Radiator Fan Switch
#21
I don't know thread size.
My fan would kick on like it should on hot days, slow riding, usually up a tight single track. Then it stopped working so well. I replaced the OEM switch and it didn't seem to make a consistent difference, so I put in a switch. If you see my notes in the FAQs, I used a SPST on/off switch and not the three-way listed in the hand-drawn diagram. This way it works normally (via the OEM switch) or on. I run a TrailTech Vapor computer and watch temperatures with two separate warning temperature lamps and pay attention to temps. I'll kick the fan on during hot days when I'm riding slow single track climbs or other times when the Vapor indicates temperatures approaching 200-205F.
My fan would kick on like it should on hot days, slow riding, usually up a tight single track. Then it stopped working so well. I replaced the OEM switch and it didn't seem to make a consistent difference, so I put in a switch. If you see my notes in the FAQs, I used a SPST on/off switch and not the three-way listed in the hand-drawn diagram. This way it works normally (via the OEM switch) or on. I run a TrailTech Vapor computer and watch temperatures with two separate warning temperature lamps and pay attention to temps. I'll kick the fan on during hot days when I'm riding slow single track climbs or other times when the Vapor indicates temperatures approaching 200-205F.
There's also the issue of "heat soaking" at fan kick-in temps. It's harder to bring the temp down from those higher rates, and when you kill the engine while it's in its higher temp range, it shoots up even higher. Engines need a certain temp range to operate at the best efficiency and power output, but you can lose a little...very small...amount of power at the higher temps before engine damage levels are achieved. I have a fairly high mileage KLX with a 300 cylinder installed. Valve wear/adjustment, oil consumption rates, and other wear factors over time have shown to be almost undetectable. It's pretty much due to good maintenance and service attention, but I also believe that maintaining more moderate engine temps with a manual fan switch have contributed to this too. My KLX has been operated more like an actual off road dirt bike than a commuter/pavement bike, so it hasn't really been babied.
Some people don't want the issue of monitoring a gauge or turning on a fan, and that's fine. I don't think this is one of those mods that is required, but I do believe when properly used it's better for the overall operation and life of the engine.
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