Author Topic: I've never really understood resistor plugs / caps the effect it has.  (Read 234 times)

Offline McCabe-Thiele (Ted)

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I might be completely wrong here but my memory of resistor plugs is that they seemed to appear at around the same time as carbon plug leads in the battle to stop inteference on your radio & to a neighbours TV. Certainly back in the 1960's you sometimes heard and even saw a crackle on your TV screen when certain vehicles were close to your house.

If you fit a none resistor plug to an engine with no resistor in the plug cap how does this affect the way it starts or runs - is it related to having carbon leads or copper leads?

Does the resistor aspect affect the timing?

I have the Dynatec coils & electronic ignition kit on my 400/4  that comes with carbon type leads and the plug connectors are just a metal connector with a rubber shroud so no resistor.

Should I use resistor plugs (NGK DR 8ES-L) in this situation what effect will it have to have none resistor plugs as I have fitted at present (NGK D8EA)?

I am somewhat ignorant as to what reistance does in the ignition circuit - I've read some articles here & elsewhere about the duration of the spark and how it affects the fuel burn but tbh it's way above my head.
Honda CB400 four super sport

Offline Sesman

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Hi, Ted.

Some interesting questions. I’m no ignition expert, but yes. ‘Suppressors’ came about in the 60/70s in an attempt to eliminate AF ignition wave transmission. The notion was to reduce the high voltage impulses

If the suppression was purely resistive (no capacitance or inductance) then timing of the spark would remain unaffected. The way I see it introducing a series resistance creates a voltage divider and this would lower the ignition voltage, potentially (pardon the pun) leading to misfire due to a low energy spark. Ie the compression and vapour blows out the candle.

Offline heli_madken

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Hi Ted, I pondered this question myself. The Dynatec leads have suppression built in so I wondered if I should be using 'R' rated plugs so I wrote to Larry Nelson in Dynatec technical support, this is what he said -

Quote
It really does not matter if you use a standard or resister type spark plugs. You could actually use the DW-800 plug wires suppression core plug wires with resister plugs and never notice any difference.
For this reason, we will leave this at your discretion, but you can't go wrong either way!

Currently using R rated plugs in my GL1000 with a Dynatec set up and runs great, opposite on my 550 and runs great so it does not seem to matter which way

Offline McCabe-Thiele (Ted)

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Hi Ted, I pondered this question myself. The Dynatec leads have suppression built in so I wondered if I should be using 'R' rated plugs so I wrote to Larry Nelson in Dynatec technical support, this is what he said -

Quote
It really does not matter if you use a standard or resister type spark plugs. You could actually use the DW-800 plug wires suppression core plug wires with resister plugs and never notice any difference.
For this reason, we will leave this at your discretion, but you can't go wrong either way!

Currently using R rated plugs in my GL1000 with a Dynatec set up and runs great, opposite on my 550 and runs great so it does not seem to matter which way
Thanks Heli thats very useful information. Cheers Ted
Honda CB400 four super sport

Offline Sesman

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That’s good news. It seems to verify that the even with suppression in place the resultant spark energy is just fine for a standard motor.

 

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