Popping and Backfiring

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.
Discussion
  • (will not be published)

14 Responses to “Popping and Backfiring”
    • ROBERT COULMAN

      That’s what I thought-if anything maybe coil heating up-Sounded like an intake leak to me right from the get-go.

      Reply
    • ROBERT COULMAN

      Also should have done a simple coil test with meter in ohms mode, isolated, as in no plug wires or anything, coil removed from bike-could have saved a few pennies on the new coil.

      Reply
  2. roy14103

    check your ignition switch sound like a short somewhere if you have fatbob tanks take counsel off and check that everything is tight

    Reply
    • Louie

      I had a similar problem. Anything over 50, bike would pop, backfire and die. Idle was fine, upon a rev in idle fine. But under power and pushing it, it would die. It was a bad fuel petcock and collapsed screen. Check that out.

      Reply
  3. Don Ellwood

    If it runs good at idle and when you increase revs causing it to bark, sounds like your timing is out, bad coil or fuel issue..Try another coil. Check the carb again.

    Reply
  6. Luc

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

    Reply
  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.

    Reply
  8. Rick

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

    Reply
  9. 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.

    Reply
  10. Richard Butler

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

    Reply