Honda EB3500X Owner's Manual page 36

Problems That May Affect Emissions
If you are aware of any of the following symptoms, have your engine
inspected and repaired by your servicing dealer.
l
Hard starting or stalling after starting.
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Rough idle.
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Misfiring or backfiring under load.
l
Afterburning (backfiring).
l
Black exhaust smoke or high fuel consumption.
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