My '15 350 EXC-f approaching 150 hrs...99% single track. Manual calls for a top end at 150 hrs, I believe. I ride most Saturdays from Dec 1st to Sept 1st, but she sits with a tear in her headlight from Sept 1st through Thanksgiving. I average about 50 hrs per year on her, run Amsoil 10/50 synthetic and change the oil & filter every 15 hrs. Wanting to avoid her being down during "riding season", I had planned to have the top end done before saddling back up after Thanksgiving. However, picking through posts, I find several references where top ends have not been done until well over 200 hrs. The bike doesn't smoke and runs like a champ. She usually takes a few pushes of the button to start when cold, but when warm, never fails to fire right up. Now I'm hesitating to follow through with my top end plan. Really don't want to dive into the engine prematurely. We've grown quite fond of one another, so want to extend her life as long as possible. Will much appreciate thoughts from you seasoned veterans out there. Thanks!