Hello Scott, The last day I ran some engines it was around 60 degrees so it wasn't the temperature, I don't think, was giving me problems. I suspected that the carbs I was using are the problem so that is what I will concentrate on getting right. From what you are saying about carbs, that has to be my problem. I will get it all straightened out one of these days. When you get the right carb on a single cylinder engine and put some time on it, the old inspect the plug for proper combustion idea, will probably work with these engines as well as any other. Time now to catch up on building.