hey guys, just came across this forum while attempting to google stuff for my 250gs.  I bought it in June of 2010.  its an 06 model with only 1700 miles.  rode it just a little last year, and maybe 4-500 miles this year.  have had some of the battery problems mentioned in other posts, but nothing undoable.  however, i recently ran into a whole new problem.  as I was driving to work, I accelerated from a stop, but as I went to change gears, it hung up on me and then shifted really hard.  afterwards there was no power when i shifted.  it still ran and still shifted but there was no decent acceleration.  took about 2 miles to get up to 50 mph.  any thoughts?  also, was poking around the engine and it seems my chain may be loose.  could this be my problem?  either way, how do i tighten it?