If it's a factory-installed sealed battery, charge it at 10 amps for 1 hour or charge it at 2 amps for 5 to 10 hours. If in doubt, use an automatic charger. For even better results, keep the bike on...
Remove from the mc, disconnecting the ground cable first. Then hook up to a trickle charger at 10% the amp hour rating of the battery. Probably 2 amp. Charge fully, overnight is a good bet. Then load...
I just replaced a Harley battery with a YUASA, YTX20L-BS. It has the same construction, AGM, as the original, Harley battery. The charging information was on the top of the battery. It specified...