How to lube Carb diaphram?

I have a stuck vacuum piston in my motorcycle's carb which is causing only one cylinder to run.



When I pulled apart the carb and cleaned it (yes I removed all rubber/plastic parts), I noticed this piston was stuck. I smeared what lube was left on it around and tried to coat it, but it didn't work.



What type of lube am I supposed to use on this?



Can I just remove the air intake and spray some WD40 or spray lube down onto the piston and work it around without removing the carbs again?



Thanks!



Specs:

1998 Honda Shadow vt1100



Heres the diagram link (Carb Comp.): http://www.bikebandit.com/houseofmotorcy鈥?/a>



I'm talking about part #16 in that diagram.How to lube Carb diaphram?
Sorry to say but you are going to have to pull the carby off again. The slide is stuck due to fuel residue inside the cylinder and no amount of lubricant will remove it.

You have to get some very fine wet and dry emery (800 to 1200 grade and dont use water)) and clean the cylinder wall and the outside of the piston. After that, you can also rub the piston with a pencil (the graphite in the lead is an excellent dry lubricant). You may as well do both carbs while you are at it.

Be VERY careful when touching the diaphram attached to the carb slide. They are very thin and the tiniest hole will stop the slide moving correctly.