Personal watercraft in particular, but also offroad motorcycles and ATVs, employ resistor technology to cope with this proximity RFI issue. The CDI boxes or igniters on these machines are mounted close to the ignition coils, and therefore need RFI protection. Third, also on offroad vehicles, resistive technology is used to reduce RFI-related malfunctions of ignition control modules that are close enough to the ignition coil to be subject to these strong, nearby radio waves. Motocross bikes use resistive secondaries to protect the CDI boxes. This unwanted electrical feedback is harmful to the parts that drive the ignition system, particularly the ignition control modules (CDI boxes, igniters). Second, on some offroad vehicles, resistive secondary components of a slightly different specification are present to reduce the electrical backlash that spark creates in the coil’s primary winding. The Effect of Electrical Backlash on Ignition Components
In other words, the resistor plugs, wires, or caps are there to control electrical emissions that would otherwise interfere with radio and TV reception. To begin with, on virtually all machines, the aforementioned RFI suppression for the sake of preserving electronic communications is the goal. There are four different applications of resistive technology on powersports vehicles. However, not all vehicles use resistive ignition secondary components for the same reason. The note is the same, the vibration and tone are different. This damping is much like the muting of a tone on a guitar string with your finger on the string at the fret. Adding a carefully-chosen resistor to the ignition system’s secondary winding dampens the spark’s electrical noise, with little effect on plug voltage, since there is a surplus of unused voltage at the coil anyway. RFI can also interfere with other electrical components on the vehicle, particularly the more sensitive solid-date electronics. The second problem, and one less known, is that an ignition system’s electrical noise also creates an electrical backlash in the ignition system that unchecked can interfere with the system’s integrity. This radio frequency interference (RFI) intrudes on electronic communications to the point that it can cause Jay Leno to stand on his head on your neighbor’s TV! You can imagine the difficulty with emergency and law enforcement communications. First, it creates electrical emissions that coincide with radio transmission wavelengths. The electrical noise presents two problems. However, this high-voltage release is very messy (electronics techs call it electrically "noisy"), that is, it crackles and pops. Because the windings vary considerably in size, this voltage is stepped up tremendously into the thousands of volts necessary to fire the spark plug. The primary winding, depending on the system, is either turned on or off, and the resulting appearance or loss of magnetism induces voltage in the secondary winding. It has two electrical windings, that is, a primary winding and a secondary winding. The What and Why of Resistive Ignition ComponentsĪn ignition coil is a transformer.
Just what are resistive ignition components for, and why do we need them? Many have more than one of these things, and a few have all three. Most powersports vehicles (motorcycles, ATVs, personal watercraft, snowmobiles, scooters, and utility vehicles) come with resistor spark plugs, resistive spark plug wire, or resistor spark plug caps. Resistor Plugs, Wires, and Related Issues Resistor Plugs, Wires, and Related Issues ®