I like this category :D
I've owned only very few bikes in my life. This one I bought brand new in 1984, a Yamaha XT 600 (Type 43F).
(http://www.nebdaar.com/temp/xt600_1987.jpg)
Pictures from around 1987
The XT 600 with the small gas tank was just been released. It was somewhat a paradigm change in road legal enduro bikes. 600 cc in a single cylinder! Spring travel like mad, single shock suspension in the back. And those colors: red seating, red frame. I remember how others asked "Hey, that 600 you just sticked on it, right? That's not really a 600, right?". Fun times. I was young and had some serious fun in the dirt. I've never been a MX rider, more a casual rider whenever I found a dirt spot to ride on.
Well, I've got old meanwhile, hitting 52 this april. I'm not riding in the dirt anymore. But guess what, my old bike is still with me ;D Just rode her yesterday (we lack a bit of winter around here). Fun reliable XT 600 43F :)
(http://www.nebdaar.com/temp/xt600_2015.jpg)
Picture from 2015