1984 VF500 fan problem

The fan on my 84 VF 500 won't turn on. I have replaced the fan switch with a brand new oem switch. When I jumper the wires, it turns on. The thermostat appears to be opening. I'm stumped.

 

The stock thermo switch has a pretty high temp threshold. How far up the temp gauge have you let it go for testing.

I also wire in a parallel toggle switch so I can turn the fan on when I want to, but leave the original circuit in place.

 

I let the gage needle go to vertical which is slightly past the normal range.

 

That's not far enough on a 500. It will be 3/4 to "H" or more.

 

You were right, it did turn on when the temp got hotter. I wired it for a switch. Going to find one with an power on light this week. Thanks.

 

It's OK to have high coolant-temps, as it was designed. Delta-D between combustion-chamber and water-jacket determines A LOT about efficiency and power. Too-low coolant-temps will suck heat away from combustion-chamber and lower pressure of gases. Which lowers force pushing down on pistons and lowers power. Want to keep as much heat in combustion-chamber as possible. Thus ceramic coatings on pistons and valves of newer bikes.

Honda's been working on ceramic-based engines with no coolant, runs super-hot for higher-efficiency and power.