I picked up a 1983 honda CX650 some years ago that the owner gave up trying to get started every day, they even made a bigger battery tray for a bigger battery,turned out to be a combination of a dirty stator connection plug and the infamous internal starter ground. Fixed both and bike starts fine, BUT......
If you buy a new lead acid battery off the shelf and install it, start and run bike that battery will never be 100% there, has to have a couple hours trickle charge first. I found that out years ago.
It's easier to replace battery than the starter, I suggest a good name brand like the Odyssey and start over, charge it first though, don't overcharge or cook it, 2 to 5 amps for 2 to 4 hours I believe is good enough.
And yes a battery maintainer charger overnight is best, like the Battery Tender brand name, it's a smart charger, not a trickle charger which will work but the Battery Tender works better.
Btw, I have the same issue with my 85 max I bought two days ago, but it's going into winter storage today, what I said is what I would do to mine anyways.
