Are you sure you are only chasing one leak ?
When restoring tractors many use coolant as a gentle way of removing paint, could you also be looking at a coolant leak ?
Stuffing paper towels in gaps then looking for wet spots can help pin down a leak.
You may need the motor running to find high pressure leaks.
Don't rule out rust spots in the tank, water sits in the bottom and causes rust holes.
Some of the 19 rides in my shed
2014 V2, Snoopy
2009 Wee, Pumbaa the pig
WR450F, The Blue Postie Bike
YZ250N smoker with rego, Stinky.
Yamaha MT09 (FZ09), The Scud missile.
Club Lead not Club Med.
He with the most toys wins.
Out of my depth in a puddle.
Live life on the edge you will see more that way.
Ridding a motorcycle keeps things in balance.
At the end of each trail and at the end of each day history is made.