Hi, I will be in Kuta in July, so I want to rent a motobike to go around. But i don't know whether there are some problems if a foreigner ride a motobike in Bali (will i get hassled by the police?) or not.
Please give me some suggestions.
This piece on how to avoid motorcycle fines in Bali may be useful. Aside from that, be sure to check the bike over properly, wear a helmet, and you are legally supposed to have an international riders license.
I ride a bike regularly and haven't been pulled over in ages - it helps not to dress like a tourist.
As Somtam said, if you don't have the correct licence you are riding illegally. And that means you have to pay a fine if you get pulled over by the police. If you crash and kill someone, you could be in all sorts of trouble with the law. If you crash and injure yourself, you may not be covered by insurance as you're committing an illegal act.
All that said, a lot of people ride motorbikes in Indonesia without trouble. Expect to pay less than 25,000 rupiah per day for a semi-auto bike if you take it for a month. It can climb as high as 50,000 rupiah for shorter-term rentals of new/auto bikes. Whatever the case, it's cheap.
Another tip to avoid getting pulled over by the police is to wear full length clothing such asjeans and a jacket. I know it's as hot as anything, but it stops you from getting burnt and it's what the locals where. You'll blend right in.