Dear Mr. Know-It-All,

My 2022 Beta Evo 250 trials bike is having fan woes. It kicks on and runs fairly normal until about 30 minutes into riding. The fan starts surging and pulsing, then goes back to normal. The fan spins freely and nothing is disconnected. What could be the culprit?

Ron Rollins

via [email protected]

While I have not experienced such drama, I checked with my balancing friends for a clue as to your issues. Underneath the rear fender near the airbox, both the fan and thermal sensor plug into the machine’s main harness. Check these two points of contact for a loose connection or debris, such as dirt or corrosion. If those two items check out, turn to the thermal sensor. This is located on the bottom-right corner of the radiator, and this sensor tells the fan when to run and what temperature to turn on at. If the sensor is starting to fail, it will cause the fan to be extremely confused in terms of when to run, therefore possibly causing the surging and intermittent running.

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Dirt Bike P.O. Box 957
Valencia, CA 91380-9057

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