The rules on learners for motorcycles appears to vary a bit from state to state. For SA and VIC at least, you can ride an approved one in the list up to 660cc, and most under 250 are approved (the list appears identical).
I don't reckon the indo coppers would have a problem, but if you got into an accident on a bike to high powered for your licence, your travel insurance might get cranky. But from looking at the list, and seeing the bike my mate drives on his learners (its freaking BIG, but he does weigh about 350lbs), I suspect there are not to many bikes avail in bali that would be deemed as too big.
Approved motorcycles for novice riders : VicRoads
I hope I clarify this correctly for you tiggy , when you say "approved up to 660 cc " this means lams approved - ie; although the bike maybe a 650 cc , its engine has been mechanically restricted to run with the charicteristics of a 250 cc or less motorcycle . This is called lams restricted . After you are granted an open licence , that lams restricted bike can then be tuned up to remove the lams restriction , thus having its 650cc power .
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When you get an international motorcycle licence from Australia ( or anywhere ) , it will usually be stamped either ; open or restricted ( 250 cc or less , or lams restricted is the same also ) ....., or similar ....,
In Indonesia , the police wont know the difference between the two , or even know if its a car or a motorcycle licence .
One important thing to be aware of though is if you have travel insurance and you have a serious accident (as alphonso pointed out ).
Say you are medivacced home after your serious accident to Singapore or Australia , or wherever .......,
The insurance company will be looking for loopholes not to pay out for you $70,000 AUD medivac flight home .
The insurance assesor will be digging deep to make sure you where completly abiding by the law ( ie; licenced for the bike you had the accident on ) If your licence classification didnt match the engine capacity , or worst still you were not licenced to even ride a bike ...., then you can bet on the insurance company will not be paying out for your claim , as this would now fall under " partaking in an illegal activity " and you would either be left here in indo high and dry , or have a very huge bill to pay . It only takes a couple of phone calls for the insurance assesor to find out all this info ........, be carefull