I have finally found out exactly what that bike was I saw 20 years ago.
Honda’s American CB900 would not be so long of wheelbase, nor mechanically quite so interesting, if those who designed it had not chosen to use a maximum of existing hardware. Specifically, they opted to work with only lightly altered CB900 nee CB750F engine/transmission cases and the GL1100-CX500 final-drive assembly. This approach, like making the CB900 out of the CB750F, was shaped by manufacturing economics. They had to couple a left-side transmission output stub to a right-side final drive, and the twain could not be made to meet without taking complicated measures.
What Honda’s engineers did to resolve their right-to-left dilemma was to cobble together some transfer gears, a jack-shaft and right-angle bevel drive in a housing that wraps around the left side and rear of the main transmission case but is not inseparably a part of it. They also doubled-up the transfer gears, which occupy space originally taken by a sprocket, and added a shifting dog, etc., to give the CB900 a two-speed secondary transmission. And although the entire exercise was prompted by cost considerations they did not stint in building reliability into their cross-over drive unit. It is a very strongly constructed piece of equipment, with its own oil supply and a small trochoidal pump to keep its bevel gears lubricated; splash oiling takes care of the transfer gears.
There certainly was some justification for the two-speed feature of the drive. Gold Wing owners never have been able to agree on the overall gearing their bikes should have: some want the ratio “tall,” for low-stress cruising; others, habituated to hauling big loads and pushing bulky fairings, prefer the shorter gearing that lets them pull steep grades without downshifting. The CB900’s Select Range feature provides two overall ratios. There’s a 5.26:1 ratio (in fifth gear) for mountain or urban conditions, and a 4.50:1 ratio for economical cruising.
via Honda CB900C.
