Popping and Backfiring

By Dennis Santopietro

Q: Hi I am Having Problems with my 73 Superglide!! Bike runs good when idling as soon as I take it for a ride it starts popping and backfiring!! Dies out then I wait a couple seconds starts up then does the same thing over again!! Starting to get Frustrated!! Hope you Can Help!! Tried taking the carb off and cleaning it still does the same thing changed the points, plugs, coil!! Hope you can Help!! Thnxs!! Eric!!

A:Eric, Start with testing your charging system. Make sure the system is not over charging. That bike probably should not give you a reading above 13 volts dc (depends on weather you are running a 22 or 32 amp system). If that’s o.k. check for an intake leak. While the bike is idling, mist the intake area with brake cleaner. If the idle changes or the bike stalls, you have a leak. You will need to replace the intake clamps and seals.

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13 Responses to “Popping and Backfiring”

  1. craze

    replace the condenser... start w/ least expensive fix first...... and your problem sounds like exactly what a bad condenser will do.......... for real...... been there, done that... twice

  2. Gary Glass

    Restoring a 78 superglide, how long should vent hoses be ?

  3. DALE LANTZ

    My 2001 super glide does the same thing. Any suggestions?

  4. Richard Butler

    Could be the timing advance. Check the weights and springs behind the points plate. My 73 had that problem once.

  5. Daniel Sears

    I agree with all the others, you start at the carb and work your way down but do check the timing and most important check your valve adjustment. If you have a weak valve spring it might not be closing completely at a higher RPM . Good luck. Ride upright.

  6. Rick

    Check your coil. I had a simular problem with a 02 fatboy. Changed the coil and problem solved

  7. Stephanie

    Does sound like an intake leak. When checking for an intake leak, use WD-40 instead of brake cleaner (brake cleaner is so volatile that even a tiny bit of stray mist going into the air cleaner will give you a false reading.) Be sure to spray from the right side of the bike onto the seals, again to prevent anything going into the intake. Intake leaks were extremely common with shovelheads...the ignition switch could also be an easy culprit; if it's not the dash-mounted style it could just be getting worn internally (jiggle the key) or contacting something behind the switch.

  8. Luc

    Replace the air filter, samething happened To me and my friend and it was the air filter in both cases.

  9. Gerry

    You could have a lean air fuel mixture

  10. Danny

    I’d try a known good coil just to eliminate that as a possibility