I started in March of 1964 on a brand new Honda CA110 50 "Sport" (OK, OK, it actually belonged to my older brother, but he almost never rode it). Then it was a Triumph Tiger Cub 200 that almost never ran. On to a '68 Honda CL350 during the high school years. Beat the crap out of that one, but had fun doing it and, as a side bonus, learned how to split cases and replace transmission gears. To this day, I think I have as much fun working on bikes as I do riding them.
Next came the Motocross years: A '72 Yamaha MX360, a '74 MX250 for starters. A couple more used MXers: a CR250 and RM400 along side a friend's Montesa Cappra that dated back to about 1970.
Also had a '68 Bonneville during that time. Great bike that I wish I still had (along with the Tiger Cub), even though it had lost its soul to Lucas, Prince of Darkness. Pushed it a lot, but when it ran...
Got married and "retired" from Motocross - not exactly my idea - but it didn't last long (the marriage, that is). Next wife is a keeper. Had her own '78 Honda Hawk and, later, a hot little GS250 Suzuki. I picked up a new 1980 XS650 Special II. That was fun for a while, but was quickly replaced in '83 when the XJ900 Seca appeared as the answer to my sport-touring dreams. Still have that one - Eclipse soft luggage and all - but the bike is in resto/project mode at present. My Sprint ST is the daily rider and how I love that motor. My son and I swap bikes sometimes, though, and riding his Street Triple reminds me a lot of my old 360 motocrosser. They both have about the same power to weight ratio!