How to make an MDS 46 throttle.
11-02-2010 | 09:49 PM
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From: Dubbo, New South Wales, AUSTRALIA
How to make an MDS 46 throttle.
G'day engine folk.
Some time ago I wrote asking how to get an MDS 48 to throttle. (Actually it turned out to be a 46). Anyway, we have been flying it on a Kadet Senior with some success but it was always really rich in its mid range. Idle was perfect, throttle transition was good and the top end was fine but the midrange and in particular the lower part, was soggy.
Anyway, we kept at it but today its owner announced that he wanted to put it in an ARF Cessna and I decided it was just not reliable enough so I started looking in my small collection of carbys for one that might be better than the original. Most Asian carbys are too small by about 1mm so the ones I had were useless. That was until I remembered that I have a Super Tigre GS40 without a head but complete apart from that. Might this carby work?
In short - YES. It fitted perfectly and it runs fine. It needed a 1/8 turn leaner on the LSN and we have a perfect idle, perfect midrange and great top end. Throttling is good too. So into the Cessna it goes.
It is nice to win one occasionally.
Some time ago I wrote asking how to get an MDS 48 to throttle. (Actually it turned out to be a 46). Anyway, we have been flying it on a Kadet Senior with some success but it was always really rich in its mid range. Idle was perfect, throttle transition was good and the top end was fine but the midrange and in particular the lower part, was soggy.
Anyway, we kept at it but today its owner announced that he wanted to put it in an ARF Cessna and I decided it was just not reliable enough so I started looking in my small collection of carbys for one that might be better than the original. Most Asian carbys are too small by about 1mm so the ones I had were useless. That was until I remembered that I have a Super Tigre GS40 without a head but complete apart from that. Might this carby work?
In short - YES. It fitted perfectly and it runs fine. It needed a 1/8 turn leaner on the LSN and we have a perfect idle, perfect midrange and great top end. Throttling is good too. So into the Cessna it goes.
It is nice to win one occasionally.
11-03-2010 | 12:27 AM
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From: Everett,
WA
RE: How to make an MDS 46 throttle.
The Super Tiger is a fine carb. So there is little or no surprise that it worked.
The MDS carb is also a fine carb. If you have anylised it, I have to ask what was /is the problem with the MDS carb? They run surprisingly well on low or no nitro fuel.
This would be a great topic for my closed carb thread. Give it a read if you have time.
http://www.rcuniverse.com/forum/m_10015277/tm.htm
It is not clear why the moderator wanted it closed. I even said a few nice things about the OS 4B carb. It just doesn't add up.
All the best,
Konrad
The MDS carb is also a fine carb. If you have anylised it, I have to ask what was /is the problem with the MDS carb? They run surprisingly well on low or no nitro fuel.
This would be a great topic for my closed carb thread. Give it a read if you have time.
http://www.rcuniverse.com/forum/m_10015277/tm.htm
It is not clear why the moderator wanted it closed. I even said a few nice things about the OS 4B carb. It just doesn't add up.
All the best,
Konrad
11-03-2010 | 01:37 AM
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From: Dubbo, New South Wales, AUSTRALIA
RE: How to make an MDS 46 throttle.
G'day
I have no idea why the original carby did not work well. Probably because I don't know how to set it up. I tried all the usual things I know but if I leaned the bottom end enough to stop the over rich mid range it would not idle and accelerate.
It is the sweetest idling engine I have ever come across. It is also relatively quiet. The top end does seem a bit limited but I am not after power but rather reliability. Currently it is wearing an APC 11 x 6 and the fuel I used has 10% nitro, 5% castor, 15% Klotz 200 and 70% methanol. The engine has had very little use and has excellent compression and smooth bearings.
It is not my engine. A friend was given it by his brother who bought it some years ago. We put it in his Kadet Senior and managed to fly it several times but it was not nice to use although it never did stop. Kadets like to fly at about half throttle and if flown like this, the engine would gradually load up so that when some acceleration was asked for, it would splutter and cough until it managed to clear its self. It would then accelerate to full power.
The owner wanted to put it in an ARF Cessna but I would not have trusted it in its former tune. In the Kadet this really did not matter as Kadets really are gliders and are easy to handle if they dead stick.
Anyway, we are happy with the engine in its current form. It will do the job and appears to be reliable. And for scale models, that really is what matters.
Cheers
Mike in Oz
I have no idea why the original carby did not work well. Probably because I don't know how to set it up. I tried all the usual things I know but if I leaned the bottom end enough to stop the over rich mid range it would not idle and accelerate.
It is the sweetest idling engine I have ever come across. It is also relatively quiet. The top end does seem a bit limited but I am not after power but rather reliability. Currently it is wearing an APC 11 x 6 and the fuel I used has 10% nitro, 5% castor, 15% Klotz 200 and 70% methanol. The engine has had very little use and has excellent compression and smooth bearings.
It is not my engine. A friend was given it by his brother who bought it some years ago. We put it in his Kadet Senior and managed to fly it several times but it was not nice to use although it never did stop. Kadets like to fly at about half throttle and if flown like this, the engine would gradually load up so that when some acceleration was asked for, it would splutter and cough until it managed to clear its self. It would then accelerate to full power.
The owner wanted to put it in an ARF Cessna but I would not have trusted it in its former tune. In the Kadet this really did not matter as Kadets really are gliders and are easy to handle if they dead stick.
Anyway, we are happy with the engine in its current form. It will do the job and appears to be reliable. And for scale models, that really is what matters.
Cheers
Mike in Oz
