Sounds like you have a pilot
circuit stopped up from the old gas. You're probably going to have to get the carb
apart and clean the pilot with a needle or wire if it's totally stopped up.
After sitting for 2 months with the crap gasoline that is sold these days my wifes bike (VStar 650) would hardly start and then would only idle. It would also rev
if I could jump past the pilot circuit. I had forgotten to dose her fuel with Seafoam and Startron as I always do. I took the carbs apart and found that both pilot jets were clogged with the hardened sludge caused by the alcohol in the fuel absorbing water. Once that crap stops up a passage you can't just dump Seafoam in and expect it to chisel it out. I actually had to order new pilots for her carbs.
The way I have gotten used to doing the fuel in my bikes and the fuel that I buy for all of my small engines is to keep a half dose in them always. And I use Seafoam AND Startron together. Seafoam is better for cleaning the inside of the carb and the carbon from the engine and Startron breaks up the alcohol and water it absorbs so it passes through the fuel system better. Some will probably disagree but I don't have starting and running problems with my small engines anymore and I haven't had to disassemble any of their carbs since I started doing this.