I don't know if it counts, since it's not really a motorcycle, but this was my first ride:
(not actually mine in the pic, but almost identical)
It's an Area 51 scooter by Aprilia which my parents bought me nine years ago. Two stroke carburated 50cc engine (electronic injection in scooters was unheard of back then), dual disk brakes (was quite the exception), inline suspension, LCD display, various bells and whistles. It used to be the finest 50cc scooter money could buy. When I realized how expensive it was I told my parents to get something cheaper, but my dad liked it so I got it anyway
In Italy many young scooterists like to tune the snot out of their rides, transforming little 50cc buzzers into 80cc shriekers that guzzle gas at an alarming rate, accelerate like mad, get to speeds in excess of 120 km/h and would never pass any mandatory servicing if it wasn't for the complacency of some garage shop owners who turn a blind eye.
Me, I always left it stock. I did remove the restrictions that forced it to 45 km/h, so it now gets to 75 or thereabouts, but I did no other modifications.
I recently replaced the old, rusted, clogged exhaust pipe with a new one, made some repairs and some maintenance, and now it runs like new.
If the scooter doesn't qualify as a motorbike, then my first one is my
Kawasaki ER-6F, known in the usa as Ninja 650R: