Rat Bike

Slant spark plug helps with clearence on a frame that the engine does not fit into well, so that the spark plug does not hit the frame. In theory the plug could be indexed, open end of the plug pointing down into cylinder for better combustion.
It's funny about Rat Bikes of any size they kindof catch your eye. Like your bike / motorcycle senses are being accosted by an overly motivated panhandler. Safety and reason ride miles behind a rat bike.

I've looked closer though and Rat Bike in it's purest is admirable.