Quote Originally Posted by rxcrider View Post
Check the rubber iso-mounts at the front of the muffler. I've never ridden with them dmaged to know what it would sound like, but when I was disassembling my bikes to build one the first time, I found one of the mufflers had both iso-mounts torn in two and the mounting hardware was loose.
rxcrider was right. On my homeward commute tonight, I picked up a Mobil 1 M1-102 oil filter and a couple of liters for replacement. New filter didn't fix the noise, so further inspection found the rubber grommet (# 34321234629), holding the weight of the exhaust, working itself out of it's bracket. Apparently when new, it's held in by a circlip (# 07129934330), which is now missing. I reseated the grommet between the bracket and the exhaust holding arm. It was quiet around the block. Nice!

I'm going to order both pieces tomorrow.