I didn't realize that you had compressed air available.
Steve can better answer this, but I would start at 10-20 PSI.
Also do the Tap, tap...... Try to dislodge a piece of trash that may be under a needle seat.
NOTE: The important thing Steve said was "open all bowl vents".
In other words, drain all the carbs before doing this, and leave the valves open...
This will open the needle valves, and prevent possible damage to the diaphrams.
Ride safe, Ted
PS: There is one other way to dislodge trash. (believe it or not,,,, An old lawnmower mechanic told me about this).
You can use something like a Turkey Baster and push/pull gas in and out of the carbs with the valves open. The surging gas will dislodge trash...
BUT,, be aware that your splashing around a lot of flamable gas!!!!