It seems that the spark plug coils are draining my new battery down. Even when I disconnect everything else. This is before the bike is started. Haven’t gotten that far yet. Soon.
Are you sure its the coils? I would guess that maybe the regulator is stuck and putting a charge back through the generator/starter.
I’ll check. Can it be done with a simple volt/ohm meter? I think the manual has a procedure. Are they repairable? (I have a hammer and vise grips)!
The manual I found this morning has alot of testing procedures in the electrical section https://2fiftycc.com/index.php?resources/yamaha-yds3-service-manual.297/