Honda Shadow Backfire/Afterfire on Deceleration? – DIAGNOSIS

First of all let's clarify something:

- Backfire is combustion, sneezing, coughing or spitting out of the carb. 

- Afterfire is loud popping or rattling out of the exhaust -- so we're going to tackle "afterfire" first:

If your bike is afterfiring, your pilot circuit is too lean or you have a vacuum leak. Start by adjusting your air fuel mixture screw(s). If that doesn't fix the problem, you may need to go up a size on your pilot jet or find the source of your vacuum leak

This issue could also be indicative of an exhaust leak, or a valve being out of adjustment spec (rare).

If your carb is coughing, that's also an indication of a lean condition. TJ gives more details in this video:

Does your bike need a little rejetting? Get the tuning kit for your bike HERE! -