Hey Advrider, I am chronicling the rebuild of my 2007 690 SM LC4 engine here. Bike has 12k miles. It had a bad noise in the bottom that I suspected was the balancer bearing or maybe a crank bearing. Here is a video of the sound. It would go away after about 2-3 minutes idling, which is the strange part... you'll hear it stop near the end of the video then it sounds normal. The cam chain was tight with a manual CCT (maybe even a little tight for my judgement), so I don't think that was the source. Now on to the fun work! Started by draining the oil and coolant. Oil screen on the tranny side shown, other was clean. Cheated and used the rear brake to loosen the clutch nut since I don't have the tool to hold the basket. Next removed the motor, fairly straightforward, didn't get many pics. Toughest part was the frame pinching onto the back of the engine through the swing arm pivot. Finally split the case and removed the balancer. I am concerned about the balancer shaft grooves from the 2x seals and possibility it already allowed a little water to seep past to the bearing. Should I replace it? Closeup of the suspect bearing. It feels gritty/rough, especially compared to the other side so I am fairly certain this was the problem. Note broken oil ring. It could have broke when it opened up after coming past the edge of the cylinder but I don't think that is likely. Right case cleaned up. Left case cleaned up. A little concerned about wear on the small oil pump: Big pump looks good: Transmission gears look good, no pitting or missing teeth. Shift dogs have very minor wear Bore has 1 section with a few lines but otherwise no signs of wear. I suppose nikasil is pretty hard after all :eek1 Cleaned piston, very little wear. Photos of broken oil ring. Was going to replace rings anyway. Exhaust roller needs to be replaced (as I suspected from reading many posts). Not much movement in the bearing but the galling is a no-go. Also took apart the starter to clean/grease. Stopped here because I am concerned about holding the 4x (four!) brushes back when re-inserting the stator. Really would like to re-grease the bushing in the back though. Valves and head look good, no oil on any stems. I will remove the valves to change the valve stem seals. Intake clearances in spec, will check exhaust with new rocker. Should I look for anything else? Cam looks good. Had the non-iridum equivalent, electrode is still sharp, I will use a new factory iridium plug though. Very little play in the big end of the rod, at least as I would grade it quantitatively. I had considered having a new rod kit installed but probably won't. I have blown through the oil passages with compressed air and nothing seemed restricted. I'll compile a list of specific tools used once I finish. I'd like to hear your thoughts!