Project bike 2003, never had it running, owned it about a week. First issue battery wouldn't take a charge so I replaced it with a new AGM EXT15L sealed battery 220 CCA. It had a stamp on the side of the battery E4 and the sales person said that means it was manufactured 2014. Had 12.2 vdc a little low but maybe OK. Installed on bike and starter tries to come on but battery loads down to 5 or 6 volts and of course no cranking from starter motor. This is with the sparkplug removed. The sales guy said the battery should have 80 to 90% charge on it already but I plan to go ahead and charge till it has a voltage of 12.6 to 12.8. (2.1 volt per cell.) I did remove the starter from the bike but left the electrical connected and tried another start and starter motor spins freely, battery voltages drops to about 11.5 volts during this time but I did notice that the headlights did not turn off during a start attempt. I wonder if that alone would be enough to drag the battery voltage down when starting? Does anyone know what actually turns the headlight off when starting?
The 650 motor seems to turn freely with the sparkplug removed, bike in gear and rocking it forward on the tires. I can't believe the battery is the issue. This is the third one I've had in there the past two days. The first two I had issues with and later found out they had been on the shelf since 2012 auto zone. Got a refund and went to O'reilly Auto and they got one delivered from their warehouse verifying 2014 as manufacturing and checked voltage 12.2 said it probably didn't need an initial charge so I tried it with bad results but I wonder if we have some other issue going on here besides the battery?  

Id pull the starter & see how it feels. If I had any ? about it Id take it to be tested. Also, check V AT the starter & compare to battery under load.
If its different, look at connectors. The solenoid could be internally corroded & not passing the current. Feel of it. If its hot, its resistive.
Do the last stuff before the "pull the starter"..
Ohh,, yea, hot connections are resistive. Check ground on the motor, right side, near clutch. You can pull it & clean it faster than checking to see if its gettin hot,,

I'll put a good charge on the brand new battery this evening, check the battery frame connection, try it again in the morning, if I have the same issue with battery voltage dropping to 6 vdc during cranking attempt then I might try jumper cables to my truck. Battery Voltage shouldn't drop below about 9.6 - 10 vdc during cranking but its starting to look like maybe I need to disassemble the starter and clean up the commutator and service it although the starter does spin like a champ when it is more or less bench tested. Starter relay is also a possibility I guess.

I'm sure you know, but that's amps not volts.  No more than 1.5A.

These little batteries are easy to cook.

OldnSlow,

I have the same problem.  Most of my posts, I look later and there's always something wrong. I need to proofread better too.

Just didn't want the OP to get confused.