Suzuki Boulevard C50, cranks but won't turn over to start. It has not been used much recently though short ride was taken a week or two prior to this problem. Battery seems charged sufficiently and gets to the point that it sounds like it will start but just never accomplishes it. Before this happened, had used fuel injector additive because it started acting like that could be an issue. New problem started about 2 mo. after using the additive.

Instead of taking the tank off just drain the gas tank and clean it like that get all that gunk out of there, also check the starter solenoid, i have an LS650 S40 Boulevard. i had the same problem, i let the bike sit up and the solenoid seized. i don't know if this helps any, hope so. most of the most annoying problems can be so simple to fix

Fuel does not have a very good shelf life. it only takes a couple of weeks to lose it's octane level. although fuel injector additive is good to clean and maintain your fuel system, it is not a fuel stabilizer to maintain octane rating in fuel. i recommend changing you plugs and draining your old gas and replacing it with fresh gas. try using a product called SeaFoam in your fuel, it cleans and stabilizes, you can get it at your local auto parts store.