I am having problems with my 535 virago it keeps on fouling out the back plug I have cleaned the fuel system carbs and replaced the filter but is still doing it can anyone please help Kevin

Can you post a pic of the fouled plug? If not, is there any buildup or deposits on the plug? It could be a number of things, what are the other symptoms that your bike is experiencing?

well I just put new plugs it it and it has a dark black layer of soot on the back plug. The bike is just running rough and it is making a popping noise out of the tail pipe. I just finished cleaning the carbs with chem dip and am putting it back together. can you tell me a couple of things to look for thanks for your help

Those are carbon deposits on the plugs. Dry sooty deposits indicate a rich mixture or weak ignition. Causes misfiring, hard shifting and hesitation.

Check for a clogged air element, high float level, sticky choke and worn ignition points. Use a spark plug with a longer core nose for greater anti-fouling protection.

Actually this just gave me the idea to recreate a Spark plug chart for this site. Hope that helps.