Fast carb cleaning. Lazy mans way.
It will most certainly not cure problems associated with really dirty carbs
but maybe the odd 'vacuum piston sticking'/'a bit of sticky build up in carbs' problem
...maybe call it the 'I haven't been riding for a while so I'll do a flush and cleaning' procedure.
(When I took the pictures a while ago, getting the bike ready for summer,
I actually thought I had an original idea, but then I realized that Randakk
describes a procedure along some of the same lines.
Never mind, here comes the pics).
Release the air filter / body.
Empty the float bowls(*)
...no; be real lazy; run the engine dry.-)
..release intakes and
'squat' intakes to the side (cover intake holes on engine):

this will enable you to squeeze the carbs down
so you have enough room over the carbs to carefully lift off the vacuum chambers.
...and to carefully remove pistons.
...keep track of witch pistons/chambers belongs in what carb!!!
..take a spray can of carb-cleaner and fill float chambers/carbs
((*) read the instructions. Some have to be mixed with fuel. Some will damage rubber parts if left too long/undeluded)

While the cleaner does what it's supposed to do
you have time to clean the vacuum chambers and pistons

I use a strong bathroom(!) cleaner. Very effective!

..and some thin soft tinfoil
Mind you: "thin"..."soft".
You don't want to scratch and sand away material...just clean.
A polish could be enough if the parts are in good shape.
removed the needle, cleaned the piston and the hollow thingy
in witch the piston slides

and
the piston 'tube'

...rinse everything in carb cleaner
Note: some types of carb cleaner will damage the
protective lacquer on the vacuum chamber tops.
...check that pistons moves abso.flipping.lutely freely and smooooooooooothly
...put everything back together
(check your manifold O-rings while you're at it)
...kill switch OFF, run the starter for a few seconds
to move the cleaner 'round carbs....let it soak for a while
...kill switch/fuel tap ON
...start engine
...lots'a smoke .-)