Notices
Glow Engines Discuss RC glow engines

Do all MDS engines run this HOT.

Old 05-21-2008, 06:40 PM
  #1  
iflyg450
Thread Starter
 
Join Date: Jul 2006
Location: townsend, GA
Posts: 927
Likes: 0
Received 0 Likes on 0 Posts
Default Do all MDS engines run this HOT.

I was brakeing in a MDS .18pro on my stand. Running 10% omega and the recomended brake in prop and a mediume heat plug. One thing I noticed with this engine, the point of sloopy stalling rich and melt down lean is only two or three clicks! It ran in very well after shutdown it was very hot. My dad runs a MDS .61 he agreed with me that it does seem to be a very hot engine. Does anyone else agree or disagree???
Old 05-21-2008, 06:51 PM
  #2  
Rcpilot
My Feedback: (78)
 
Join Date: Mar 2002
Posts: 7,790
Received 6 Likes on 5 Posts
Default RE: Do all MDS engines run this HOT.

I've never had that same motor, but I've had 2 of the 148. I had a 2.18 and Also had 2 of the .68. I know a little about MDS engines. Just a little.

Check for air leaks around the needle and where the carb seats into the crankcase. MDS engines are notorious for leaking carbs, especially around the O-ring on the carb throat. Sometimes the O-ring isn't big enough to make the seal perfect.

The reason why it goes from sloppy rich to too lean is because it's sucking air all the time. There's no way to meter the fuel correctly when the case or carb is leaking air. You have to seal it up. Check the head. Check the backplate. I'll bet it's the carb though. Either the needle or the carb throat.

Once you get it sealed up, it will be a lot more forgiving on the needle. As long as it's sucking air, you'll never get it to tune correctly until you find the leak and seal it up. Use RTV silicone or a bigger O-ring. Clean all the oil off first or it will stick about as well as snot on a diving board.
Old 05-21-2008, 07:29 PM
  #3  
iflyg450
Thread Starter
 
Join Date: Jul 2006
Location: townsend, GA
Posts: 927
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Do all MDS engines run this HOT.

That makes sense Will have a look at that tonight. This is my first time messing with an MDS, and for the price it seems to be a very powerfull motor. It is going on a SIG Wonder
Old 05-21-2008, 09:41 PM
  #4  
Hobbsy
My Feedback: (102)
 
Hobbsy's Avatar
 
Join Date: Dec 2001
Location: Colonial Beach, VA
Posts: 20,370
Likes: 0
Received 20 Likes on 20 Posts
Default RE: Do all MDS engines run this HOT.

IF, how much lube is in the Omega, 20% castor would make it run considerably cooler. 0% or 5% nitro is the order of the day for MDS engines.
Old 05-21-2008, 11:07 PM
  #5  
Rcpilot
My Feedback: (78)
 
Join Date: Mar 2002
Posts: 7,790
Received 6 Likes on 5 Posts
Default RE: Do all MDS engines run this HOT.

Omega is 17% oil. It's 70% synthetic and 30% castor. I use 5% in all my glow engines. Works just fine and it's the cheapest fuel I can get. Been using it for a lot of years.

Hobbsy is right about the nitro. The MDS was built and designed in a country where nitro is quite expensive. 5% is plenty unless you start competing for money or nekkid beauties.
Old 05-21-2008, 11:56 PM
  #6  
iflyg450
Thread Starter
 
Join Date: Jul 2006
Location: townsend, GA
Posts: 927
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Do all MDS engines run this HOT.

The lowest I can get is 10% will that be okay?
Old 05-22-2008, 12:19 AM
  #7  
greggles47
 
Join Date: Jul 2006
Location: Sydney, AUSTRALIA
Posts: 529
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Do all MDS engines run this HOT.

I've got an MDS15 Control line motor. It was designed for 4:1 fuel that is 80% methanol 20 % castor oil. (I can't believe there is any fuel cheaper than that!) You should hear that baby come up on pipe!!!! Woohoo!

!0 % nitro certainly isn't going to hurt your motor - but be sure to flush it out at the end of each days flying. If you must use the fuel you mention add at least 5 % castor.

The lack of lubrication (caused by using synth oil) could be causing the overheating. If nothing else you're not going to do any damage by adding oil, as opposed to having too little.

Regards

Greg
Old 05-22-2008, 02:47 AM
  #8  
XJet
Banned
 
Join Date: Mar 2003
Location: Tokoroa, , NEW ZEALAND
Posts: 3,848
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Do all MDS engines run this HOT.


ORIGINAL: greggles47
!0 % nitro certainly isn't going to hurt your motor - but be sure to flush it out at the end of each days flying. If you must use the fuel you mention add at least 5 % castor.
I beg to disagree.

An engine that's designed for 0% nitro may well suffer from detonation if run with 10% nitro, especially if a pipe is used.

My MDS 61 came with an extra two head shims that were included to allow use on higher-nitro fuels. I wouldn't run it with anything more than 5% nitro on one shim and even then I detected some detonation with props at the larger end of the acceptable range.

Old 05-22-2008, 01:32 PM
  #9  
RCVFR
Senior Member
My Feedback: (7)
 
Join Date: Feb 2002
Location: Keller, TX
Posts: 2,050
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Do all MDS engines run this HOT.


ORIGINAL: iflyg450

The lowest I can get is 10% will that be okay?
If 10% is all you can get, then get another engine that likes 10%. The MDS engines I have run (2 - .40s, a .48 and a 1.48) all did well on 5% or FAI but did not like higher nitro.
Old 05-22-2008, 02:01 PM
  #10  
Sport_Pilot
 
Sport_Pilot's Avatar
 
Join Date: Jan 2002
Location: Acworth, GA
Posts: 16,916
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Do all MDS engines run this HOT.

Anybody can get 5 or 0%. The first place I'd start is to ask the LHS to buy me a case. If not it can be ordered. 0% is only oil and fuel, so buy them and mix them.
Old 05-22-2008, 04:44 PM
  #11  
iflyg450
Thread Starter
 
Join Date: Jul 2006
Location: townsend, GA
Posts: 927
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Do all MDS engines run this HOT.

The manule says 5-15% nitro recomended. I think the hot engine is a result of the air leaks I fould aroung the carb and needle
Old 05-22-2008, 05:49 PM
  #12  
Rcpilot
My Feedback: (78)
 
Join Date: Mar 2002
Posts: 7,790
Received 6 Likes on 5 Posts
Default RE: Do all MDS engines run this HOT.


ORIGINAL: iflyg450

The manule says 5-15% nitro recomended. I think the hot engine is a result of the air leaks I fould aroung the carb and needle
So you found air leaks?

10% is fine man. Put a head shim or two in it and fly it. It was the air leaks that was causing it to run lean and get hot. Don't worry about it. Maybe use a cooler plug too.

Honestly, if it was me and all I had was 10%, I'd fly it. If it runs then don't worry about it. If it detonates and starts cackling put 2 head shims in and use a cold plug. No big deal.
Old 05-22-2008, 06:14 PM
  #13  
Hobbsy
My Feedback: (102)
 
Hobbsy's Avatar
 
Join Date: Dec 2001
Location: Colonial Beach, VA
Posts: 20,370
Likes: 0
Received 20 Likes on 20 Posts
Default RE: Do all MDS engines run this HOT.

Horizon probably wrote those manual recommendations for 5 to 15% but failed to tell the engine.
Old 05-22-2008, 07:37 PM
  #14  
rcdude7
Senior Member
My Feedback: (264)
 
Join Date: Apr 2003
Location: Great Mills, MD
Posts: 2,223
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Do all MDS engines run this HOT.


ORIGINAL: Hobbsy

Horizon probably wrote those manual recommendations for 5 to 15% but failed to tell the engine.
Yes, the engine did'nt get the memo from horizon

Mine seem to run okay on 5% omega with a hot plug. I have to request a case of 5% when the glow fuel is ordered by my LHS. They sell mostly 15% to their cutomers.
Old 05-22-2008, 07:53 PM
  #15  
Jezmo
Senior Member
 
Jezmo's Avatar
 
Join Date: Jun 2006
Location: Spring, TX
Posts: 2,132
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Do all MDS engines run this HOT.

Had a 48 for about a year that didn't mind 15% at all. Ran great, and no dead sticks but the carb was a little more sensitive on the idle mixture than some but once I got it dialed in I never had to mess with it again. Still had very good pinch when I traded it and the plane it was on for something different.
Old 05-23-2008, 07:25 AM
  #16  
Hobbsy
My Feedback: (102)
 
Hobbsy's Avatar
 
Join Date: Dec 2001
Location: Colonial Beach, VA
Posts: 20,370
Likes: 0
Received 20 Likes on 20 Posts
Default RE: Do all MDS engines run this HOT.

I still have a .48 and found the secret to excellent running was an ordinary Fox idle bar plug and 5% fuel with 20% castor. All the MDS engines have some serious compression after about 30 minutes run in time. The ABC ones have it from the git go.
Old 05-23-2008, 09:09 AM
  #17  
jaka
 
Join Date: Dec 2001
Location: Upplands Vasby, SWEDEN
Posts: 7,816
Likes: 0
Received 1 Like on 1 Post
Default RE: Do all MDS engines run this HOT.

Hi!
It's very simple! If an engine is very finicky on the high speed needle and suddenly stops when you try to adjust for max rpm ...you use too much nitro! It's that easy!

And the fix is as easy!
All you do is put in another 0,1mm head shim ...or run less nitro! In this case 5% max! What do you prefere?
Old 05-23-2008, 09:41 AM
  #18  
Sport_Pilot
 
Sport_Pilot's Avatar
 
Join Date: Jan 2002
Location: Acworth, GA
Posts: 16,916
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Do all MDS engines run this HOT.

The manule says 5-15% nitro recomended.
My ASP .91 Redhead manual says it runs on 15% also. It won't even during the winter. I can run 10% in the winter, 5% on all but the hottest days. Sometimes manuals say what they think you want to hear.
Old 05-23-2008, 10:06 AM
  #19  
Hobbsy
My Feedback: (102)
 
Hobbsy's Avatar
 
Join Date: Dec 2001
Location: Colonial Beach, VA
Posts: 20,370
Likes: 0
Received 20 Likes on 20 Posts
Default RE: Do all MDS engines run this HOT.

Hugh, I have the Red Head 1.08, a gift from w8ye, and it rattles a little on 5% fuel. I still entertain the idea of converting it to Diesel. It is an excellent engine.
Old 05-23-2008, 03:29 PM
  #20  
Sport_Pilot
 
Sport_Pilot's Avatar
 
Join Date: Jan 2002
Location: Acworth, GA
Posts: 16,916
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Do all MDS engines run this HOT.

Well more displacement or at least bore will also increase the possiblility of detonation. Though it could also have more compression.
Old 05-26-2008, 01:52 PM
  #21  
2HI2C
Senior Member
 
Join Date: Mar 2006
Location: Burlington, OK
Posts: 575
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Do all MDS engines run this HOT.

I run my MDS 2.18 on 5% & 10% & runs fine on both.
Attached Thumbnails Click image for larger version

Name:	Xv64134.jpg
Views:	12
Size:	53.5 KB
ID:	957291  
Old 05-26-2008, 03:23 PM
  #22  
LeeHop
Senior Member
 
LeeHop's Avatar
 
Join Date: Apr 2005
Location: Aurora, OR
Posts: 248
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Do all MDS engines run this HOT.

2HI2C - that's a nice looking installation.

What are the pink bits at the fuel line connections?

Tnx - LeeHop
Old 05-26-2008, 10:06 PM
  #23  
2HI2C
Senior Member
 
Join Date: Mar 2006
Location: Burlington, OK
Posts: 575
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Do all MDS engines run this HOT.

Thanks, Those are high temp heat shrink tubing. It helps keep fuel lines tight & from getting air leaks.

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright 2021 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.