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Help me diagnose this popping sound---with video

  • Thread starter Thread starter pjm204
  • Start date Start date
almarconi said:
I think if you had an exhaust leak you would be able to hear it. Adjust the valves and sync the carbs before drawing anymore conclusions.
Click to expand...

Not necessarily.

I had absolutely no idea I had a bad gasket when I was trying to fix the Ninja. It didn't sound like an exhaust leak at all...at least, not like any exhaust leak that I've ever heard.

What it was doing was sucking air in through a very small opening whenever the throttle plates were slamming shut. That air was then combusting in the exhaust causing the popping sound. It would do it primarily when decelerating, but sometimes would do it at idle and just off idle.

It's a phenomenon that's LIKE backfiring...only the opposite. I BELIEVE that the correct term for it is "afterfire."

But, if there's new gaskets in there, it's probably not the case. I was just throwing it out there as another option to check.
 
What it was doing was sucking air in through a very small opening whenever the throttle plates were slamming shut. That air was then combusting in the exhaust causing the popping sound. It would do it primarily when decelerating, but sometimes would do it at idle and just off idle.

It's a phenomenon that's LIKE backfiring...only the opposite. I BELIEVE that the correct term for it is "afterfire."
Click to expand...

What you are describing is usually caused by incorrect valve or ignition timing. If the pilot circuit were lean that could also cause popping but I don't think that is the case here.
 
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