I amabout to install a satio 150 inverted on my spacewalker ..I worry about fuel in the head sitting but I am told just install a remote ignitor and problem is solved.or you can do noting and you can even install a pump$$$..someone even suggested just offsetting the invertyed engine 5 or 10 degrees.I suspect I am worrying over nothing but all these years I have avoided inverted engines but am plunging into it now.