The only way to properly clean the pilot jets is a # 78 drill, anything less , spray, guitar string, wont cut it.
Clipped this from vintage bike mag.
"pilot jet can be cleaned using a #78 drill (.016″ diameter). It will have to be securely mounted in in a brass tube or equivalent. It is a confounded nuisance when the drill gets stuck in the pilot jet and comes out of the brass tube! Twirl it between your fingers in a clockwise rotation and it will draw any “swarf” down stream of the fuel flow and help prevent the drill from becoming stuck.
Yes, a guitar string can remove “swarf” from the pilot jet orifice. It doesn’t insure the jet orifice is returned to its proper size. Also the “swarf” in the jet is pushed up stream of the flow of fuel. This allows the “swarf” to flow back into the jet and potentially partially block the orifice. The guitar string technique works only if you modify the carburetor where the body is drilled and tapped to accept a modified pilot air screw opposite the working air screw. This way you can push the “swarf” down stream of the orifice. See Amal’s web site to see this modification."
The whole article is here. http://vintagebikemagazine.com/technical-articles/amal/