Looks like you have room to mount Two if you spaced them right.
Is that true?
I also found this link that someone is suggesting you should have 20deg or more drop across the radiator (coolant temp) and if you have a 180deg thermostat, you want a outlet temp of no more than about 170deg.
So if our fans turn on somewhere near 170deg outlet temp, it should be just fine.
(call it 77c )
The BWD fan switch for the '83 Honda Civic fits in the radiator just fine, but the stock thermostat for that car is a 195f, and the switch turns on the fan at 198f and off at 188f.
that would put your engine temp at about 220-225f when the fan comes on.
Not to hot for most motors I have run, but about 20-30 deg hotter than designed on a GL650.
Anybody have a loose 650 fan switch they could check the "on" and "off" temp on?
I tried my old one, and got a 350ohm resistance "on" at 180deg. that temp would work fine.
but then it failed 3 min later and now doesn't work at all. always open. so I don't know how it is Suppose to work. lol