.....Over four years later: I had the same "no fan" issue as Bigus and his Rev3 (2004) with the same bike and year. No fan either through the thermo switch, or from jumping the switch wires for me too. This is a new bike to me so not sure what was going on. Tore down front end and removed the fan. It ran fine with power directly applied, so started digging into the wiring. Previous owner had disconnected the lighting and taped over the wires (ok). Then I spotted it. SAME exact dumb "custom splicing" as above! They connected the kill switch ground (blk) wire directly to the yellow DC feed from the magneto. Why was this done on both my and Bigus's Rev 3's? Doesn't make sense at all. I reconnected yellow to yellow and ran the kill ground wire to a suitable spot with the coil ground and the fan now works. Amazing.
