Grabbed it for cheap at Walmart, I think it's called everstart or whatever the cheap brand is. I'll grab the part number off the battery for you. Its just a lawn and garden lead acid battery, nothing special. I have it on one of my karts, but it's probably a little too big and bulky for a bike. I would look at one of the sealed gel batteries, they're much smaller. Walmart also had those in 18AH but it cost twice as much.