I have a new style 3w 100 thats turning a 3w27/10 prop at 5900 rpm. on my first flight it was cutting out every time I went into a knife edge or inverted. then after about 8 min of flight it would start losing power. After landing the the engine didn't feel hot at all like it was overheating. it is baffled. is it running to lean?

Welcome to the world of midrange maladies and gas engines. I'm breaking mine in on a 26x10 and petroleum based oil and it's fine so far. What are you using and how many gallons of fuel has the engine seen? If spank brand new, give it a couple of gallons to settle in. If it's still rich in the mid range, try one of the carb fixes listed in the 3W literature, or search on the board for them. Basically you can add a vent tube leading to the venturi, a vent tube leading into the fuse, a carb shield, or the 3W horn. I've settled into the horn on mine and it's perfect. Takes a little fiddling, but it can be worked out with some patience. Let me know how you make out_bob

bob I have the carbon fiber horn already. useing lawnboy ashless oil and have not even ran a full tank through it yet. 4 8min flights.

Where's your lo speed needle?

They make a carbon fiber intake as well that will fix midrange woes, I think around $50 from cactus, I have one nib I will let go for $40 shipped, dont need it any longer.