Topic: Spark plugs

[aminemed]

Hi

Just changed my four spark plugs for my CB 750 K2 and I just realized that the spark plugs are NGK D8R8EA instead of D8EA. Is it ok if I keep these spark plugs or should I throw them away and go ahead with D8EA right now ? thank you

[TwoTired]

The small added resistance will still work fine.  Maybe even better.

However, it is part of larger circuit which includes the plug caps wires and the coil itself.  Do we assume all these other components are stock devices?

Cheers,

[aminemed]

All other components are stock, didn't change anything

[TwoTired]

All other components are stock, didn't change anything

Then it is unlikely you will notice any difference in operation between resistor plugs and non resistor plugs.  Certainly no need for any alarm.

Cheers,

[aminemed]

Thanks

I had the impression that increasing resistance (sparks then plugs) would diminish spark power

[TwoTired]

Thanks

I had the impression that increasing resistance (sparks then plugs) would diminish spark power

A common myth that is simply untrue.  The coil/spark system does not behave as a simple DC circuit would.

Cheers,

[Dunk]

I believe NGK resistor plugs are 5k ohms built in. If your caps are 5k ohms you should be alright. If they measure much more than that you may start having issues particularly if you have stock coils.

I was having a slightly not perfect idle running NGK iridium resistor plugs with non solid core wire and Dyna 3 ohm coils. Measured resistance of wires and worst was 9300 ohms, that plus 5k in the plug is a lot. Replaced wires with copper core and it idles better. Also cleaned plugs while I was in there, though they weren't particularly bad, but that may have contributed to the improvement too.