ORIGINAL: Mr Electric
this is the very short version
drawing rite blue wire not a switch both motors do run
battery big enough
must get the neg feed from servo wire not reds left in esc 's
the end
I'm not sure what you said but I agree with vmsguy. Your drawing if correct should only allow one motor to run. The left disconnected motor should not get any power thru the Rx. lead that would allow it to run. Please check your wiring again and confirm that your drawing is correct. Are both motors running the same? Is the throttle responding correctly, ie; do they power up all the way? Are all the other controls functioning properly? Is the equipment new or has it been in a crash? Are you positive your not shorted out somehow someway?
BTW, Nice looking B-25. Hope we can get it figured out for you.
Standing By,
SJ