My wife and I recently returned from a 15-day trip to Indonesia. I've made the trip several times with a foundation I help manage, and have always been fascinated with the culture of motorcycles over there. Some interesting observations of the Indonesian world of two wheels:
The largest displacement engine I found in Indonesia was 250cc. It's an interesting contrast to the US, where, aside from scooters, a 250 is about the smallest you'll find.
The rider almost always wears a helmet, yet often passengers do not. Even multiple family members, including small children, will be helmetless, while the "wrist" will wear one.
We spent a few days in Japan prior to continuing on to Jakarta, in and around Tokyo, and out to the countryside surrounding Mt. Fuji. I was startled to find very few motorcycles, including scooters, in Japan, in the city or country. Ironic that the nation with four of the top producing brands in the world ( Honda , Yamaha , Suzuki , Kawasaki ), and so few of their own citizens actually ride.