The stock is 14t. There are a lot of people on here who love the 13t. I am not one of them but it is to each there own. I would check the air filter every time you ride. It is very easy to clean and you would be surprised how much it will help your motor. I would get the valves checked when you get the oil replaced. It isn't that much more time and the last thing you want to do is suck a valve. The other thing I would pay particular attention to is the Valve guides. When we pulled the head on ours we had several that were cracked and needed to be replaced.