Boomstriker
Posts: 406
Joined: 1/15/2002
From: New Haven , MO,
Status: offline
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That's what I use to think HOMEBREWER-- till I bought a couple MDS's and learned the hard way.
I also assumed everything bad I heard about MDS was from guys that didn't have a clue or didn't have any engine experience. I've never had an engine I couldn't make run perfectly, but both MDS .58s I had as well as any I've seen at the field were nothing but trouble. Overheating, detonating and deadsticking was the norm.
Adding head shims or using 5% nitro helped, but power dropped to little better than that of a good .46.
If the manual says up to 15% nitro, then you should be able to run 15% without problems.
Mine wouldn't run on the plug it came with, the H9 that Horizon recommended, nor any A3, #8 or enya that works perfectly well in any good sport engine.
I know, I know. "The Fox idle bar is the cure-all plug". Well, just like the one it came with, it burned it in short order and was no improvement so I never bought another. Maybe, after a gallon of fuel it wasn't broke-in yet. I seem to remember the book saying a couple tanks. And if the Fox plug is so good for the MDS, why is it not recommended in the manual or by Horizon?
My observations were that the comp. ratio was way too high for 15% nitro and the carbs, both old and new versions, are way too rich in the midrange causing load-up and flame-outs. With 5% nitro, the power is disappointing at best and the transition is very slow.
Obviously, some of us have figured out the key and have gotten them to run better by following some simple rules, but if the instructions were to specify this and recommend no more than 5% nitro, supply extra shims, recommend a 1 gallon break-in and only a fox idle bar, maybe some of the others would have better luck getting them to run reliably.
I bought my .58s for 3D style of flying, which requires a reliable, powerful engine that will hold a needle setting, run consistently full to empty and in any attitude and have instant transition from any throttle. I can't have an engine that's going to flame-out in a 10' hover or be any less than 100% reliable.
Maybe if I flew straight and level 300' up at 3/4 throttle for a whole tank, or had it on a plane that collected more dust than bugs or wanted to raise my engine collection another count, I might be able to deal with all the DS and a cheap, under-powered MDS might fit the bill.
Most of us are in this hobby for fun. For me, it's not much fun if you constantly have to fiddle with a finicky engine that's not reliable.
Spending countless hours experimenting with different fuels, glowplugs, compression ratios, needle settings/tapers, tank levels, props etc. to get an engine to run reliably might be a huge 'sense of accomplishment' or even fun for a small percentage of guys with the time and patients.
The problem is, 99% of the guys that purchase an engine want, and expect it to run perfect right out of the box when they follow the instructions.
I'm glad some of you have also figured out the secrets to keeping an MDS running and are happy with them, but please don't further insult the majority of guys who regret their purchasing an |
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Horizon Hobby Dumps MDS Line? - 
RE: Horizon Hobby Dumps MDS Line? - 
