What size is a NGK Spark Plug?

The first letter of the NGK spark plug code (in this case a “D”) indicates the thread size of the spark plug. There are three spark plug thread sizes currently being used in motorcycles and ATVs. “B” indicates a 14 mm x 1.25 pitch size, “D” indicates a 12 mm x 1.25 size and “C” indicates a 10 mm x 1.0 size.

Does spark plug size matter?

Not all plugs are the same size. If a spark plug is too long, it can protrude into the combustion chamber and hit the piston or a valve. A spark plug that is too short will cause your engine to buck. The spark won’t ignite your fuel correctly and can cause poor gas mileage, plus prompt your check engine lights.

Are NGK leads good?

Manufactured with advanced insulating material, NGK ignition leads have exceptional long-life durability with phenomenally low resistance values and top-of-class conductivity. NGK ignition leads come in sets, and where necessary include the coil-to-distributor.

What are the best spark plug leads?

Here are the top spark plug wires you should consider.

NGK Spark Plug Wire Set. This spark plug wire comes with variable pitch winding and an ultra-low resistance level to provide a powerful and efficient spark to your spark plugs.
Denso Spark Plug Wire Set.
ACDelco Professional Spark Plug Wire Set.

Can spark plug wires increase horsepower?

In short, yes, in some situations spark plugs can increase horsepower. The theory behind spark plugs increasing horsepower is that by providing more spark to the firing tip of the spark plug, it will (and does) combust more fuel.

What happens when spark plug wires are too close together?

Spacing spark plug wires too close or parallel to each other can also result in crossfiring due to the inductive field which builds up in one wire as the current flows in the other. Good spark plug terminals are made with a snap ring that give a metallic “click” or “snap” when they are properly set into place.