| Author | Message | ||
     Fast1075 |
I pretty much ran thru the threads and never found anything about basic spark plug tech...in the event I am in error, I am sorry. So in the interest of those newer board members who may be very new at engines in general. The basic job of a plug is to ignite the fuel/air mixture. An electrical discharge created by the ignition system jumps the gap between the center electrode and the ground electrode. The resulting hot plasma ignites the fuel/air mixture...and it has to do this under extreme heat and pressure. Heat Range: typically referred to as cold, hot or somewhere in between. Heat range refers to the temperature the PLUG runs at when used in an appropriate application. It is the application that determines the required heat range. The physical property that most determines the heat range is the lenght of the path the heat must take to get away from the center electrode..cold plugs have very short center insulators making the past short...hot plugs have long center electrodes, making the path form the tip to the body of the plug where the heat is dissipated by conduction into the head. Too cold a plug, and it will foul due to the surface temperatures being to low to burn off combustion byproducts and unburned fuel or oil. This is usually associated with low load/low rpm engines such as stop and go commuting or engines with poor oil control or excessively rich mixtures such as race engines with carbs that have no adjustable idle mixture circuits. Too hot a plug and you get into really dangerous ground. If a plug is too hot in range for the application, the surfaces of the plug get too hot because of the long heat pathway...as the surfaces get hot they begin to glow as they slowly oxidize away...now the engine doesn't need the electrical spark...since the glowing metal bits ignite the fuel/air mixture...you lose control of the spark timing...this creates preignition that causes a host of deadly engine conditions..the hammering will mechanically destroy parts..and the runaway combustion will burn up other parts. | ||
| Fast1075 |
Some myths and misunderstandings about plugs: "Changing plugs make an engine run better"...ONLY IF...There was something WRONG with the old plug, OR in the process of replacing the old plug you corrected some deficiency in the ignition system! "Plugs with a zillion electrodes kick single electrode plug's butts" Entirely untrue..the more electrodes you have in the way between the mixture and the spark, the more likely for poor ignition...this is called spark shrouding...the less the better...super quad electrodes are a marketing gimmick and hinder performance in many applications. "When plugs die" there is no timestamp on a plug...it dies when it is mechanically worn out...the surfaces of the electrodes oxidize away creating the characteristic wide gap and rounded surface appearance. Or they die from fouling or erosion due to poor heat range selection. Death by wear is largely determined by the materials used in construction...there are two basic TYPES of plug...Conventional...which use tungsten based alloys....Exotic Alloy...the exotic alloy plugs have much more erosion resistance which is the reason they work for so long. (assuming the heat range selection is correct)..current state of the art is Iridium alloy..no black magic, just good material that is very wear resistant...very expensive, but we only need ONE!  Platinum plugs were developed for one simple reason...manufacturers needed a plug that would live thru the end of the emission control warranty period..other wise if they used regular plugs, they would have to give away quite a few free tune-ups... | ||
| J2blue |
Thanks for the background info. I knew about half of it but not the "hot/cold" concept. Makes sense, though. Just thought I would throw out what this gal at Bumpus HD/Buell told me about the split fire plugs...they shed metal and wrecked her engine. Gimmick indeed! | ||
| Gearheaderiko |
That sounds like a case for the Mythbusters! or something that was said to avoid paying out on a warranty. I have a hard time believing it. Considering the amount of metal that collects on a magnetic drainplug and the relative size of a sparkplug (the part that actually faces the combustion chamber), for a spark plug to actually "shed" enough metal to cause engine failure would render the spark plug inoperative. I've used Splitfires for years and I can tell you that (especially) on an old worn out bike they can make a huge difference in starting. I've never had one fail or look like it was disintegrating . Not going to argue its the best either, some very nice plugs have come out (like the Iridium) since I first started using them 20+ years ago (on motorcycles). (Message edited by gearheaderiko on August 17, 2008) | ||
| Fast1075 |
In most cases a "standard" plug will be worn enough before 50k miles to misfire, affecting the smog output...in some states this is well before the mandatory mileage that the smog system is required to function under warranty...the car manufacturers turn this around and say "no tuneup needed for 100k miles. | ||
| J2blue |
No need for the mythbusters, I should have used a better word than "shed". One of the "tips" on the fork-tongued devil broke off as it was reported to me. Could have been a one in a million defect in the plug, or something else that collided with it. Or it may have failed in that application. Anyhoo, it is only one data point and not a conclusion. | ||
| Ezblast |
The Iridium Racing plug may outlive the life of the vehicle - so they say. Stills fires strong - dirty brown - no black - they are suposedly self cleaning - new looking in shape - probably check on them again in another 5000, but each time the plugs have looked fine. EZ | ||
| Gearheaderiko |
J2blue: That makes a little more sense. I'm still suspicious about the outcome, but I didnt mean to be harsh. | ||
| J2blue |
No problem.  | ||
| Fast1075 |
If it's dirty brown, it's way richer than it needs to be | ||
| Ezblast |
More power - haven't figured out the science behind it, except these motors are delivering more power on the rich side - my plug shows no black, and the bikes are both responding nicely to rider input - I have no complaints - I can launch the Daily Driver at 3000 rpms and she'll haul butt screaming, or I can launch from 2000 on the toy and quietly book away from everyone - my AF is fine and for the jetting I'm running that says a lot about both my parts combo's for this engine - Scott's plug looks the same, which says how well the Radical Air Box mod and Poor man's Force is working as well - very well indeed - he never thought his bike would accelerate like that without head work and a cam - lol Those plugs rock! EZ | ||
| Indybuell |
I just ordered myself one. | ||
| Reuel |
Richer, burns longer than leaner. Less efficient, but you get more pressure pushing the piston by the time the exhaust port opens. | ||
| Roysbuell |
I am changing my spark plug today or tomorrow. I live in South Texas where saying its hot is an understatement what spark plug should I use? | ||
| Ezblast |
Iridium racing - see my profile for stock number, and never have to change a plug again. EZ | ||
| Roysbuell |
Denso Iridium Racing Spark Plug. Part # IXU01-27 is this correct? I went to Autozone they had no idea what I was talking about. He askes "What type of car?" I said "A motorcycle" And then he looks at me like a deer caught in your headlights and said "I don't, I don't...WE don't have..." so I said "Thanks anyways" and left. So I come back and look it up online I find it at Advance Autoparts and its listed at $35.95 is this correct? Is there an NGK equivalent? One other question, does anyone working at any auto parts store know how to do anything the old fashion way..WITHOUT A COMPUTER? I remember walking in with a radiator hose the guy grabbing it looking at it from a few different angles and saying "Hold on, be right back." and a couple minutes later showing up with the right hose. | ||
| Evilbetty |
I've been having the same problem as of late. I walk in with a part number for a spark plug or a oil filter along with a print out of the part from their own website, and they ask "What car is this for"... It's for a motorcycle. We don't carry motorcycle parts. If you insist MAYBE they will go back and look at the alpha-numeric arranged part numbers on the shelf, but not always. I've found it better to Google the part number and see what car it comes up for. Then when they look at you as if you asked for a "ham-ikka-schnim-ikka-schnam-ikka-schnopp", you can tell him you need an oil filter for a 1993 Toyota Corolla and put his mind at ease. | ||
| Evilbetty |
Oh, and the plug numbers are in the text above these threads... the NGK Iridium plug is NGK #DPR9EIX-9 (stock #5545). The stock number is eventually what Advance Auto Parts was able to look the plug up with. Make sure before you buy it you make sure it has the nipple for the boot contact screwed on, and not just a bolt thread showing. | ||
| Roysbuell |
Thanks! ...and I won't forget to look for the nipple. | ||
| Roysbuell |
Still can't find a local auto parts that has the Denso plug in their computer. What is the next best plug? | ||
| Ezblast |
Order it at sparkplugs.com - autoparts stores only carry that which will turn a profit. Denso is not that kind of item - lol EZ | ||
| Reuel |
I always look for nipples. Did I type that out loud? | ||
| Hld01blast |
I have searched the service manual without success to answer this question - what gap for a standard plug? I bought mine at the H-D dealership Saturday, but cannot find what to gap it at. Thanks! | ||
| Hld01blast |
I have searched the service manual without success to answer this question - what gap for a standard plug? I bought mine at the H-D dealership Saturday, but cannot find what to gap it at. Thanks! | ||
| Ezblast |
0.038 to 0.044 - if I remember right EZ | ||
| Gearheaderiko |
See top of page! (I posted the answer twice and deleted it since it was ignored. I then posted it at the top of the page for future reference). I think after 24 days they'd have found the gap by now!!!  | ||
| Ichavis |
Is there anything wrong with using a DCPR8EIX? If i google buell blast and iridium i come up with that one and the NGK guide references that part. THanks, Ira | ||
| Ezblast |
Put a 9 in replacement for that 8 and you have the right heat range - 8 is a tad hot. EZ | ||
| Serpa |
I am having a hard time finding a listing for an Iridium plug. I found a DCPR8EIX is this the correct plug for a Blast? | ||
| Ezblast |
No - you would want DCPR9EIX. EZ |
