Here's a pic of mine with one of Ralph's G62's in it. No over heating problems at all, but I do have a bit more opening in the bottom than you. I used to have a DA50 in it with a pitts muffler, so the bottom is all open where the muffler used to be.

It looks like your G62 is one of Ralphs. If so, you need to check the neoprene hose that Ralph used for the pulse line going to carb. Mine was only a year old or so and looking at it, it appeared ok. Take it off and stretch it and it was full of cracks. A buddy of mine was the same way. This could very well be your problem.....