2006 BMW K1200 LT Battry runs flat over night,pulling 4.09amps when measured between batt and eath

You have either a starter relay or the solenoid is stuck. Since I don't know what make the starter is, that's about all I can tell you. Try putiing the bike in high gear and rolling it back and forth and turn the engine just a bit. Sometimes that "unsticks" a starter drive gear. Might work. Good Luck!

I wouldn't sweat it unless clutch is slipping. . Never heard of semi synthetic .

Chec out the owne's manual 
http://www.autosmanual.com/186/bmw-owner’s-manual-comsystem-k1200-lt-pdf.html

Thanks
Fame !