1/2A

[bob werle]

I am trying to build some 1/2A planes,control line of course, but I am having problems with my old  Cox motors.  These are the old golden bee motors with the brass reed.  No matter where I set the needle valve the motor runs verrrry rich.  Does anyone have Any ideas?  I want to start my grandson on the 1/2A size Blackhawk kits. 

[dankar]

Davis Diesel sells mylar reeds. Yahoo groups has a 1/2A forum and they are very helpful. Reed valve engines needs a very good cleaning and reed needs to be good. Tank clean/ needle clean/ fuel pickup line in good shape. Any dirt or fuel residue and trouble. Low sport fuel is a problem. Drug stores carry 91% alcohol that cuts most of the slime. Castor in fuel is a must.
Dan

[minnesotamodeler]

Pull the needle valve and check the business end--it's supposed to come to a very sharp point, but I've had more than one on which the point has broken off, leaving it somewhat blunt and impossible to lean out enough. One of mine developed the opposite problem (too lean to run); and I found the needle tip stuck in the orifice. They're apparently pretty fragile.

 I don't know of any fix other than a replacement needle.  You can buy a whole replacement engine for $8 still, I think (Cox Production "sure-start" or something like that). 

[Garf]

This is usually a failure of the o-ring between the tank and the tank back. It's so small most people overlook it, but it's important.

[Alan Hahn]

I think Phil hit the nail on the head. 
You can substitute a thin slice of small fuel tubing for the gasket if you don't have one.

[Larry Renger]

Gee whiz, Bob!  You have me, Dale Kirn and Randy Heydon in your club!  What isn't known about C*x engines between the three of us isn't worth knowing.  Talk to us!   

[Robert McHam]

Agreed. The trouble sounds exactly like the o-ring seal between tank and the backplate.

A tip I learned to make cutting that tiny o-ring from the fuel tubing is to slip a round toothpick into the fuel line before you try to cut it.

Robert 

[kenneth cook]

        I recently had a bit of a problem with freshening up a golden bee I had. The newer stainless was too thick to fit under the circlip. I own one white I believe this is the mylar reed and it was too thick. I could still install the circlip but the reed wasn't able to move freely. I'm well aware of the fact the circlip can only be installed one way. I pulled another golden bee apart only to discover the same thing. Both of these engines had the copper style cross reed. I don't have a micrometer to check, but its noticeable by eye the difference in thickness. I happened to have a black widow tank on the table and all the reeds I have work freely under its circlip. Ken Cook

[bob werle]

Thanks for your advice.  I did find one kinked fuel pick up line and a missing o-ring.  This is the first time I have used this type of forum and I thank all of you who responded.

[kenneth cook]

         I insisted on using the white reed I had. I got the circlip on and the reed was snug but free enough to work. I put the engine on the plane and was off . Well, the engine started and it was off on a good run. It landed I refueled and leaned it up a bit when something bad happened. The circlip popped out. After I install them, I make it a habit to rotate it so that I know its engaged in the groove. The engine made some horrible noises. This so happened to be one of my best running engines. Initially I that the glow plug launched leaving the piston to grind the element in the cylinder. When I approached the plane the metal dust was coming out of the ports. I never had this happen ever. I've run these engines a thousand times. I cleaned it up and put it on the shelf. One more gift to the gods of flight. Ken Cook

[Larry Renger]

If I recall correctly, the stainless reed is no thicker than the original phosphor-bronze ones.  However it is really easy to not separate a couple or even three of them and install them as one.  Use a solvent and magnifier to be sure you only have one reed to install!  The oil bonding the layers together is pretty thick and congeals with time, and the reeds are only .0015" thick, so several look like one.

Having worked on the development of them, they are the best we could devise.  And be sure we had all the historical ones to check out!  I personally have never been able to make the teflon reeds work well at all, and the Mylar ones are superb at first, but warp with heat and have no durability.