motobike in Bali

there are plenty of rental places all over, intense competition makes it very cheap (usually around 30.000 rupiah per day)
but: it's quite possible that you are not allowed to take a rented bike or car out of bali, so you should check that carefully with the owner, and also with the police (there will be check-points at all the harbours along the way)

I've taken rented motorbikes from Bali to Lombok and to Java. You'll need a letter from the owner allowing you to do so. There will be police checking when you disembark the ferry.

Yeah, no problem to take a bike out of Bali, but you do need to tell the owner so you can get the letter... Will be a great trip! Renting a motorbike in Bali is cheap - it's the cheapest place in Indonesia to rent one. Some are in fairly poor condition, but you can easily find a decent one. I've done a lot of bike exploration in Indonesia - it's the best way to see the country if you ask me (last week I spent a week travelling across Java from Jakarta to Surabaya on a 14-year old 100cc honda - awesome).

Just a thought, Ubud might be a good place to rent, simply because the traffic in and around Denpasar and Kuta is pretty mad. Ubud has lots of bike rental places, and it's a nice quiet place to start, get used to the bike and the local road rules etc.

Probably the cheapest in Bali. I rented a bike a couple of times in Flores and it was more expensive than in Bali.

I just arrived back form Flores yesterday, and the main 'highway' in Flores is pretty horrific at the moment though, they are doing works in a hell of a lot of places. Get a helmet with a pull down visor or your you will get dust in your eyes the whole way from the vehicles in front.