Have you read any of the Hi-Lited Links in my eariler postings? I just re-confirmed that all three of them operate.
A TX9 AGM battery in your KLX650 is not necessarily an undersized battery! Same size used in DR650, XR650, VFR750 V four.
The question remains, what is wrong with your bikes starting system and/or charging system?
Did you purchase that battery in a box? Dry / Un-filled & you had to charge it yourself? Or was it 'supposedly' Filled / Charged / Ready to Install from the retailer?
Either way, I have to find it questionable from 12,000 miles away.
Here is my 1st question.
What was its 'at rest' voltage before you ever put it in the bike?
What is its 'at rest' voltage one hour after charging And one hour after riding?
I've found that an AGM should be initially charged to 15.5 VDC on an old fashioned 1 amp charger for Longest/Strongest life.
Automatic Chargers / Battery Tenders / Maintainers usually turn-down Too Early to achieve the 15.5 VDC.
If an AGM is not brought up to this 15.5 volts on its initial charging, they seem to never achieve full strength & die young. Flooded cells need to be brought up to 14.5 volts for the same reason.
A 'Good' AGM should then Maintain at-least an 'at rest - 1 hr after charging' Minimum of 12.8 volts.
Will your battery pass this simple testing today? Will your battery still be very close to the 12.8 volts after 6-12 hours?
Yes, I will agree that if your charging system would maintain nearer 14.2-14.5 @ 2000-7500 rpm it would be better.
Therefore I supplied the links to threads about the new style MOSFET regulators.