Backfiring through the exhaust

PTmowerMech

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Here's the video. I'm not touching the throttle. The RPM's went down on their own. A few seconds later, they came back up.

 

Auto Doc's

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Hello PTmowerMec,

In the video, that sounds like a coil breaking down issue. You would need 2 adjustable air gap spark testers between the plug tips and the coil plug wires. Run the engine while watching the spark jump the gap on each tester.

One coil will spark continuously while the other breaks down and comes and goes intermittently.

The V-twin engines don't shake and rock as people would expect because they are mounted solid.
 
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