Model hit or miss ignition fail

[dkwflight]

Hi
THe red print on the ceramic say Champion :<)
Sorry about the poor close ups
From the comments these pics will show the size of the plug.
I have a similar plug coming with a plastic insulator.
Remember the threads are 1/4" x 32 TPI

 

[Steamchick]

Thanks. I had a quick look on-line to learn there is just one plug type in this size. It comes from various makers, but always for RC petrol engines. These run at high rpm and continuously, so need a good heat path the keep the plug from overheating. But you really need a different heat path plug that doesn't take the heat away very quickly, so it gets hot and stays hot to burn-off any carbon. But if there is no alternative plug you'll have to live with that heat grade.
Also, you need to get rid of the surplus carbon by leaning the mixture much more. It is far too rich. Like an engine running on full choke all the time.
Enjoy the tuning, learning and running the engine.
Well done fixing the intake valve spring issue. Hope it lasts.
K2

 

[dkwflight]

Hi
I have had the head off several time playing with the intake valve spring.
The carbon was very soft and when I got the mix very rich the gas would flush off the carbon.
Since then I have washed the plug with a solvent and blew the end with high pressure air. This cleaned enough carbon out of the plug to get it firing properly again.
At times it seems like I have solved the extended run problem. Then it quits.
I am now wondering if there is some dirt in the mixer/ carb. I will blow that out too.

 

[dkwflight]

I got the new spark plug. I was surprised to find if the new plug was screwed in tight it was hit by the piston.
I drilled out a #10 flat washer to 1/4 and that was space enough to stop the interference.
The mix had to be enriched some to get the plug to fire.

 

[dkwflight]

Hi
I finally got a full run on the engine, tank full to empty.
I am running the original Champion VR 2 plug. This plug has a central point. The spark jumps to the thread edge.
The corian plug, the central pin went almost to the thread edge. A "J" shape. .a very short spark gap. They called this plug a side fire.
I got another plug that is doing better/ leaner.
http://sparkplugs.morrisonandmarvin.com/vr21.php