If the battery is bulging on the sides then I believe its called being sulphated and its toast. If you want to try and recharge it I think your best plan is to hit it with about a 10 amp charge for a short while, not overcharging it. But as a sailor/boater and a guy who has really dealt with batteries in everyday life a lot... The best place to call is Polar Battery on Boundary Road. I've had more than one battery issue where the guy brings out his fancy little machine and tells me in no uncertain terms, your battery is fine I won't sell you one, just go home and charge the ($($(#(# out of it and it will be fine. And he could have sold me a $75 battery.
There number is 294-1891. Or just take it over there. They have great prices to begin with but they'll probably even give you a BC Sport Bike Discount if your nice.