Hi, I have a 1985 250 rebel that has 38000+ miles. Recently head gasket started to leak oil, so I replaced it and readjusted the valves,etc. Also changed oil had about 60 miles on change before leak started, repaired cracked exhaust pipes at the mufflers and some drag holes. Put it all back together and started. Ran and sounded alot better than before. Road it about 36 miles normal riding, same power no loss of speed exhaust sounded alot better. Got home the left exhaust had turned blue with some gold mixed in. Rechecked valve adjustment all good at .003. I loosened up left exhaust valve to .004. Went for a ride around 28 miles got back home checked with laser temp gauge, left was around 130 degrees hotter than right. Can't figure want has happened to cause this. Anyone have any ideas, Thanks.