I am going to be following along with this post. 
Alamo, i have had some reports that 150cc is ok..but now a guy in a Facebook group i am part of is saying he entered 4 weeks ago on a 120cc (not sure what bike with that CC). 
Yet, same as David's comments, some have said anything under 250cc would be a problem. 
Conflicting reports..and would be good to get a definitive answer on what the minimum CC is currently allowed. 
Good luck. 
If i find anything out, I will update. 
Please could you post an update if you find out also.