A. Spark Plug wires are a critical part of the ignition system in your bike. Their job is to carry the electricity from the ignition coil to the spark plugs, where it is used to make the sparks which burn the gasoline which, in turn, makes power. If your plug wires were in poor shape your spark plugs will deliver weak sparks--causing increased emissions, poor performance, and poor gas mileage. If your plug wires are in excessivley poor shape, the engine will misfire, lug, or run rough. Problems like this ususally manifest themselves as "missing" or "chugging" at idle or misfiring and generally weak performance at the top end. Sportbikes are particularly susceptible to this becasue their high-compression engines require even more power to fire the plugs. Though you might not think so, spark plug wires undergo a lot of stress. They are exposed to the high heat of the engine, as well as vibration--which will make cheap wires fail quickly.
Q. So, is it possible that changing spark plug wires can make my bike run better?
A. Yes. A spark plug wire that is in good condition will make your bike run better compared to a poor quality or failing wire. This is becasue a good wire will transmit more of the coil's power to the spark plug. Poor wires "waste" this power due to high electrical resistance or by arcing through failing insulation. A powerful spark is important becasue stronger sparks initiate more consistently timed and more complete combustion in your engine. This means that good plug wires will make your engine produce more power while wasting less gas due to incomplete ignition or misfiring. Even if your wires are brand new, they could be costing you power if they are of substandard design.
Q. So, you're saying that the right plug wires can make more horsepower? Why?
A. Yes. Superior spark plug wires make more horsepower becasue they deliver the maximum amount of electricity from the coil to the spark plug. This, in turn, creates more powerful sparks. A powerful spark makes more power than a weak one because it ignites the fuel faster and more completely. As well, a quality spark plug wire will not generate electric interferance. Electric interferance can cause noise in the various sensors in modern computerized bikes. This noise and interferance can make the ECU mis-understand the current operating conditions of the bike--which will hurt performance severely.
Q. What makes a good wire?
A. A good wire has one main purpose: conduct electricity from the ignition coil to the spark plug. The lower the resistance of the wire, the better. However, there are several other important factors that contribute to a truly good plug wire. In addition to low resistance, a good wire must have good heat resistance properties. Since the wire will be very close (sometimes touching) the hot engine, it must be able to stand this heat without breaking down or degrading. It must also have very good electrical insulation. Since the voltage passing through a plug wire can easily exceed 30,000 volts (that is 250 times hosehould power!), it must have very good insulation so that it does not short circuit or arc to ground. The plug boot is also important. This is the rubber "end" of the wire where it fits over the spark plug. In addition to being heat resistant, this cap needs to prevent arcing around the insulator on the plug. Finally, a quality wire must control electrical interferance in some way. To summarize, a good wire must have 1) low resistance, 2) low interferance (EFI), and 3) High quality/high-heat materials.
Q. OK, so how to stock wires measure up?
A. Poorly. Simply put, stock wires aren't designed to last a long time or to deliver maximal performance. The dealership wants to sell you extra wires frequently, at high prices. In addition to having poor durability, stock wires are high resistance. This is because the easiest way of making an interferance-free wire is to make the core from a high-resistance graphite composite. The resulting wire is low interferance, but is also very poor performing.
Q. What is the best wire? Why?
A. We belive that the best wire on the market is the MSD Ignition "super conductor" 8.5mm wire. This wire is extremely popular in all forms of motorsports for good reason. It is an extremely durable wire that will last the life of your bike. The insualtion is a high grade silicone rubber--which can stand high temperatures and will not arc through. The core of the wire is braided over with fiberglass for superb mechanical strength...but the best thing about the wire is the core. The MSD Super Conductor wire core is a tightly wound spiral of solid wire. This has extremely low resistance. As well, the spiral design cancels out the electrical interferance. This wire has BOTH super-low resistance and essentially no interferance. The boots and terminals on MSD wires are also the best on the market today.
Q. That MSD wire you talk about is 8.5mm. What about these 9 and 10 mm wires I've heard about?
A. The diameter of a spark plug wire refers to the diameter of the insulating jacket. It has NOTHING to do with performance.
Q. The MSD wire you recommend has a spiral core. What about wires with a straight wire core?
A. Straight wires will have slightly lower resistance (fraction of a percent) than the MSD wire. However, these wires are acutally WORSE for performance. While you might gain a very, very, small power gain from the slightly lower DC resistance, you will LOOSE power from the extremely high interferance found in a straight wire. The MSD Super Conductor wires are superior becasue of their synergistic combination of low resistance and low interferance. As well, we know of no straight wire that has anywhere close to the durability and arc-over reistance that the MSD wires have.
