nklr resistor vs non-resistor plugs (at least it isn't an oil th

[RobertWichert]

"I run res plugs in 1-3-5-7 and non res plugs in 2-4-6-8 Best of both worlds." HA! Good one! Robert Wichert P.Eng. LEED AP BD&C +1 916 966 9060 FAX +1 916 966 9068 ===============================================

On 4/4/2012 8:08 AM, Jeffrey wrote: > > This issue about resistors verse no resistors in spark plugs is more > complicated than Ohms law. > > The 0.035" gap in the plug is essentially an infinite resistance > basically the 5K in the plug is trivial in comparison at this point. > As the voltage builds up in the secondary windings of the coil after > the points open or the ecu switches off no current is flowing in the > secondaries. At some level of voltage, it varies depending on the > conditions (in a lab at standard atmospheric conditions 2800 volts to > 20k or more volts in a running engine) the voltage will ionize the air > in the gap creating plasma and the resistance across the gap > essentially goes to zero and current flows (the voltage goes no higher > at this point) resulting in the plasma being heated to a point that it > can ignite the mixture and be visible to the eye. > > Reducing the resistance will allow more current to flow making for a > "bigger" spark but at the cost of the voltage droping below the point > that the ioization can be maintained faster. So the question is, > besides the RFI implications, do you want a "bigger" spark for a > shorter period of time or a "smaller" spark for a longer period of time. > > >From a performance stand point there will be experts out there that > can argue compellingly on both sides. I think anyone would be hard > pressed to be able to show any kind of objective evidence that one is > better than the other. > > > I run res plugs in 1-3-5-7 and non res plugs in 2-4-6-8 Best of both > worlds. And I used to race Nascar. > > > that isn't the question > > > > the question is whether my 2007 Vespa cdi and coil work better with > or without > > resistance > > > > > > > > That schematic of the S. plug is wrong the resistor is supposed to > be series not parallel. > > > >> > >> Resistor Plugs versus Normal Plugs > >> There has been a great debate over the use of resistor plugs in > Vespa scoots. Generally, they are not a good idea since the NGK spark > plug cap fitted in most p200s is already resistive, and the ignition > on Vespas is pretty underpowered when compared to modern motorcycles. > Let's have a look at the theory behind a resistor spark plug. > >> Impedance Matching > >> > >> > >> The reason to use a resistor spark plug is mainly to reduce radio > interference into the environment and to protect the High Voltage > electronics from the damaging side effects of reflections of a high > frequency, high-power situation. The most common place we observe the > effects of line reflections is in every day cable TV splitters. If we > have a television set connected to one side, and an unused split > connection on the other (open-circuit), under worst case > circumstances, the television set will display a garbled picture. The > reason for this is analagous to throwing rock in a perfectly still > pond. When the rock hits the water, waves ripple in a spherical > pattern; throw another rock in the pond and you will get overlapping > waves. In an electronics sense, you have ruined the information being > sent and risk sending a more powerful wave back to the transmitter and > other receivers in the chain. This phenomenon is called an impedance > mismatch. If a resistance, 220 ohms in the case of televisions, is > inserted in parallel to all the other circuits, it will channel all > the unused energy at a split into useful work instead of wasting power > in the environment. Thus, the resistor will prevent the picture from > degrading. > >> Resistor Plugs > >> > >> > >> In our previous example, we were shown the effect of reflections on > a television, now we look at the spark plug. Using a normal spark plug > without a parallel resistance, we render all personal communications > equipment useless. The reflections from the spark plug produce > unwanted harmonics that interfere with any radio equipment you may > have. Okay so what do we do? The magic number is 5000 ohms (or 5k) as > 5k ohms is roughly matched to the characteristic impedance of the > ignition transformer. If we put a 5kohms resistor inside the spark > plug or the plug cap, the resistance will balance the transmission > circuit and provide maximum energy to the spark plug's anode. Since > there will be much less unused energy, the circuit will release much > less electromagnetic and radio radiation. The end result is that we > get a more efficient spark and less radio interference. The problem > with the integration of a resistor is that it is designed for newer > ignition transformers. The P200' s ignition system's characteristic > impedance may not be as high as 5kohms so the resistor may not balance > the circuit like it should, which makes the system less efficient. > Some find that their bike will just die once enough carbon collects on > the center electrode. NGK even warns people on their site about the > complications associated with older ignition systems, but so far I > haven't experienced any igniton problems due to failure of a resistive > plug. > >> Selecting a Spark Plug > >> Whew, an easy topic. Buy a B8ES. Done. No? Wait. So you're in a > pinch and you need a spark plug. There's a B8HS and a B8ES R and a > B8EGV and etc. Maybe one of these will do? Careful now, lets not do > anything rash. What's the difference here? Okay, I see a problem > developing here and it comes up again and again. Here's a table for > what to buy. This table is for stock bikes. > >> > >> B9HS, B8HS, B7HS, B6HS - These are short ended spark plugs and will > not work with a P200, so ignore them. > >> B9EGV, B8EGV, B7EGV, B9EGV - These plugs have a tiny center > conductor in them and may not always be made of copper. I have had no > experience with these plugs, but from NGK's site, they appear to be > for high end motorcyles, not Vespas. > >> B9ES - This plug may cause erratic running at city speeds, and will > foul easily because it runs so cold. if you are running 'lean' because > of your carb, this plug may be a temporary fix. > >> B8ES - Utopia. this plug is perfect for slow city riding and runs > fairly cold for highway rides. > >> B7ES - A bit hotter than the B8ES. This plug is reccomended for > quick city rides because it will not foul easily. If you're going on > the highway go a little colder. > >> B6ES - This plug runs 'hot' this plug should only be used for > special circumstances where the engine may not be getting to full > temperature or the carhb is running rich (too much oil/gas mix). > >> 'R' - R means resistor plug, there is a 5K resitor in parallel with > the spark plug electrically to provide less EMI (Electromagnetic > Interference) and RFI (Radio Frequency Interference). See my lengthy > discussion of the pro's and cons of this plug above. These plugs > aren't a bad idea because they generally make the system work better. > > [Non-text portions of this message have been removed]