Not really. Indonesian traffic cops in general and Balinese traffic cops in particular love shaking down motorcycling tourists and not having an IDP means an "instant fine" for you. Also note that you must have a motorcycle license in your home country and an IDP that covers this, an ordinary car license won't do.
Then again, given that you can usually get away for Rp 50,000 (~US$5), if you're only there for a short time you can do the math to figure out which is cheaper. Rental agencies do not care either way, although any insurance you may have may be invalidated if you don't have a valid IDP.
(And no, I wouldn't usually recommend breaking the law, but if you're a licensed driver with a license in English, this silly insistence on expensive additional pieces of paper is not much short of a scam in itself.)