I went out for a day of riding and on the last ride got up to the top of a hill and it started knocking lightly. I pulled the clutch lever in and stopped, powered off the bike, then fired it back up. The knocked stopped then I started heading back to the staging area when the knocking started again, this time it even did it just idling out of gear. Anyone have any ideas? My guess is a valve but why would it start so heavily and out of nowhere? Any ideas and suggestions would be greatly appreciated.

Thanks!

 

Valves don't knock. Click or tap, but not knock. Could be a few things, but the rod or piston comes to mind. Get a hose and listen where it's comig from.