The most common way of transport in Sri Lanka is a three-wheeler, it also known as Tuk-Tuks. These operate in a manner similar to taxis, and in many situations are a convenient and highly cost-efficient way to get around. Some of them are metered and some are not. The best price you can get is about Rs 50 to 75/km for short journeys and about Rs 30 to 50/km for long journeys.
You can rent motorbikes in Sri Lanka, but you must have a valid motorbike driving license along with valid third party insurance and must wear helmet including the pillion passenger and local police will require you to switch on the head light even on day time.