I have about 35 flights on a Saito 1.25 powered Fusion. I have been having trouble getting it sorted out. It will harrier along about 1/3 throttle. While pulling the plane along the mix looks way rich. You can see the smoke in turbulence behind the wing, it's so thick. Not being an expert I was never sure if the rich setting was on the high or the low end. I did know I could not find the sweet spot. If I leaned the low end even 1/16 of a turn, it would not start. If it did start it would die when I tried to advance the throttle. My Saito experience told me this was too lean. If I leaned the high end any it would occasionally die or stumble when I hammered the throttle to do a pinwheel or a waterfall. Even so it still looked way rich at certain throttle settings. So yesterday I pulled the plug to look at it. It looked normal till I put the hot shot on it. The last 2-1/2 coils at the piston end did not glow. Maybe this is how they always go bad? Anyway after that long description, I put a new OS "F" in it and retuned it. I can't remember the last time the engine pulled that hard.

I'm not new to glow flying. I have been doing it 19 years now. I just can't ever remember a glow plug acting this way. Most plugs I haved changed either would not fire, or I changed them trying to chase down a problem. Anyway, it was interesting to me.

David

A weak glow igniter battery can produce the same effect you just described. First few coils will glow and the last couple out on the end of the plug will remain cold.

Not saying thats what happened to you. I'm sure you are correct that your plug was weak.

Just pointing it out for newbies who may not realize the problem lies not in the plug, but the battery that lights the plug.

Good point. I did plug the new plug into the hot shot before I stuck it in the engine.

David

I had kind of the opposite problem once. I decided to start an engine I hadn't used for some time just to freshen it up before going out to fly. Filled the tank, primed, turned the prop over and felt a healthy "bump" so gave it a flick. WHACK!....ouch! Gave it another flick...WHACK...ouch! Strange because this engine was always so easy to start (it's a CL .61 so none of this whimpy idle thing ). Now I can flick an engine over pretty fast (50 years of practise there ) but about 10 whacks later the light started to dawn that something was wrong so I pulled the plug to check it. It was pulsing quickly from orange to white hot which kind of explained things because on a heat range scale it was approximately a supernova . I fitted a new plug after I checked it was glowing properly (thinking my power panel might have been acting up) and one flick had the engine purring like a kitten. It's possible an electric starter could have got the engine running but with the ignition that far advanced the engine would have been in detonation heaven.

If you have a lot of smoke at when the needle is peaked out and the plane acts like it is too rich, then your glow plug may be too hot. I have noticed when this happens I get better performance and fuel economy when switching to a cooler plug, but it will be slightly harder to tund. A Fox Miricle plug is slightly cooler and a K&B 4C is cooler yet. Or you can use lower nitro fuel.