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few bucks more,but worth every cent

 

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Check this thread for some useful info.



I run the plugs the factory put in there in all my vehicles (well, except the diesel) FWIW.
 

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The owners manual states:



D8EA for overall riding



D7EA for extended high speed riding (colder plug)



D9EA for predominantly cold climate riding (below 5*C / 41*F) (hotter plug)



You don't need the resistor plug even if you don't have them in your plug caps, so ignore the R versions.

The numbers on the end apply to Canadian models and I doubt they really mean anything.



Gap is between 0.024 - 0.028



Tighten 1/2 turn past hand tight.
 

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You don't need the resistor plug even if you don't have them in your plug caps, so ignore the R versions.

The numbers on the end apply to Canadian models and I doubt they really mean anything.


This is incorrect.CDI ignition bikes require a resistor in the Spark Plug Circuit as do the,"Ignitech" replacement units,



http://www.ignitech.cz/faq/faq_en.htm
 

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Is what I hear about iridium plugs not "reading" the same as normal plugs for colour and richness etc true?



If it is, maybe stick to plain D8EAs until you know that your mixture etc. is all sorted before installing iridiums?
 

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This is incorrect.CDI ignition bikes require a resistor in the Spark Plug Circuit as do the,"Ignitech" replacement units,



http://www.ignitech.cz/faq/faq_en.htm


If you're using an Ignitech perhaps, but I don't think it affects the stock CDI. It does make sense though, might increase the longevity of the CDI or Ignitech unit by slowing/limiting the discharge time and instantaneous current.
 

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Is what I hear about iridium plugs not "reading" the same as normal plugs for colour and richness etc true?



If it is, maybe stick to plain D8EAs until you know that your mixture etc. is all sorted before installing iridiums?


I had Iridium plugs for over 5 years and they read just like any other Spark plug.I will be returning to them when I've used up my box of DR8 ES-L are used up
 

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get the iridium plugs.you only have to compare the 2 plugs to see that they are far superior.
 

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I had Iridium plugs for over 5 years and they read just like any other Spark plug.I will be returning to them when I've used up my box of DR8 ES-L are used up


Yea, I've used them in cars and they read the same, after all the only difference is that the center electrode is an iridium pinpoint and often surface level mounted. I wouldn't use them in a waste spark engine as half the plugs fire as "tip positive" and the others as "tip negative. This introduces the problem that the ground electrode itself isn't iridium so you lose the wear-out advantages, it's also the reason the AC-Delco plugs they used in waste spark engines for ages had a tiny strip of platinum on the ground electrode as well a being in the tip. NGK makes all those plugs for AC-Delco yet I've never found a cross for a double plat that would replace a D8EA or I'd use them. There have been rumors but never officially proven by a reputable laboratory study that platinum plugs actually serve a double advantage in an engine. Not only do th platinums wear longer (100K is claimed for the double plats but I can start measuring a gap change around 30K and usually replace them at 50K at which the original 0.060 gap has opened up to almost 0.080) but the unproven but believable other advantage is that the minute amount of platinum that's introduced as airborne each time the plug fires acts as a catalyst allowing the air/fuel mixture to burn more efficiently.



R121XLS is the replacement for a stock D8EA



Looks like I need to get in touch with an AC-Delco engineer I occasionally quiz on matters like this.
 

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Ignitech seems to require them, as far as still having the stock CDI it might increase the longevity of the box.
 

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I removed my resisters would it benifit i switch to the DR8ES-L And if so why just asking as i did not know this and still running the D8EA whats is the difference? hope that isnt a silly question.


Yes they would be better.The resistor helps smooth the interference that can be picked up by the CDI unit via the cables/current.That's why Honda used them.
 

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Thanks Shep, that's good to know as I'll be fitting iridiums at some point in the future.


Remember I run none resistor plug caps,



http://www.wemoto.com/bikes/Honda/CX_500_A/79-80/



I even ran them with resistor plug caps but didn't see the point in doubling up the resistance.As I have old CDI units I would never run the CDI boxes without at least one resistor in the circuit.They are pretty much,"Fire-and-Forget".I actually started to miss checking my plugs<grin> but still did anyway.I never once had to set the gap and you aren't supposed to anyway with them
 

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The owners manual states:



D8EA for overall riding



D7EA for extended high speed riding (colder plug)



D9EA for predominantly cold climate riding (below 5*C / 41*F) (hotter plug)



You don't need the resistor plug even if you don't have them in your plug caps, so ignore the R versions.

The numbers on the end apply to Canadian models and I doubt they really mean anything.



Gap is between 0.024 - 0.028



Tighten 1/2 turn past hand tight.
This is incorrect in many ways!



dr7ea is hotter than an 8 and 9 would be cooler the lower the number the hotter the plug! stick with an 8
 

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Yes they would be better.The resistor helps smooth the interference that can be picked up by the CDI unit via the cables/current.That's why Honda used them.
They were actually mandatory back in the days that AM Radio was pretty much prevalent, an ignition system without a resistor near the plug would interfere. Nowadays they're mandatory because that same interference can affect the computerized engine, transmission and body management computers.



Due to the sheer simplicity of our CDI design there's nothing in there to interfere with, their absence would just slightly reduce the strain on the HV output caps.
 

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It had nothing to do with being,"Mandatory".



http://www.benefiscal.co.uk/forum/index.php?topic=9302.0



The problem isn't one of excessive current draw... As stated above, the air-gap introduces a significant DC resistance into the HT side of the circuit...



The problem is one of "Back EMF", or reflected potential...



We're not actually talking about a DC circuit here, it's a circuit powered by DC, but only actually operating when that DC level significantly varies, so it's actually AC, which is why the HT coil works at all... (AC theory, transformers...)



Basically, the HT coil's secondary winding generates a very high pulse (30kV or higher). When that pulse jumps the plug gap, the Electromagnetic Force (EMF) generated in that winding collapses (almost) instantaneously. This sudden drop in voltage is "reflected" back into the coil secondary and, through transformer action, into the coil's primary winding, and from there, back to the TCI...



This "Back EMF" pulse can be in the order of a few hundred volts and it's for this reason that the output transistors in the TCI have a Peak Inverse Voltage (PIV) spec of 400V or more...



Adding resistors into the HT circuit significantly "damps" the reflected pulse, reducing the peak voltage. This has an additional beneficial effect in that it reduces radio wave interference too.



My 2p worth..? I know my TCI is nearly 30 years old... I use solid copper cored HT leads, NGK resistor plugs (Got some NOS BR8EV's fitted at the mo), NGK resistor plug caps and VF1000F coils... TCI has been on 2 different bikes (at least) and still runs AOK... seems like a recipe for success to me...
 

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I thought I'd add a reply to this thread as opposed to starting up a whole new topic.



I am learning (slowly) to be comfortable with tinkering with my bike, and so I checked the plugs today.



The Haynes says to use D8EA plugs for my '80 CX 500 Deluxe (I bought a pair to have on hand). However, the plugs currently in the bike are DR8ES-L.



So, out comes the screwdriver and I check the caps (has the PO done the brass rod modification?). This bike is really clean, incredibly stock, and so are the resistors inside the caps. So as far as I understand it, I have A PAIR of resistors attached to each plug (one in the caps and one resident on the resistor itself).



Should this pose a problem in the bike, or is it with resistors: "the more the merrier", or does it simply not matter? I can easily swap out the plugs if this is a problem.
 
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