i have a kawasaki vulcan 900. when i release the throttle i hear a popping sound coming from the area behind the air cleaner. it happens mainly when i use a small amount of throttle. when i rev it up it doesn't happen. couuld it be the air switch unit? am i harming the engine by riding it?

Don't worry about it.

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Of course I'm generalizing from a single example here, but everyone does that. At least I do.