BMW k1100lt fan coming on for no reason?

[rumpelstiltskin]

Just bought an old bmw k1100lt touring bike.after running for about 15 minutes out on the road the fan will come on,not at standstill in traffic,just driving normally.Temp gauge is bang in the middle of the gauge.Here's the really confusing bit,even when i disconnect the two temp sensors on the water pump the fan will still come on??and the thing is when the fan comes on it doesn't go off!Could it be a relay problem?

[LiquidGnome]

I had the same problem on my old Ninja. Turned out to be the relay if I remember correctly. It's worth checking.