I have an 88 K75 and I recently installed a new Acewell speedo/tach hooked up to a BEP. The Acewell has an oil temp bulb, but no coolant bulb. After going for a long-ish ride that was freeway/twisties and getting back into the city, I sat in traffic and had the bike overheat with steam coming out of the nipple on the coolant reservoir on the right side. I immediately shut it down and let the bike cool down. I've since gone on a couple more rides and even when the bike heats up, the fan doesn't seem to ever come on.

Does the lack of a coolant bulb prevent the circuit for the fan from kicking in/turning on? If not, what's the best way to diagnose the fan not kicking on?

Cheers

Have you tried rotating the fan with a dowel or screwdriver to determine if it's seized? It should move easily with prodding. The fan on my moto was seized when I bought it. The lack of an overheat indicator bulb should not stop the fan from working. In a correctly functioning system, the fan starts before the overheat bulb lights.

If it's an OEM fan, it's probably skunk poo by now. If you can reach in behind the fan, the motor housing will click off with a bit of wriggling. Take a look at the brushes and springs: chances are that they are defunct. If so, forget getting a new fan. Just run a search for SPAL on this site.