1999 k1200rs - making strange noise

I have a k12rs that is making a strange noise in the front of the engine. Sounds like a boxer engine running. The "box of rocks" sound that the K makes on startup is how it sounds constantly now. More of a putt-putt-putt-putt than the normal whirring sound of a k engine. Seems like it is also down on power a bit. Also seems to be running slightly hotter than normal.

Problem showed up riding on Friday down the Blue Ridge Parkway. Been on a 3 day camping trip and the noise showed up suddenly. Limped it home and now trying to figure out what the problem is.

Any ideas anyone?

Thanks

You don't mention the mileage of your bike but I suspect something in the cam timing, such as a tensioner or guiderail, is worn out. The K-1200 engine's long stroke and short conrod combine to whip the cam chain pretty violently, which is why the the 1200's have much heavier guide rails and tensioner than the other K bikes. I would look there first.