You will be able to find a guy to rent you a bike without the proper licence but if you cannot ride the thing then you are going to have problems and possibly an accident. Driving in Pattaya is a nightmare especially on a motorbike. As has been explained above you need eyes in the back of your head to watch out for the idiots who they let drive in Pattaya. I have rented a motorbike many times there but I have over 20 years experience and have had no serious problems and thankfully always had CBR's which had very good brakes.
I have had some berk in his car driving about a foot away from my back tyre,he was chasing me down 3rd road,I lost him as his car was not as fast as my bike. I have had a few people just pull out on me when I was a few feet away from them and various baht bus drivers pulling out without even a look. Plus the roads in Pattaya can have huge bloody holes in them so if you are not concentrating then you could have a serious accident and be hospitalised. Also there are many drunk people driving and riding in Pattaya. If you did rent a bike and had an accident and smashed it up then they will expect you to pay for it,as expalined above you could get shafted if you are in any accident with a Thai.Stick to the baht bus,its cheaper and safer.