lead acid batteries need to be recharged immediately after they are discharged.
That is why they work so well in cars, they can sit for weeks or a few months and hold their energy, then you whack them down with 500A for several seconds to start the engine, and the alternator recharges them immediately.
Car and motorcycle batteries are designed with their chemistry optimized for that type of usage. Unfortunately one of the tradeoffs is if the battery is discharged and left for days or weeks without being recharged, there is a layer that forms on the lead plates, and its not reversible.
Dio is correct, you might be able to get some life back out of it, if its put on a bigger charger - like 10A maybe, for a couple hours, but it will not be rigth, In fact I would be surprised if it was able to spin the starter. You might be able to charge it up and push start the bike till you get a new one.
I got my last 650 battery online for about $25, with free shipping. That was 3 years ago now and the bike still starts on the first revolution of the crankshaft. That's less than it costs to fill the gas tank on your car - just get a new one, the first time you are not left stranded somewhere it will be worth it.
BTW, if you ever need a battery that you will keep charged and use for emergency lighting, or if you have a solar panel on your roof that runs a light in the house, don't get a car battery or a motorcycle battery, get a deep cycle battery like they use on boats for lighting overnight, or a UPS battery like they use to backup computer systems. Instead of being designed to surge out 500A for a few minutes, they are designed to supply a steady 10 or 20A for a few hours. But then you still have to recharge those within a day or so.
Last edited by KCW; 04-17-2018 at 07:13 PM.