just bought my daughter beta rev50 2003 model clutch bike anyone know how many cc of oil and what wt of oil?

Call beta usa they can answer your question, unless you want to wait for a reply on the internet. Or you may be able to download the manual from the factory beta wed site , look under down loads.

http://www.betatrialuk.com/content/view/68/51/

Try the UK beta website, the info on the smaller bikes doesn't make a lot of sense to me, not being familiar with the model variants.

As a rule drop the oil out and have a look at how much comes out to see about how much should do in. Does the rev50 have a oil level viewing window like the rev3s?