NO cooling problem, if you look at the one with a cowl you will see how much of the bottom of the cowl is cut out. Ok Folks I will have my test engine this week and plan on flying it over the weekend. If all goes well we will be selling the engine in about 3 weeks. I also will have the Edge, Yak and Extra 260 all in the 26cc class in late Dec. Here are a few pictures. Our Engines will come with a wrap around pitts muffler and a rear mounted carb.