Nobody got the info correct.... The first K&B 7.5 ducted fan engines were rear exhaust and front intake design...They incorporated Perry Pumper carbs and a Perry pump mounted in the rear of the crankcase...Real pieces of garbage in my honest opinion....Second generation K&B 7.5's were rear exhaust/rear intake---Better design, more power, and a little more user friendly but no match for the OS engines---Especially the latest version of the little OS as it is one sweet engine. Excellent, reliable idle and will really scream!!! The last version of the K&B was the 48, but as previously stated was only a limited production run...

Kevin