On my first Harley I fitted a couple of lead acid batteries and it spewed acid down the breather pipe. I switched to the Harley gel battery and no more problems.
I got rid of the Harley and kept the battery

Bloody heavy though.
I have gone through a sh*t load of Chinese batteries on my diesel bike, never again!
I would like to make a capacitor battery, one day I'll get around to it, when I can find the parts cheep enough.