hm.. blue smoke usually is indicative of oil..
valve seal job??
the tank is an easy off deal.
thers two bolts up front, two under the seat. take em out and lift the tank straight up.. might wanna have a buddy around to disconnect the fuel line from the petcock, which you should have turned to the "off" position...
now, with the vac and vent lines off the airbox, remove the lid to gain access to a few 8MM bolts securing the airbox to the carbs.. remove them and just lift the airbox up and off the motor to reveal the plugs.
if you need an in-depth on the carbs and their service, just PM me and i'll post a lil how-to up with pics and stupid lingo and all that stuff. hopefully the spares i have laying around the shop are the same.. they should be... (mikuni CVK's)
also, if you decide to remove the carbs or play with the linkage, you should look into syncing them.. you may want to entertain that thought even if you don't remove the rack. if they're close on the manomoeter, don't touch em..lol i had a buddy that thought he was some guru and he completely fucked my boy's CBR900RR up so bad, not even a dyno tune could fix it..
.i tried for a solidday to tune it, i got as close as a solid idle and running well at 2300rpm and up..lol we eventually just jetted it and it worked out well that way.. not sure why, but it did!
but ya.. you probably have a stuck float..
well.. actually.. that overflow line.. is it from the carbs or the tank? if its the tank, i'd try opening the tank up to see if its vaporlocked and not allowing gas into the carbs..
the pumps aren't very strong, and if the vent lines get clogged or something stupid happens, the pump isn't strong enough to fight the ensuing vacuum.
if its a carb line, then ya.. you probably have a stuck float or clogged jet or screen.