Harley-Davidson Dyna Low Rider Recalled for Resonance

08/04/2014 @ 12:38 pm, by Jensen Beeler9 COMMENTS


The following is perhaps one of the more interesting recalls to come across our desk, and it affects the 2014 Harley-Davidson Dyna Low Rider. It seems that if owners install “certain optional performance electronic control module calibrations” the bike’s ignition switch can go from “IGN” to “ACC”, thus causing the motorcycle to shutoff mid-operation.

The reason for this though is because the aftermarket ECU upgrade allows the 2014 Harley-Davidson Dyna Low Rider to rev its motor beyond the stock 5,600 rpm redline, where at 5,800 rpm a resonate frequency with the ignition switch occurs. Held at this frequency, the key can turn to the accessories position — a dangerous, if not fascinating, show of physics.

To remedy the situation, Harley-Davidson will notify affected owners, and Harley-Davidson dealers will replace the engine mount bracket assembly and ignition switch knob, free of charge. The recall is expected to begin by the end of July 2014.

The recall affects 3,361 FXDL motorcycles. Concerned owners may contact Harley-Davidson customer service at 1-800-258-2464; and as always, the NHTSA is also available at 1-888-327-4236 and safercar.gov.

Source: NHTSA

  • Mike

    Woah, 5800 rpm? That’s just crazy talk. If we were meant to rev that high we would have been born with naturally balanced engines.

  • indymoto

    Always pay attention to your modals. Come on HD, are you losing it? Reorganizing engineering 3-4x in as many years was such a good idea…

  • Xan

    Is it just me or….. Are they telling us they hit the brown note?!

  • irksome

    I would love to hear a shop manager explain harmonic resonance to a guy in a pirate costume.

    “Can’t I just put a straight pipe on it?”

  • irksome

    And thank you, Mike^. Best laugh I had all day.

  • “Woah, 5800 rpm? That’s just crazy talk.”


  • gm

    Srs qu3stion: How can an ecu upgrade increase the redline RPM? My very ignorant understanding of engines lead me to believe that redline would be set by mechanical limitations (valve train, connecting rods, etc).

  • “How can an ecu upgrade increase the redline RPM?”

    The ECU controls the ignition timing and handles electronic rev limiting. You’re correct that there are mechanical limitations for maximum RPM, but the electronics are generally configured to ensure that the ECU limits the revs before the mechanical limits are reached. Changing ECU settings can, therefore, increase or decrease the rev limit for engine operation.

  • John D’Orazio

    Let’s talk about that 5800 rpm for just a minute. The issue is not revs, it is piston speed. With the length of the stroke in the Harley Davidson being what it is, the piston has to travel a whole lot further up and down to complete one revolution of the crankshaft than an “oversquare” engine sport bike does. Thus, at 5800 rpm, the Harley piston is travelling as fast (or nearly so) as the short stroke sport bike engine. Of course, a short stroke allows engines to rev higher, thus producing more horsepower at those higher levels. The price, though is the sacrifice of low end horsepower and torque. That lower end power is what you need to get a big cruiser laden with heavy folks in pirate costumes moving. Like a laden semi tractor trailer vs. a corvette. Just engineering…