I never charge a motorcycle battery at more than 1 amp. You can safely leave it on a 1 amp charger for 24 hours. As someone said, not all batteries work right with those battery maintainers. But if the battery is charged, or has been on the charger long enough, and still won't start the bike, there is a problem. If you can jumpstart the bike, then the battery is bad.
2002 Vulcan 750, 2001 XT225
2008 Vino 125, 2009 Genuine Stella
2012 Zuma 125, 1980 Puch Newport moped