Radiator is clean, When I ride for 5 minutes or so overheat signal comes on. Fan comes on as well. Coolant is at proper level. The coolant actually starts to boil in the resovouir. Is this a problem with maybe a pump that is supposed to circulate it? Any way to properly diagnose this?

Thanks.

 

either the pump or thermostat(should have one)

 

It is my guess that both pump and thermostat are OK on his unit, because his fan thermo switch on the radiator is activating the fan to turn on. If the water pump is not working (ie due to broken rotor) or thermostat is shut closed (ie due to corrosion), hot coolant would not reach the fan switch and the fan would not come on.

I will check three easy things first before getting into more difficult jobs:
> Coolant specific gravity
> Vent spigot on the tank. Make sure it's drill through.
> Vent hose attached to the spigot. Make sure it's not clogged up.

The BF750 has a relatively hot running engine. It's normal operating temp is either at or above normal water boiling pt of 212F. It's important to keep all cooling component in their top shape.