Spark plugs: resistor or non-resistor type?

[Reprobate]

I have slight problems with surging. I changed to a K+N air filter and intend to change spark plugs. On a German site [http://home.arcor.de/m.panitzki/html/bmw-gs/index_bmw-gs.htm], the writer recommended:

NGK
Die NGK-Kerze hat im Gegensatz zur Bosch- und zurChampion-Kerze nicht nur eine Massenelektrode sondern drei, eine sog. Mehrmasseelektrode. Welchen Vorteil hat dies? Im Vergleich zu einer Elektrode richten mehrere Masselektroden das elektrische Feld örtlich präziser aus, welches sich bei Anlegen der Zündspannung aufbaut. Der erzeugte Lichtbogen schlägt dann entsprechend präziser auf der gegenüberliegenden Seite ein und es kommt zu einer besseren Zündung des Kraftstoff-Luft-Gemischs.
Ich habe in meiner R1100GS in der Saison 2001 und 2002 die NGK BCP7ET mit Mehrmasseelektrode gefahren. Insbesondere in Verbindung mit dem K&N-Luftfilter wird ein wesentlich runderer Lauf bei niedrigen Drehzahlen sowie eine bessere Gasannahme erzielt. Dies macht sich besonders bei kaltem Motor positiv bemerkbar. Das KFR ist zwar auch mit NGK-Kerze und K&N-Luftfilter nicht vollständig beseitigt aber das Problem ist inzwischen marginal.

But when I consulted a list that compared NGK to Bosch, it said I needed the BCPR7ET. So I checked further and the R in the model number refers to the Resistor:

R = Resistor Type. A resistor type plug will not fire until the optimum current has been reached. Mainly helps stop radio interference. (Not Required)

So now I’m confused. The BCP is less expensive than the BCPR. What exactly does the Resistor do and would it harm my engine if I fitted the non-resistor type spark plug?

Perhaps someone with a more technical bent can give me a [simple] explanation whether I should buy a spark plug with or without resistor and why it matters.

Thanks.

 

[andy malton]

plugs

Try the brisk plugs plugs,they worked for me. Andy

 

[Panzer Patrol]

As you rightly said the resistor is there for radio noise suppresion. Unless you have a radio fitted, resistor plugs are not needed. Its summit to do with EU regulations that vehicles have to be fitted with them.

Should work OK with or without. Sometimes its not easy finding them without resistors. Manufacturers dont bother making non-resistors unless they are a really common plug.

 

[Rabbitson]

I had some resistor ones in my old GPZ600R and it didn't seem to make any difference.

Only bought them because the dealer didn't have any other ones, they were a bit more expensive but I needed them at the time.

Haven't tried them on the GS though so couldn't comment about that.

 

[Dave Hall]

garmin think that the non resistor types interfere with their equipment (they should be so lucky)

 

[(RIP) Dennis]

Try the brisk plugs plugs,they worked for me. Andy

And for me

 

[Greg Masters]

Go back to your A-level physics!

You will not get the best possible spark unless there is some resistance in the HT circuit. It could be in the lead or the plug, it doesn't matter, but you should have some!

Greg

 

[Roge]

Go back to your A-level physics!

You will not get the best possible spark unless there is some resistance in the HT circuit. It could be in the lead or the plug, it doesn't matter, but you should have some!

Greg

The air gap in the spark plug is a very high resistance, higher than any R that is incerted for suppression purposes

 

[Greg Masters]

The spark plug gap is, of course, a resistance point but the object of the system is to build up a sufficient charge across the spark gap. Once the voltage of that charge is high enough to ionize the gas between the electrodes (and that varies according to pressure and mixture), the ionized gas creates a conductive path for the current to flow and the spark starts.

The duration of the spark is determined by many variables but, primarily, the rate of collapse of the magnetic field within the coil when the primary current flow is stopped. Once the spark has started, its duration is determined by the coil inductance and the resistance of the HT circuit.

HT lead resistance also suppresses Radio Frequency Interference and can safeguard against coil and primary voltage amplifier damage due to flyback and coil harmonics.

Greg