The Honda GVC160 5.5 on my lawnmower runs rough, blows black smoke and fouls the plug (heavy black soot). It also burns fuel very fast. I assume it is running rich but don't know how to adjust the mixture. Any other possibilities?
Have a look at the air filter for blockages & clean if blocked with grass, careful not to get grass in the inlet.
If this doesn't do the trick change filter as a blocked filter will cause the engine to be running rich.Take care in fitting it correctly so not to damage the filter corrogations when you refit the access cover - put this on the correct way up.
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