I started my bike today and heard a faint clattering sound - quickly chased it to the shield on the silencer. One of the three hex-head screws securing it was gone. I went to the hardware store with allen wrench in hand (pocket, actually), and removed a second screw to find a match. It came out with little difficulty, with threads slightly surface-rusty but otherwise intact. The shortest replacement I could find was just a hair longer than the original.
I put both back on the bike (they both went on fairly easily), and sure enough, the longer screw bottomed out just before the head clamped down on the shield. I thought I'd grab a washer to fill the gap, but... darned if I could get either screw back out again. After I got home, I waited for things to cool down a bit, then went after both screws with penetrating oil, all the while thinking I was going to strip the hex socket or break the tool (not likely to break the head off the 6mm screw). I eventually got them both out, with threads intact, but what the heck is going on here? I was going to lock-tite them, but now everything is saturated with penetrating oil. Anyway, I don't see how they would have come out on their own as tight as they were.
Ideas?
Will residual penetrating oil bother blue lock-tite? Will blue lock-tite work at all with the heat of the exhaust?