I took my FZ6 to the dealership for them to install a new Pirelli Diablo rear tire. The OEM Dunlop was so square it looked like it belonged to a Buick. I noticed a couple of things riding back home. First, I could hear a hum coming from the gearbox area (chain too tight?), and that the clunkiness of the gearbox was gone (especially 1st to 2nd shifting). I went home and loosened the chain to specification (1.77 inch, tightest). The hum was almost gone, but the bike shifted like crap again. I did searches about chain slack adjustment and got very good info, but I have a couple of questions: How much pressure do you put on the chain in order to measure slack? I can almost touch the swingarm if I apply enough pressure with my fingers. Does having a slightly loose chain shorten the life of the gearbox?