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TD .049 and TD .90 engines

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TD .049 and TD .90 engines

Old 04-06-2016, 01:38 AM
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tewitt1949
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Default TD .049 and TD .90 engines

I was quite active using both engines 4-5 years ago but got involved in bigger stuff so these little engines have been setting on the shelf. Seems like the last time I used them I was having a terrible time keeping them running. This was going on for a month or so. They would run good holding them, but after I'd launch them, they would run like crap or quit. I've used them for years so I'm familiar with these engines as far as carb cleaning etc.

I was using fuel about 15% nitro with castor. Is it possible the 15% was the problem? I had a friend give me some 30% heli fuel. Think that would help? What percent nitro do you guys use?

I just read the post below "
[h=3]Request For Tee Dee Help[/h] Answered many questions I had.

Last edited by tewitt1949; 04-06-2016 at 02:05 AM.
Old 04-06-2016, 07:22 AM
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20% all castor 25 to 35% nitro
Old 04-06-2016, 04:35 PM
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I wish cox made a TD .90, that would be fun
Old 04-06-2016, 06:06 PM
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tewitt1949
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Maybe I'm wrong and I probably am but, I thought they did make a TD .90.

Edit.......Sorry TD.09

Last edited by tewitt1949; 04-06-2016 at 06:26 PM.
Old 04-06-2016, 06:21 PM
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Td .09.
Old 04-06-2016, 06:22 PM
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Pond Skipper
 
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No a TD .09 almost a .10 size engine now times that by 9. Would be around 1,200g or 42.2oz or 2.64 Lb. engine around 2.4 Hp.
Old 04-06-2016, 06:35 PM
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There were TD .010, .020, .049, .09 and .15. They ran best on high nitro.....above 25% but there were fuels with higher nitro. I always used Missile Mist. It may have been 40% nitro. Someone will know. But would not be able to afford that now

bob
Old 04-06-2016, 06:54 PM
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MJD
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Lots of cool and interesting Cox info here: http://www.mh-aerotools.de/airfoils/cox_frameset.htm
Old 04-06-2016, 06:56 PM
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40% is rather expensive, but the motors are pretty small, and a quart will last a season. Your car will spend more to drive it to the field. Maybe the problems the OP is having are from unfiltered fuel. The three holes in the venturi are pretty small, and get plugged easily. Could be overheating, getting lean at the end of the tank if it is a largish tank, varnish in the cylinder, low oil content, or air leaks.....
Old 04-06-2016, 07:49 PM
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Originally Posted by MJD View Post
Lots of cool and interesting Cox info here: http://www.mh-aerotools.de/airfoils/cox_frameset.htm
Very interesting thread.
I just looked through the 30 or so photos on that site - what history. I had never seen those historical photos before, and it is an interesting look in on production of these engines with the personalities involved.

Keep those engines running!
Old 04-07-2016, 05:04 PM
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049flyer
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I've had excellent service from all of my Cox engines, TD s included. If you can't make them run there is a reason for it. My bet would be a tiny crack in the plastic front housing. I inspect them under strong magnification and an equally strong light. It's amazing what trouble the smallest defect can cause.
Old 04-07-2016, 08:57 PM
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I run TD .049s often with 10 to 15% nitro and the performance is good.
The bonus is improved run times and glow plug life.
Old 04-08-2016, 05:36 AM
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Although I prefer replacing the carb bodies if cracked, I have made very effective and lasting TD repairs by binding together the threaded collar with kevlar thread and epoxy (regular works, I just happen to have a spool of Kevlar), while the venturi is inserted to make sure it is on size.

I agree with CP on fuel, though I don't use 10% - .049's are quite happy on 15%. PW .020's are okay but needle better on 25%. .010's - not applicable.
Old 04-08-2016, 05:52 AM
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Originally Posted by TampaRC View Post
I wish cox made a TD .90, that would be fun
About a large Babe-Bee
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Old 04-08-2016, 05:59 AM
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In the last three years I have been running 25 / 30 and 35% so far no burnt out plugs. 1 CL and 5 RC planes.
You can use a brass tube collar over the cracked carb body too, wick in some CA in the crack and then bind
with a tight fit collar will keep things going till you replace.
Old 04-08-2016, 06:00 AM
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I wonder if he ever ran the Baby Bee would be loud for sure lol.
Old 04-08-2016, 07:46 AM
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I like 25% as a general
Old 04-08-2016, 10:54 AM
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Originally Posted by coriolan View Post
About a large Babe-Bee
I've seen that pic but dunno where - is it a runner? My rough screen measurement shows it is about 3X scale, jeez must be 1.2 - 1.4 cu in.
Old 04-08-2016, 11:29 AM
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Lol what about hand scale to engine?

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Old 04-08-2016, 12:57 PM
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http://www.microsofttranslator.com/b...128-Coxmotoren
Old 04-08-2016, 03:37 PM
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Per owner Burki:

Cox BabyBee
0.8 ccm

That one is 23.3 ccm
1200g
Fuel tank capacity is approximately 125 cc.
Bench tested and started right up
Says he wants to build two more at the time 2010
1/4 "-32 thread to use a glow plug



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