I have a Moki 120 that will run great for about 3 flights and then will not start because the glow plug gets damaged. After much trail and error the motor will only run well with an OS F type plug and with a McDaniel's glow driver. The glow driver is linked to the throttle and provides glow below about 25 % throttle.

I checked the voltage on the output of the glow driver and its puting out .6 volts. Without the OS F type plug transitions from low to high throttle are poor ( like its too rich) and without the glow driver the engine will die if the throttle is cut for any extended time. Also, the glow element looks OK ( ie its not coated white nor distorted)

I've tried richening up the high speed needle valve assuming that the engine is getting too lean, but that has not remidied the glow plug problem, and as a side effect I'm also loosing power as a result. The motor is installed in a H9 Cap 232 so I need all the power I can get!

Any input is appreciated.

Have you tried it with a 1.5 volt source connected to the glow plug. Also you said it gets damaged and then you said it looks OK. It sounds like you have a rich low end and too lean top end, also an OS-F is a fairly hot plug for your engine. Are you using 5% nitro.

I'm using 10 % Nitro.

Hi,
I run the same engine in a large Giles 202. Runs superb and starts first back flip every time.
10% sounds way to much for this motor as they are european they tend not to need much, if any nitro at all. I actually run mine on half a gallon of castor straight mixed with half a gallon of 5% sythetic givig an easy 9k on a 16 x 8 APC.
Great engine. Try reducing the nitro content and add some castor if you're not already using it.

Regards,
Tony

Thanks Tony. I'll give the 5 % and castor blend a try. By the way, what glow plug are you running with?

Jack

Good question. Cant remember, though I tend to run cool plugs in most of my engines. It's most likely a Rossi cold.

Another thought. Do you have plenty of air going through the cowling? Could be another potential problem. Sounds like the engines getting too hot.

BFN
Tony