I've had a noise I believed to be the timing chain worn, a small light tick tap kinda sound. but yesterday on the way to the river (about an hour ride) not long in I notived I have a new sound. much more dominant and defined of a sound. I'm going to try and describe it best I can but might just add a video for better results. there is no sound during idle or at low rpm say 5th gear, 20 or so mph but during acceleration and holding a higher speed or higher rpm there is a constant very high speed knock. not extremely hard or painful almost sounds like a rattle. I believe it's from the top end area but didn't pin point it. I can also hear it in the crankcase vent on my snorkel but its faint which leads me to believe its not in the bottom end. I'm wondering if it could have jumped time and is slapping the piston on the valves or maybe the piston has too much play on it but I don't see that randomly happening. it rode fine the way there other than the sound but on the way home started to miss fire I believe. be riding trying to avoid the sound so low rpm but the bike would bog for blink then go for maybe 20-30 seconds another bog ect. any ideas where to start this diagnosis?