Originally Posted by
thailazer
Jim... Thanks for those points. The prop seems heavy enough, and we did try a OS #8 and an OS #6 with no difference in the quitting. We first thought that it was loading up at idle so we leaned out the low speed mixture so a pinch on the fuel line has less than a 10 second run. It seems like something is quenching the plug or there is detonation at the wrong time as it stops so suddenly.
You mentioned that you had problems with your carb.... Can you elaborate on that?
I believe nearly 10 seconds with a pinched fuel line is way too much! I t should not run more than 4 seconds when pinching the line close to the carburettor.
While in mid range both needles feed the engine. I think your engine is running too rich (both needles), and the plug is getting cold in mid range. 15% of nitro is a waste with so big engines.