I had an old Honda 400 with the "hydromatic" for a little while years ago. Damned thing was barely road worthy. (I only paid $100 for it)Tires were dry rotted. I pushed my luck and one day BOOM goes the back in a turn. Interesting to say the least. It had two gears, a sort of low and high. You still had the shift peg but didn't have to use the clutch, even though it had one.
Ok... I had allready googled it but couldn't really find any info on what was up with HD and HydraMatic... So, here's a coupla pics of what I saw on the street.
The blonde is a gift for all your helpful replies.
It could be a bike hydrostatic clutch. It allows you to use or not use a clutch. As the RPMs comes up the drive engages and the bike moves. Saw one at a dealer once.