This was my first....bought as a basket case and put it together....ran poorly, siezed all the time, but got me started on motorcycles.
http://bikez.com/motorcycles/yamaha_yas_1_1970.php 15 HP!!!!!!!!!!!!
This was my second: ran like a scalded cat!!!
http://bikez.com/motorcycles/suzuki_gt_250_1973.php 31 HP!!!!!!!!!!!