Eventually had my 280 running at the weekend but realised the fan wasn’t kicking in. Tested the fan on a 12v supply all good. Looking at  a wiring diagram, the yellow supply should come up to then thermo switch and then to the rectifier to supply the fan via the red and blue plug. The yellow supply on mine was straight into the rectifier and then out via the other yellow to the thermo switch and then earthed the other side. Is this correct or has been botched previously. I don’t seem to have a green earth either on the fan plug as in the diagrams. I’ve just purchased another rectifier as the wires were hanging by a thread on mine  but it’s the same as in the pic. 

AFAIK the ducati system had the rectifier first then the thermostat. The kokusan has the thermostat first then into the rectifier. What years your bike?

Some rectifiers had the earth in the same plug as the fan, others were seperate. The white bullet plug goes to earth and the yellow goes to your thermostat

Edited November 13, 20232 yr by faussy

Thanks Faussy I’ll have an another good look tonight. As for year I am not sure but would guess 2005 2006, the bikes bit of mix 🙄

I think the ducati was up to around 04 and from 05 on was kokusan. If your rectifier is a leonelli then its the kokusan syste, so definitely magneto -> themostat -> recitifier -> fan

It’s definitely the leonelli unit. The wiring looks a mess so I’ll check through when I get the replacement rectifier

I am also guessing the coil should be bolted to the frame? Mine was just hanging around  under the tank by the rad cap 

Yes, there should be a lug on the left of the frame underneath the tank that it bolts too. It sits beside the radiator cap