Electric Fan Conversion Justification

If your bike has a mechanical fan, you may be wondering why conversion to an electric fan is even worth considering. After all, it sounds like a lot of work and it's been fine for all these years, right?

Electric fans have a number of advantages over the stock mechanical fans, improved efficiency being one that immediately comes to mind. But a compelling reason to upgrade is the tendency of the mechanical fans to develop stress cracks. When this happens the fan can come loose on its metal hub and make a lot of noise. It can also become misaligned and come into contact with the radiator, destroying the radiator in the process.

Several CX/GL Forum members have experienced this firsthand. Forum member AZ_CX500 has shared this example of a fan failure.


From one of my own bikes, stress cracks are obvious in this original mechanical fan, now over thirty years old.


Unfortunately, new fans are also prone to stress cracks. The fan in this photo is only a few years old and has less than 500 miles on it; severe stress cracks are already evident. Judging from the original packaging, the fan was not old stock but had been recently manufactured. This is not an isolated instance, either, as several forum members have also reported stress cracks with new fans. Nor is it a case of improper installation, as this fan was carefully installed and torque values were adhered to in strict compliance with the factory service manual. Honda simply seems to have a quality issue with their replacement fans.

Often a mechanical fan will make a "tock-tock" sound after it has developed stress cracks.

Even if you are not considering an electric fan upgrade it would be wise to check for stress cracks. When doing so it is important to inspect the rear of the fan, as the cracks are not usually visible from the front.

Electric Fan Conversion Justification 500 only
Tachometer Cable Screw Replacement 500 and 650
Electric Fan Selection and Mounting 500 only
Camshaft Clearance Considerations 500 only
Fan Power Relay 500 and 650
500 Radiator Temperature Switch 500 only
650 Radiator Temperature Switch 650 only
Fan Always-On Modification 500 and 650

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