After having lived in Japan for some time, I decided, in January 2013, to buy my first motorcycle. My first 2-wheels vehicle was a simple 50cc scooter, Honda Dio, equipped with a 4-stroke engine. It was terrible! Even if I modified it a lot (exhaust pipe, air filter, CDI, CVT, pulley and so on) it could barely reach 60km/h. After that, I decided to move to a 125cc motorcycle, and I bought a Kawasaki D-Tracker 125, which was not so bad, but it was not powerful enough to reach more than 100km/h.
After obtaining the Japanese Motorcycle Driving License (大型運転免許書), I tried, for a short period, a Ducati SS900. I have to say that it was a wonderful motorcycle. 2 cylinders, 900cc, 80hp, very nice brakes and good frame, that was awesome. But unfortunately it was too big and heavy for my daily rides into Tokyo and Yokohama, so I decided to go for a smaller one again, something which could be easy to ride inside the traffic (<150kg). And also, I wanted to have a motorcycle which I could park everywhere (in Japan, most of motorcycle parking areas are limited to 125cc). Finally, I was also looking for something not too slow, capable of reaching at least 110-120km/h, with a decent acceleration.
That's the reason why I decided to buy a Honda CBR125. It has a 125cc single cylinder 4-stroke engine capable of delivering 13.3hp @10,000rpm. Also, it is very light (about 130kg), which makes it easy to ride it in the traffic. I bought it used for 200,000 yen (1500 euro) on Craigslist Japan, with only 2,400km on it.
If you are used to ride powerful motorcycles, you will find this engine very weak. But in my opinion, it is more than enough to fight against the traffic of Tokyo, in which you rarely reach speeds higher than 90km/h. The engine can deliver enough power to ride at a decent speed of 120km/h (my weight is 70kg). I used it for 8 months up to now, and run more or less 1,200km. I use it to go to work in Shinyokohama, mostly everyday, when it is not raining.
In conclusion, I am really satisfied with this motorcycle, and I would recommend it to everyone who needs to ride everyday in the traffic, but don't want to have a scooter like most of the people. Also, if you are looking for a small motorcycle to learn how to ride a motorcycle, I am sure this will fit you.