So...
This project has been on the sidelines while I was busy building a Sprinter van for traveling. I figured I would get started on it here in the spring but it may have to wait a little bit longer. So I decided I should at least get the S40 running again.
The bike has sat for almost two years. I had run the carb dry, popped off the gas cap, stuffed a rag in the filler hole bung (to reduce condensation in the tank), and parked it.
The AMG battery wouldn't take a charge so I replaced it. The bike would fire on a shot of starting fluid but wouldn't fire on gas. Tank was clean with a half tank of fresh gas.
I removed the fuel line and tested the petcock on PRI and RES. Nothing. I had a raptor petcock that I had planned on installing in the GS450 tank (but it didn't fit) so I tossed that on there and it fired right up and ran perfect.
I'm pretty sure my carb was supposed to disintegrate after a few months of sitting. Not sure what went wrong. haha