So I'm not sure if this is known yet, or if it will even help, I've found a glitch involving any bike while at the starting line.

If you keep tilting the analog stick over (I'm using a GCN Controller), your bike will actually move the direction you keep tilting the analog stick in.  You can pretty much start anywhere on the line within about 1 or 2 bike-lengths away from where you normally start.  This might help increase a time by about .1 seconds, if that.  But nevertheless, this seems like a fun trick.