.049 Medallion from EBay

Ivanhoe Tue Nov 15, 2011 11:49 am

(on eBay)[SOLD] Cox Medillion .049 $18.99 BUY IT NOW!
Admin on Fri Oct 28, 2011 5:55 am
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-http://www.ebay.com/itm/COX-049-TEE-DEE-/310354870175?pt=Radio_Control_Parts_Accessories&hash=item4842977f9f

Not too bad if you don't have one yet! .

Remember this one, folks? I bought it after seeing it mentioned in Buy & Sell here. Well, it arrived today, basically in very nice condition, just a little discolouration of the red plastic crankcase, and a missing spinner, which had been replaced by a double-ended shaft which I think was the thing that the rubber spinners used to use. I locked two nuts on it to remove it and the engine now has it's proper spinner.
It was a little stiff, but new fuel soon sorted that, and it runs OK but a bit roughly, it's doing what we used to call "Hunting" sort of speed up, slow down, repeatedly. I think the problem is needle/spraybar, in my rush to play with the new toy I admit that I didn't check or clean those, and I have an idea that the spraybar hole may not be positioned properly, I will remove them and have a look tomorrow.

Thanks to Admin for putting it up, and any suggestions to sort the running out would be welcome

Wilf

nitroairplane Tue Nov 15, 2011 12:31 pm

I know this problem, I have encountered it countless times with diesels usually means the compression or NV is about right but not quite there so maybe play around with head gaskets and just run it until the problem goes.
What fuel are you using?
This can happen when running engines without sufficient lubrication.

Ivanhoe Tue Nov 15, 2011 12:51 pm

nitroairplane wrote:I know this problem, I have encountered it countless times with diesels usually means the compression or NV is about right but not quite there so maybe play around with head gaskets and just run it until the problem goes.
What fuel are you using?
This can happen when running engines without sufficient lubrication.

Your mention of compression gave me a thought, does the Medallion use the same head as the Babe Bee? The head that came with it was burned out, and I was running it with a standard Babe Bee head, would that make a difference?

Wilf

nitroairplane Tue Nov 15, 2011 12:55 pm

They came with normal cox heads e.g. the babe bee head.
Did you make sure it had a Gasket?

dankar04 Tue Nov 15, 2011 1:21 pm

I bought an .049 Medallion but paid way to much for it . I have a project fir ir so no real loss as not that common an engine.
Dan

Ivanhoe Tue Nov 15, 2011 1:52 pm

nitroairplane wrote:They came with normal cox heads e.g. the babe bee head.
Did you make sure it had a Gasket?

Good, thanks for that, I left the original gasket in place, I suppose it could be flattened, I'll put a new one in before I try it again.

Wilf

nitroairplane Tue Nov 15, 2011 1:56 pm

Also do you run model technics GX 25?

PV Pilot Tue Nov 15, 2011 2:19 pm

The hunting can be caused by different things. One you touched on was the dirty needle. you get a bit of "green" on that metered area, and the engine runs down to where the mix is idle right, then slowly picks up rpms,,then runs into the green fuel block and limits that out,,back down go the rpms.

A worn out piston and sleeve will do that also.. it will hunt when cold, but once it warms up it runs fine usually.

A motor with a compression leak will/can do it as well.

A glow plug that is about to pop or is weak.

Moisture in the fuel.

Ivanhoe Tue Nov 15, 2011 3:07 pm

Thanks to everyone for their useful advice, I will bear it all in mind before re-trying the Medallion.

Virtually all of my previous long experience with engines was almost entirely with diesels, back in the 50s & 60s glows never really took off in England and after a break of around 40 years I am having to learn a lot of skills regarding small glows, which is why I am grateful that there are people here willing to give help and advice freely when needed.

Thanks folks!

Wilf

nitroairplane Tue Nov 15, 2011 3:12 pm

Wilf a few British companies did make small glow like DC of the Isle of White I have a DC wasp that it a little glow engine but is built a lot like a diesel and doesnt run too well.
Did you ever own a DC Bambi?
I wish i did Sad

Ivanhoe Tue Nov 15, 2011 5:03 pm

nitroairplane wrote:Wilf a few British companies did make small glow like DC of the Isle of White I have a DC wasp that it a little glow engine but is built a lot like a diesel and doesnt run too well.
Did you ever own a DC Bambi?
I wish i did

Yes, I had a Bambi and also a Frog 50, the only two engines I could never get to run! I gave both of them away, by 'eck I wish I had them now, seeing the ridiculous prices collectors pay for them! I have an old advert for the Frog 80 diesel when it was first produced, price new 45/- (£2.25) the last one I saw on EBay went for £50+! What really annoys me is that because collectors with more money than sense push prices up like this, people like me, who want to USE these engines, not look at them, don't stand a chance of getting one! I had a DC Wasp too, which, as you say, was more a glow converted diesel, EVERYONE bought one of those, because they were about £1.50 brand new! They were an attempt to compete with imports like the Cox .049, which wasn't much more expensive then.

Wilf

**RknRusty** Tue Nov 15, 2011 8:09 pm

To prevent the needle valve from sucking air, you have to do this:
.049 Medallion from EBay Needleseal

The older the NV the worse it gets. It'll be all over the place if it's leaking air. Throw out the spring and cut a piece of silicon tube that fits over it. I cut it to the length of the threads plus the height of the boss it fits over on the carb assy. The Medallion looks a little different, but same concept. Use a washer at the top like in the picture. A killer Bee Needle with the yellow plastic extension helps keep your knuckles out of the prop too.

nitroairplane Wed Nov 16, 2011 1:31 pm

Ivanhoe wrote:
nitroairplane wrote:Wilf a few British companies did make small glow like DC of the Isle of White I have a DC wasp that it a little glow engine but is built a lot like a diesel and doesnt run too well.
Did you ever own a DC Bambi?
I wish i did

Yes, I had a Bambi and also a Frog 50, the only two engines I could never get to run! I gave both of them away, by 'eck I wish I had them now, seeing the ridiculous prices collectors pay for them! I have an old advert for the Frog 80 diesel when it was first produced, price new 45/- (£2.25) the last one I saw on EBay went for £50+! What really annoys me is that because collectors with more money than sense push prices up like this, people like me, who want to USE these engines, not look at them, don't stand a chance of getting one! I had a DC Wasp too, which, as you say, was more a glow converted diesel, EVERYONE bought one of those, because they were about £1.50 brand new! They were an attempt to compete with imports like the Cox .049, which wasn't much more expensive then.

Wilf

I would give most of the Cox engines I own for a Bambi!
I got several tiny diesels including the Dave Banks VA Bamby replica it is a little low on compression but still runs good. Yeah man I love old English diesels especially the tiny ones and i was one of the only people to actually get a clan .24cc running!

also got a frog 100

and a terrible AE

A diesel pee wee .020

and soem other stuff thats not recorded.

Ivanhoe Wed Nov 16, 2011 5:18 pm

I would give most of the Cox engines I own for a Bambi!
I got several tiny diesels including the Dave Banks VA Bamby replica it is a little low on compression but still runs good. Yeah man I love old English diesels especially the tiny ones and i was one of the only people to actually get a clan .24cc running!

also got a frog 100

I have a Frog 100 too, it was given to me with a mangled conrod, I had a new conrod made, but it still has some other problem, I think the big end pin on the crankshaft may be bent, but whatever it is it won't run, I can get it to fire with the electric starter but nothing I can do will pursuade it to start! I suppose I could use it for noseweight!

Wilf

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