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MDS .78 RPM #'s w/MAS props

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Old 09-19-2009, 01:22 PM
  #1
rsieminski
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Default MDS .78 RPM #'s w/MAS props

MDS .78
Stock silencer, no baffle
2.5%/20%(50/50) Homebrew
.004" shim, Fireball STD idlebar Plug
13x6 MA K 10.5K
14x6 MA K 9K
15x8 MA K 7K

Idle is easily 2600, with the 15x8 I could get 2000, but would set it to fly at 2600, because of the vibration, perfect transition.

I wish I could get the 10k people have reported with the 14x6! I removed the baffle for these numbers, improved transition, and increased WOT rpm by about 200.
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Old 09-19-2009, 02:10 PM
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Default RE: MDS .78 RPM #'s w/MAS props

HI

I have a .68 but not run yet...

How long have you run the engine? the engine is ringed so it may take a while to get where you want to...so take it easy and run it slower until you get more time with it.

Have you tried a plug without the idle bar? maybe a hotter plug?
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Old 09-20-2009, 10:55 AM
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Default RE: MDS .78 RPM #'s w/MAS props

I tried a Fireball Hot non idle bar plug, and the rich midrange blew it out. I have at least 1.5hrs on it. It is surprisingly tame, the needle has a lot of range on it, but the true test will have to be in the air.
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Old 09-20-2009, 11:06 AM
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Default RE: MDS .78 RPM #'s w/MAS props

A rich setting does not burn plugs! Burn plugs are caused by too much nitro (not the case) or prolonged lean runs (not the case nether?).... what I think is that maybe your engine had maybe metal shaves prior to running in (which is very common with mds...I had to clean my 48 because it had shaves everywhere), or while running in, very thin metal powder was produced (what makes the exhaust oil black during running in) and any of the two possibilities fouled the plug! I would try a normal plug again.

Do you have the C2 carb?

saludos,

Jorge
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Old 09-20-2009, 02:49 PM
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Default RE: MDS .78 RPM #'s w/MAS props

I think you must have misread my post. "the rich midrange blew it out", using a metaphor here. "Blew it out" like a candle. The rich midrange(common with this engine) splashed the plug and stalled it, every time. The plug did not foul, it's still good. Sorry for not being clear. You are right, all engines have the little metal shavings left over from machining the parts. MDS has a rep for having a lot of flash left, and this one was no exception. I could not believe how much stuff came out of there. I learned a long time ago, that you need to thoroughly disassemble and wash out the engine parts, and reseal them with high temp RTV. So that was already done. A new engine will always produce the black gunk due to the microscopic Al particles oxidizing. When they oxidize they turn black. Many times the muffler will cause it from not being tight enough. That's what always happens to my Tower/GMS mufflers.
Yes I have the C2 carb, as well as a few of the other ones. I may try the original one, or maybe I should be happy with the numbers that I got? I've got it tuned pretty good now. I'll find an airframe to put it in and run some more fuel through it, and try to clean the goo off of all the flowers in the yard, left by the rich run in.
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Old 09-20-2009, 03:03 PM
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Default RE: MDS .78 RPM #'s w/MAS props

Then I think I understand!!

The ringed engines take much time to settle...expect it to take about 2 gallons to see the real engine....but now it sounds good I think. Your rich midrange may be improve with more run time.

Now I have 3 MDS engines, a 48, a 68 and a 148...the first two bought them for 40 Euros each, the 148 for 84 Euros... I ordered a ASP carb for the 148 since it comes with the C1 carb, the others have C2 carbs.

I like them very much, look great, and are well done, with some misses but nothing critical. Unfortunately I haven't run them, they are in box waiting for a home

The 48 had too much shards, the others didn't have any...but the 148 seemed to be sitting on the shop for a long time and was dry and the cylinder began to rust, I just wipped it and it is ok.

Now I dissassemble every engine that comes to me...I just can't help myself...I just like to see those shining guts =)

I would also try a 12x7-8 and see what happens. And also try some Master S2...I like them very much.


By the way, very nice pictures out there!
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