All right. A few things you need to be aware of.
1: the clutch operation is entirely mechanical in nature. There are not one, but THREE sperate adjustments that need to be performed periodically to keep it running properly. Information on how to do that can be found HERE:
http://www.volusiariders.com/58-motors-transmissions-drives/170041-free-perfect-your-clutch-manual-page.html
2: Since this is a new-to-you bike, how thorough were you on your pre-purchase inspection? Did you look at the tires for the manufacturing date? It is stamped on the sidewall. It will be a 4 digit number XXYY the first two being the week of manufacture and the last two being the year. If they are older than 2009, then you absolutely need to replace them ASAP due to age. Rubber degrades with time, even if it isn't used.
3: Did you do any of the other checks that were recommended to you before you bought the bike?
4: When you bought the bike, did you check the oil level???? You have already had to top it up, which means it was either under-filled on its last oil change or it is burning oil. It is not uncommon for these engines to do so with age, because of poor upper cylinder lubrication. Keep an eye on your levels and if it is low, top it up as needed. Also, keep track of how much it is using between changes as this is an indication of the level of engine wear. Switching to a thicker oil or a different brand won't help.