94 yz 250 fouling plugs bad
Could be fuel or oil fouling. Need to determine which first off. If it is black sooty fouling it is likely too rich also it too rich may be wet.
If oil fouling it is more likely to be much more material fouling and wet sticky material.
A wet, black and shiny deposit on plug base, electrodes and ceramic insulator tip indicates an oil fouled plug. The condition may be caused by one or more of the following: worn pistons, worn piston rings, worn valves, worn valve guides, worn valve seals, a weak battery or a faulty ignition system.
A dry, fluffy or sooty black deposit indicates an air/fuel mixture that is too rich, engine idling for excessive periods of time and/or enrichener usage for excessive periods of time.
A light brown, glassy deposit indicates an overheated plug. This condition may be accompanied by cracks in the insulator or by erosion of the electrodes and is caused by an air-fuel mixture that is too lean, a hot-running engine, valves not seating or improper ignition timing. The glassy deposit on the spark plug is a conductor when hot and may cause high-speed misfiring. A plug with eroded electrodes, heavy deposits or a cracked insulator must be replaced.
A plug with a white, yellow, tan or rusty brown powdery deposit indicates balanced combustion. Clean off spark plug deposits at regular intervals.
Sep 06, 2014 |