Join Date: Jul 2016
Location: Seattle, WA, USA
That rattle is the Hydraulic Timing Chain Tensioner has lost it's oil while sitting then once started, fills and snugs up the slop in the chain. I personally haven't had it happen but a riding buddy developed it in his '05 K 1200 R. He replaced the tensioner with a stock unit ($$$). There is an after market job that is spring loaded but I have no personal experience with them; Sounds like a good idea if it's decently made.
The biggest concern about the problem is that if it get's bad enough, You can start jumping teeth on the sprocket. These are high interference engines, meaning if they get out of time, valves start hitting the tops of the pistons and valves start hitting valves. The valve heads break off and fly around in the cylinder and combustion chamber. if a valve head get's stuck edgewise in a piston, it has nowhere to go so the con-rod gets bent to shit as well and there goes your lower-end. It's all over but the pissing and moaning. So yeah, fix this.
it's the cylindrical can about an inch in diam. standing about 2 inches high on the right side for the motor between the 2 front upper motor mounts. it's held in place by 2 easily accessible bolts.