My bike battery is no longer capable of cranking the engine if it doesn't fire up after 2 or 3 attempts. This arvo after work, I had to roll start it to fire it up and I also took a moment to run a digital meter across the terminals while it was idling. I got 12.5v. It should be at least 13.5v and above, much like a car battery but no amount of revving produced an increase in the voltage so I'm thinking it's no longer recharging the battery properly. My question is; what does a regulator / rectifier cost for a GPX? A few bucks? Or am I giving up lunch for a week to pay for it?