Hi, I would advice against taking your bike across as you are exposed vehicle import fees at the foreign country port. And you need to have insurance cover from the moment you land in. To not to engage in these complications, you are better with hiring a bike locally. I am sure there will be a few in colombo. If you still like to take your bike, you may check with the ferry company operating from Tuticorin harbour..I am not sure if there is a ferry between Madras and Srilanka...
Thanks this is helpful ..