing you have a trainer type airplane so the 40 or 46 fx will do you nicely and you can take it off the trainer later and put it on you second or third airplane...just buy the 46 fx 100 even

Ive run into a couple that were pretty good and a couple that were not. I have heard they had a run or two of bad carbs.

I got my 5th MDS a couple of months back, it's a .48, I thought it was going to be problematic at first but I put a Fox idle bar plug in it and instantly have a great running engine. And to answer your question, nothing.

NOTHING at all other than user headspace and timing problems.

Wow! a new record! 3 hours and 14 minutes till the personal insults begin on this topic!

Spiff, you sure are thin skinned dude.

I have two new ones that were given to me. not even the LHS owner could get them to run right, the previous owner is so up set at MDS products that he doesn't even want to go thru the trouble of sending them back for replacement or repair.
I tried another carb (K&B) and it ran better, not much of an idle.
It looks like the machining is great do.

My 2cents

Some common problems are caused because-

They need low nitro fuel...

Most of them need a cold plug...

They need a very long break-in, probably a gallon before they really start running good. Adjusting them before this and trying to lean them out is a big mistake. Just "running a couple tanks through" is not a proper break-in.

Broken-in right with the right fuel, plug, prop, and mixture, most of them have more power than most of the other engine in their class.

There is nothing wrong with most of them. There were some bad carbs and bad mufflers, but those problems are and have been resolved.

Another problem with them was that they came with instructions that were completely wrong for them. They recommended 15% fuel, the wrong plugs, and the wrong break-in technique. The engines come from...uhh...can't remember. Russia? All I remember is that the instructions were written by a completely different manufacturer here in the U.S. for them and they were wrong...

Anybody else have any clue what I'm talking about?

Hi all!!
Yes, BotleRocketWar. THe instructions doesnt seem to be right at all..

I just gave up with my MDS .48.. I´ll never start it again. It sucks!! Tried everything to get it working. It works fine sometimes, but suddeny stops or needs readjustments.. I hate it!!

Bought me an OS 50, the ringed one. Its a dream!!!!!
Buy a better engine than the MDS. Before you broked it in and bought a whole set of plugs, its became a lot more expensive then a OS. Its true, I know!!
And you dont has to crash your fine plane because of an engine that stops everytime you fly with it..

Buy an engine. Not an MDS!!!
-j

Must add...
There is not much power in the MDS .48 either.. it weak!

You're wrong about the power, my .48 turns a 12x5 Graupner at 12,500 rpm and on Fox 5% fuel and a Fox idle bar plug is totally reliable.

I have an older MDS 46 Black Head I was told by the guys in my club I could never get to run right. I bought it on e-bay not knowing much about engines at the time. This engine seems to be a solid build engine so I was determined to figure out what was wrong with it. When I first got it it would no idle at all and just quit running for no reason. I did a search on the wed for this engine and found an article that someone wrote on MDS carb problems. It seems the early engine suck alot of air where the carb fits into the case and at the gad nibble on the carb. I went and got some red RCV silicone from auto zone to seal there trouble spot. The article also said you should have the idle bar type glow plus. After doing this and going to 10% fuel the engine runs and idles great. It is not a speed demon so I use it on my 1/6 scale Piper Cub I built.

I hope this helps

[QUOTE]Originally posted by BotleRocketWar
[B]Some common problems are caused because-

. Just "running a couple tanks through" is not a proper break-in.

Broken-in right with the right fuel, plug, prop, and mixture, most of them have more power than most of the other engine in their class.[QUOTE]


I have to agree with Botlerocketwar--I have 3 MDS engines, and they are fine.(two of the "infamous" 1.48's, and a .78)

They MUST be broken in properly! No big deal, and you actually learn more about an engine when you do a "Bench" break-in. IMHO.


Really do love mine---'kinda nice to pick 'em up so cheap from guys who don't like them!
Pud

Guys I always try to stay Neutral on the issues of inexpensive (cheep) engines but, on behalf of instructors everywhere I need
to make a comment (or request) HAVE A LITTLE PITY ON US it's one thing if you are an engine expert and don't mine "TINKERING" OR WASTING time figuring out why or how the engine MFG did not do his job in the QC dept, by all means Tinker away ,but if your new to engines buy quality and give your club members a break.

When a student show up at our field with a good Quality engine like OS (and a few others)we all fight over who's gets to train him, because we know we will actually get to teach FLYING, not how to dead stick his plane 20 times or spend hours(SOMETIMES DAYS) trying to fix a problem, only to send him home with a list of possibles FIXES...." change lines, get new Oring, seal up carb,backplate, New Carb , change muffler pressure , get pump, or the hundreds of other possible modification needed to make the BARGAIN ENGINE RUN RIGHT.

Do yourself a favor and Don't scrimp on the engine and enjoy what you came to the field for FLYING. Tinkering can come later when you are bored and have the time to entertain yourself

Just my .02 worth

I have gleaned enough info from this forum now and have gone out and purchased an OS isntead of the MDS.
I figure the few extra dollars is worth the peice of mind anyways.
I am not much for tinkering so this was a better dicision I think.
Thanks to everybody for all of your input.'
Lean540

Amen Brother Checklst!

If a cheap engine ruins a good saturday, is it still cheap? absolutley not!

I don't want to get into a war over this, but I believe the original question was "whats wrong with MDS" not whats right with OS. I know OS is a great engine I even own one. But it is by far not my best engine. I own a OS 46 FX and it is very reliable and runs great. But I also own MDS, Magnum and Tiger Shark engines. I have had to work on all of these engines at one time or another so asking a question on whats wrong with MDS makes good since to a person who is thinking about trying another engine. Do not be afraid of trying something different. I didn't and found out my Tiger Shark 46 & 52 are every bit as good as an OS and at 2/3 of the cost.

Have a ball with your MDS if you decide to go that direction.

Thanks

After reading all I could about the MDS engine line here over the past two months.....it seems about 1/2 the group hates MDS, and 1/2 likes MDS. I was cautious before I finally decided to buy one (from a guy on rcuniverse in fact). Having run the engine (MDS 58) now, I can now add my 2 cents worth.

It runs like a champ! Top end, idle, transition.....all passed with flying colors. Adjusting the needle was a snap (no tinkering) So.....I don't know why people are having trouble with MDS.....I'm not. Good luck!!!!!

The good thing about this hobby is that you have so many choices. Some guys spend big, others not so big....................
Its interesting just watching..................

Spend a little time researching and shopping around and you'll have a model/engine that performs (sometimes better) and with the reliability of the big name brands at 50% of the cost.

I bought an SC .75 for my sons 4*60 (got plenty of shock and horror from other club members). I "wasted" a bit of time on the engine to get it to run right and guess what, its now the best performing glow engine I have, at a 1/3rd of the price of an equivalently rated name brand.

Nothing wrong with the cheapies, if your willing to spend a little time and listen to the guys who KNOW.

Cheers
Ossie

A couple of years ago, a new guy showed up with a MDS 46. He had the plane RTF. He was told to just fly the engine as is-- no break-in.

It sounded OK on the ground, but would dead stick after about 3 minutes. It did this for each of 3 flights. He was visibly disappointed with his first RC experience.

I went over to him to give my opinion about break-in( he was told that bench running / break-in was foolish) I suggested some more time running in and offered to help. I didn't see him again for about a year.

He shows up at the club field and ask me for help. He did run the engine at home after that first day-- he later told me. It did fine. A very consistent needle for the whole flight. We flew all day with no problems. I just think it needed a longer break-in than some other engine types. It had none of the leaking o-rings, bad carb or compression issues that we see so many of on the newsgroups.

I prefer the bench for all of my engines because you control its environment. Tank position is terrible in some airplanes-- especially for the newbies that are still learning. You can check to makes sure there is no foaming, air bubbles and have access to everything. I even suggest using a different fuel tank if you are trying to trouble shoot a problem. If it runs good on the bench, accept nothing less in the plane.

I have seen several MDS that ran just fine without all the extra time. That one just needed some TLC initially. I even have a soft spot for the MDS 68 after seeing a few-- very impressive engine of any make.

turbo