There is a large hose running from the top of the engine to the bottom side of the top of the spine frame. The hose is about an inch in diameter. It is part 18 of drawing 10 in the parts catalog CD. Does anyone know the exact size? Ideas about where to get a better quality replacement? Mine has started to break down and is leaking. This may be something for people to keep an eye out for. FWIW I have 21,000+ miles on the bike now.