I've got two resistors - one in the plug cap and one in the spark plug. Almost.
One of my NGK plug caps went bad, the internal spring that clamps the plug terminal wore out. So, without thinking about it, I bought some new NGK caps at a local shop but when I got home I noticed that they have built in resistors.
I like to run the iridium plugs but it appears that both the Denso and NGK lines of iridium center electrode plugs have built in internal resistors. As far as I can find, they don't list non-resistor plugs.
I wouldn't think that two resistors, one after another, is a good idea. Or, am I wrong?
I found that NGK makes a non-resistor plug cap - LZFH, #207-010, L = 90*, Z = plug body for 14mm thread, F = terminal stud type, and H = complact cap.
I have Tri-Spark's ignition and looking at their site, and at their Blog also, I found that they do recommend a resistor, that they do not recommend carbon core wires, but I do not see a straight out recommendation of copper wire or spiral wound or whatever wires.
My existing wires are fine - silver plated copper wire that the new NGK caps screw into nicely.
Has anyone else gone throught this?
What wires are best?
ITSec, RER and guzzisteve, that was my thinking from what I was reading on the "net". Makes sense to use only one.
So....Armed with this info, I grabbed my trusty multimeter and set off to see what my EV has. With all the help I was able to figure out what I was looking for!
I first figured out how to set the meter for the correct ohm range. I have a NGK resistor cap in my parts stash and played with the meter ohm range setting until it read 5.2K or the like.
So I first measured the resistance by pulling the plug wire off the plug and putting one test lead into the plug cap and one to a frame ground and found 8.2K ohm about. The coils on this bike, I think, have 3K ohm resistance. So added up, 3K for the coil and 5K for the cap is 8K ohm, the STOCK plug cap has a resistor built in (verified by pulling the stock rubber style cap off the wire, measuring the resistance and reading on the cap 5000. Go figure it was molded into the cap
So just like Wayne stated, the EV has a 5K ohm resistor cap and as per the manual for the required plug NGK BP"R"6ES resistor spark plug. Interesting??
It appears that for some reason Guzzi decided to go with both resistor caps and plugs on AT LEAST this model (probably more??). I would have thought only one as mentioned by the replies. Maybe the ECU needs more RFI reduction??
This all got started by the threads on bad plug caps leaving you stranded and thinking that I should replace the plug caps. I just wanted to make sure I used the correct plug cap.
Thank you all for taking the time to help me learn something I didn't understand!!
Heck, I may try the NGK caps on my Eldo and see if it makes a difference.
Tom
Ok I am going to give my take on what resistor plugs and wires do. The energy stored in the coil will build up until it can overcome the resistance of the plug the wire and the airgap in the cylinder then it will fire. If additional resistance is introduced into the system the firing will be delayed until the threshold is met ie the voltage will be higher than it would if a normal plug or non resistor wire is used. This obviously only works to a point when the voltage in the secondary circuit is insufficient to fire the plug and finds some other path to discharge. The resistance of the plug and or wire is of a lower order of magnitude than the airgap in the cylinder I believe that plug wires are on the order of 10 -15K ohms or so and the plug maybe 5K , my memory is not perfect on this, I believe that the airgap in the cylinder is several Megohms or more though that goes down in the presence of ionized products of combustion. The benefit of resistor plugs and wires is that they reduce radio frequency interference which screws up electronic devices, they also will fire in somewhat adverse conditions like carbon deposits on the plug electrodes as long as they are able to overcome the threshold voltage needed . Pretty much the polar opposite of what Doc said but I am listening to any logical arguments and am open to correction by wiser minds. Learn me. Cheers Dan
BigBlockChev said:
Ok I am going to give my take on what resistor plugs and wires do. The energy stored in the coil will build up until it can overcome the resistance of the plug the wire and the airgap in the cylinder then it will fire. If additional resistance is introduced into the system the firing will be delayed until the threshold is met ie the voltage will be higher than it would if a normal plug or non resistor wire is used. This obviously only works to a point when the voltage in the secondary circuit is insufficient to fire the plug and finds some other path to discharge. The resistance of the plug and or wire is of a lower order of magnitude than the airgap in the cylinder I believe that plug wires are on the order of 10 -15K ohms or so and the plug maybe 5K , my memory is not perfect on this, I believe that the airgap in the cylinder is several Megohms or more though that goes down in the presence of ionized products of combustion. The benefit of resistor plugs and wires is that they reduce radio frequency interference which screws up electronic devices, they also will fire in somewhat adverse conditions like carbon deposits on the plug electrodes as long as they are able to overcome the threshold voltage needed . Pretty much the polar opposite of what Doc said but I am listening to any logical arguments and am open to correction by wiser minds. Learn me. Cheers Dan
Click to expand...
Pretty much what I learned when a SUN salesman said while demonstrating the advantage of using the scope to troubleshoot ignition problems back in the 60s. He claimed that it would pay for its self in no time. I saw it as a tool to identify problems in the high voltage circuit.
Bob
Leon N. said:
My take on this. Resistor or no resistor, no spark, thus no current flow until the voltage over comes the series resistance of the circuit. When the current initially flows, that is the plug fires, the circuit rings at a hi frequency, thus the RFI in those older cars with radios. So, by adding resistance, the ringing is reduced markedly as the voltage will now decay quicker due to the added resistance.
Can you use a resistor spark plug with a resistor cap?
If the spark plugs are resistor type then do not use resistor caps. The 'back pressure' of current some electronic ignitions need is rather specific and over resisting will feck up the works. Ohm's resistance need's to be considered. I use copper wire, resistor caps and non-resistor plugs.Why is there a resistor in a spark plug cap?
Resistor plugs were developed in the 1960s to suppress some of the spark energy, thus lowering RFI to an acceptable level. Most resistor spark plugs use a monolithic resistor, generally made of graphite and glass materials, to filter the electrical voltage as it passes through the center electrode.Do spark plug caps need resistors?
Both work well with or without resistors. The coils will not be damaged without resistors on the secondary side to the spark plug. The spark plug tip may erode a bit faster. Mainly, resistors are used to reduce RFI.Do resistor spark plugs make a difference?
A resistor plug helps suppress ignition noise that affects other components, such as your sound system.