Issue link: https://read.dmtmag.com/i/714189
77 www.thunderpress.net THUNDER PRESS nSeptember 2016n when covered in water or muck. Hall effect has become the overwhelming choice as sensor technology evolves into crank angle sensors. These typ- ically are placed to read the starter gear teeth on the fl ywheel providing the high degree of positional accuracy required for advanced engine manage- ment systems. Hall effect sensors are also widely used to sense wheel spin for traction control and on anti-lock brake systems. Coiled up Let's talk voltage fi rst, since this is the main entrance for most people's trip down the garden path. That hot- rod, hi-perf 60,000-volt coil you lust after is more than likely useless over- kill! See, once the voltage has built up high enough to jump the plug gap, its job is basically done. After the plug fi res, the voltage required to sustain the spark is much lower. Regardless of air-to-fuel ratios, plug gaps or most any other things associated, you'll never need more than about 17,000 volts to initiate combustion. But… three important terms to keep in mind: Secondary available voltage, required fi ring voltage, and reserve voltage. Secondary available voltage is what the secondary side (or high-voltage side) of the coil is capable of producing—say 30Kv. Required fi ring voltage is what it actually takes to jump the plug gap— perhaps 14Kv. Reserve voltage is the difference between the available and required voltage—16Kv (i.e., what's left over). So what good is this reserve voltage? Well, as the spark plugs begin to wear and lose the sharp edges on the electrodes, the required fi ring voltage may go up by 1 or 2Kv. Inspect your plugs and wires lately? Burned or broken conductors, cracked wires, and the like may require an addition 3 to 4Kv to overcome the additional gap. A 30Kv coil is an insurance policy… no more, no less. Getting wired The three most common spark plug wire types are metal core, resistor core and spiral core. Metal core wires consist of stranded copper or stain- less steel conductors. Resistor core is generally constructed with a fi lament impregnated with carbon or graph- ite particles, and looks like a pencil lead. Spiral core looks very similar to resistor core, but has a very fi ne wire wrapped spirally around the core. Metal core wires for the most part are obsolete due to the interference they generate with other devices and systems… like radios. However, they are still found on motorcycle engines (when used in conjunction with a resis- tor spark plug cap), in part due to their ability to withstand vibration. They are also used in some race applications, such as with magneto ignitions. Resistor core has been the most commonly used suppression-type wire. Its job is to slow the discharge rate and dampen the oscillations that occur on the secondary side of the ignition… reducing the tendency of the wire to act like a radiating antenna. The core is somewhat fragile and will erode. Spiral core wire has become increasingly popular in the last several years. Its function is also to reduce radio frequency interference (RFI), but by means of inductive reactance. As current fl ows through the wire, the spiral windings appear inductive, which by now you know means it opposes a change in current, again slowing the discharge rate and subse- quent oscillations, but does not con- vert as much energy to heat as does resistor core wire. Remember, whatever those entic- ing ads in the funny papers might say about "bigger, fatter, better…" chances are you're good to go with the type of wire your Harley's igni- tion system came with unless you've changed that system substantially! Meaning, wires should match the sys- tem requirements, and well-made and durable are the desired outcomes of any "upgrade." Digitalis No, not the herbs… rather, 21st century Harley-Davidson ignitions which are all true digital systems with crank "position" sensors (sometimes cam sensors) and all the trouble-free trappings. This makes them the best way to light the fi res in your Twinkie, ever devised by The Motor Co. Not a thing really needs to be changed or enhanced, beyond the possible excep- tion of iridium spark plugs. Yay! I only lament that along with the lack of need comes lack of options. For as long as most of us can remember… and even beyond living memory… imperfect ignitions could be improved. From the days of the magneto, on through many iterations of "cone" motor Sportsters (till '03) and Big Twins (Evo), to the end of that era. No more! Well, I'll ask you, where's the fun in that? We've gone from "have to do it" to "can't do it." A chore and a choice… removed at one stroke? From mastery to mastered. From participant in an uneasy alliance with physics and mechanics to digitized, abject Orwellian servitude in the name of … what… progress… preci- sion… performance? We're sold those notions, but didn't the EPA actually twist the arms of manufacturers to fi ght the dreaded "smog?" Gap, dwell, the skills to "fi x it and limp home," a faded memory to rival what it was to hand crank your car to life. The lore will be lost in time. Make no mistake, I wouldn't want to go back to the way things were, and I'm not saying we should… but I could. Could you? So, till next time, I'll just leave you with this: 90 percent of electri- cal problems are fuel related and 90 percent of fuel problems are electri- cal. The other 10 percent are both! Welcome to my world! As long as the condenser is of proper capacity, the points (contacts) are kept clean and adjusted and the rubbing blocks rub on a clean oiled point cam, there are few problems with what you see in this picture. The real problem is usually a lazy owner. Yes, this type ignition requires a little TLC now and then, but the simplicity and ease with which it can be persuaded to function is not to be underestimated. The advantage of electronic ignitions is, they need none of this… but they either work or they don't! Choose the Inbox Instead of the Mailbox Digital Edition Available on all Platforms. J $14.99 per year (12 issues) J Available one week prior to the print version J Page-for-page replica of the print version J Hot links to advertisers' websites J Save a tree: Every digital page is one that doesn't go through the paper mill iPad & Mobile www.thunderpress.net/subscribe Digital not for you? Get Print at $29 for 1 year (12 issues) www.thunderpress.net/subscribe