Tuning/.... Glow plug????

[ejp]

So, I was having a hard time getting my MM 21 to run good. It would go pretty good as long as I kept some rudder on but it would slow down in the straights. I moved the needle 1/32 either way and it would run worse. It seemed to maybe be too rich but then too lean. Would a hotter glow plug at the same needle setting change anything??? I am running the stock o.s. 8.

[mustangman05]

i dont know if that would change it or not what is you high end set at?

[Watercadet]

That is too lean or over proped or strut too deep or pipe too short or ....etc. Start by fattening it up more. When you think it is too rich, richen it up some more. What fuel and plug are you running? If you are in the 10-40% range use an OS 8. Remember that OS uses short plugs and using a long reach plug will up compresion and change the characteristics of the combustion chamber. The OS A3 will hold up well to about 30% nitro too.

[ejp]

I am running 25% and I think the pipe that is on it now is a piece. I have an irwin on the way so I'll try that. I put an OS 8 in it just the other day, Haven't got to run it yet though. I might have the strut too deep also I guess. The prop is a x437x3 so it shouldn't be too big for a .21 should it???