Honda Trail 90's, and the old Yamaha snorkel cased 80's and 100's had neutral at the top, not that odd at all if you've ridden them for years. I actually prefer it to having it hide between first and second.
The TS 90 was a sweet little bike for it's time, and a good performer. One way to gain a few small ponies without changing the bore or carburetor, at least for the iron cylindered ones, is to polish out the roughness in the transfer ports, and have a machine shop take a few thousanths off the head. You will have to richen it a smidge on the main jet. Mine ran so great a friend's felonous stepson stole it from me.