I have a black widow engine that is difficult to start and I would like some advice.

This engine is 15 years old. It used to run fine the first year. It was not used until a month ago. I have not changed the glow plug or cleaned it in any way. I do have fresh fuel - just opened it a month ago. It is powermaster 1/2A racing fuel so it should be pretty high nitro content.

When I tried to start it a month ago, I filled the tank, primed it (with the piston down), applied glow power and flicked it. It fired up and immediately died. I played around with the needle setting but never got it to catch.

So, the next step was to try a starter and using it, we got it running. For the next four or five attempts, I would open the needle by half a turn, get it going and then close it back to keep it running well.

Today, I spent 20 minutes with the starter, trying to get it going. Because it was hotter today (than a month ago), it turned out that the previous needle setting was too rich by a quarter of a turn and this caused it to not catch. It would burp.

As you can imagine, this is very frustrating and any help would be greatly appreciated.

I'm not looking for more power from the engine, I just want reliable starting - preferably hand flick.

Thanks,
Harjit

I went though the same thing myself just last weekend. After checking all my gaskets it still was running real weird. Changed the head and it was as good as new.

Later,
Tim

remove the glow head and see if you have a bright orange glow when you connect your battery. If not ,the battery is weak, or the glow plug is bad. If you have a good glow plug working and fuel it should start. Open the needle about 2 1/2 turns. and just a little bit of fuel to prime.

I recently purchased a couple of used Cox 0.049's that hadn't been run in quiet a while . Only ran briefly when primed. Turned out that the reed valves had glued themselves shut with a film of 10 year old dried castor oil. The reeds were the clear plastic type. Remove the tank,the reed circlip, clean the reed with fuel and rag. Put it back together and cross your fingers. It'll probably fire up.

I took the fuel tank off and checked the reed. It was clean and worked one way and not the other.

I tried to fly again on Sunday but the engine still didn't behave.

For the glow driver, I am using a remote start adapter plugged into one of the one (NiCd) cell drivers. I use a cotter pin on a short wire to attach to the glow plug. The glow is nice and orange and when there is fuel in the head, you can hear it sizzle.

I had another plug, and when I tried it, the engine fired up better but still wouldn't catch. Not sure how this is relevant but the two plugs I tried had different markings. One had lines coming out of the top surface and the other didn't. Are these lines significant ?

Sometimes when I had the starter on it, it would turn over and it sounded like there was no glow but I knew there was glow because the ampmeter was showing current flow.

It seems like the needle was very sensitive. It would run well for just a little bit and then die.

So, I had a baby bee engine and I moved the needle valve from it to the black widow. The engine seemed to run better but again it wouldn't run for long.

We tried Cool power 15% fuel and the engine didn't run any better.

The conclusion we were coming to was that the engine must have an air leak. Where should I look for what ?

How do you seal the tank to the back plate ? I was thinking of using some epoxy.
Where do you get backplate gaskets ? gaskets for the venturi ?

Thanks.

There should be a paper gasket between the tank bell and the crankcase and a small rubber one in a groove around the center tube between the bell and the backplate.

But, and sorry if this sounds silly, it sounds from your description that you expect the engine to start and run without touching the needle valve at all. It's normal to richen it up by 1/2 to 1 turn for starting and then lean it to the peak once running.

Like I said, pretty silly but I figured I'd mention it just in case.

If this isn't the case then I'd suspect crud buildup in your needle valve metering area or in/on the reed.

I'll try cleaning everything again.

I did try opening it up by half a turn for starting and then leaning it out but it seemed that the half a turn was too much.

It seems like it is too sensitive to the needle settings which is why I am wondering if I have an air leak...

Zeetah:

My experience, for what it's worth, is that when Coxes sit for a while the fuel passages in the tank backplate get either partially or fully clogged. This can be either corrosion OR gummed castor oil.

If this is the case the needle will be extremely sensitive.

To cure gummed castor, pull the backplate, take the fuel hose and needle valve off, soak the plate in acetone for a half hour or so. Then use a very fine wire to probe the passages and soak it for another half hour. Then probe it again with the wire, and flush it with fuel.

If it is corrosion you'll need to get some very small drill bits to clean the passages. The bits will also make a much faster job of cleaning gummed castor.

Cured several this way, the 02s seem to be even more prone to this than the 049s.

HTH.

Bill.

I got the engine running quite well. The changes were based on the suggestions above:
* Replace reed valve - made one with floppy disk cleaning tab
* Replace venturi gasket - made by slicing fuel tubing. Very hard to slice evenly!
* Soak and clean backplate
* Put fuel tubing around needle to prevent air leaks

Now the engine starts and runs very reliably. Thanks!