Haven't been in the hobby very long. running a Saito 91 with an OS F glow plug. I flew today and noticed that the glow plug has a black deposit not on the coil but the very base of the plug that extends into the cylinder. I didn't notice that last week and wonder if it means that I'm running to lean or maybe too rich. I using 15% nitro and all synthetic and for after-run, Marvel Air tool oil. Also notice that there is dark discoloration on the muffler. No doubt the Saito and muffler run hotter than my os46fx. Also noticed the same dark stuff on the plug but both engines run great. Thanks in advance...

Ed

Sarge,

It is running correctly, there's nothing wrong with your engine.

Enjoy

Jim

Hi, Jim...

Thanks for your response. I was a little concerned because up until very recently the bottom of the plug was squeaky clean. Maybe that means I need to get more air time. But I guess the old adage 'if it ain't broke, don't fix it' applies here....

Ed

Don't worry Sarge:

Everything is fine. Just remember - every cycle you have a tiny, little explosion inside the engine. Some dark cover there is because it is impossible to have perfect fuel mix all the time (remember you go slow, you go faster... full throttle...). As a result the fuel does not fully burn, leaving some residue not only on a plug but on all other parts inside the engine.

As far as I know F plug is the best one for this engine.

I am not sure (and this statement is out for discussion), but I read somewhere that it is better for the engine to have at least some castor oil in it (e.g. 80% synthetic, 20% castor).


Have a good flying!

ekrcflyer...

Appreciate your input and explanation makes lots of sense. I learn something every day...


Thanks

Ed

If you use a fuel formulated for 4 strokes, it will definitely be short on oil. The Heli fuels usually have a good bit of oil in them.

Try not to use fuels that are all caster. It tends to cake up the black stuff on your exhaust (both sides). But some caster is great.

Most of the people around here (the casual sport flyers) just use regular 15% fuel. But the macho 3D boys use 30% heli.

Enjoy,

Jim

Jim...

The guy at the LHS recommended fuel with all synthetic oil. From what I understand castor oil has a tendency to eventualy gum up the valves, lifters etc. But I do run it on the rich side anyway to be on the safe side and it runs great. I'm using Cool Power 15% and it's green in color.

Thanks...


Ed