FI HD motors use the 6 Ohm resistance plug as part of the ECM anti-knock management. Does not "listen" to the motor. It senses an increase in the combustion chamber resistance to know when and how much to retard the spark.

There is no microphone any where.

One can use any plug they want as long as it is a 6 Ohm resister plug. Unless one does not care about pinging.

 

Maybe on a harley forum you'll get flamed.

But...I'm in the auto business (mechanic, and also own a car sales business) and I can't really ever remember anyone saying anything good things about champion plugs. They are prety much the bottom of the barrel choice. Most of our parts suppliers don't even offer them when we call for options if we need plugs for a customers car. Lol

 

Entertaining and fact based thread!

 

On this same subject, does anyone have a recommendation for what's the best performance plug on the market for a Harley 1450?

 

Just as an experiment on my 2005 Sportster XL883, I replaced my iridium NGK DCPR7EIX with the next step COLD plug, only copper instead of iridium, NGK DCPR8E and my bike hated them (I apologize if I have already posted this in another place.) because it started up perfectly, warmed up perfectly and ran perfectly at 50 mph for almost 2 miles and then got the hickups. I think the wind blowing over the engine cooled it down more than it liked because when I slowed down to return to the house at 30 mph, it ran normally again. Definitely did not need the cold range plug.
I checked my original iridium plugs for condition and .040" gap, put anti-seize on the threads and re-installed them. Back to normal. Next scheduled service at 10K miles, I think I will go with the same heat range in copper (NGK DCPR7E) to see if they run as well for the same distance. The iridium plugs cost 4 times the copper ones, so why not.
The only problem I've had with runnability is when I shut down the engine immediately after a long hot run on the interstate, it will OCCASIONALLY run-on. If I give it time to cool down before shutting down, it does not run-on. That's why I experimented with the cold range plug.

 

I buy the Harley spark plugs instead of the Champions (and I have to buy 4 of them). The Champion plugs don't gap to .040" very well.

And the Harley-Davidson plugs have great old nostalgic packaging.

And the parts people are friendly to talk to as are the salespeople waiting around hoping to sell me a newer model.

And I am treated better at my Harley-Davidson dealership than at my local Apple computer store.

 

UPDATE:
I tried the NGK DCPR7E copper plugs today to compare to the DCPR7EIX iridium plugs that I've been running for the last 3K miles. Since the weather is still the same I figured it would be a good time to compare the same heat range plugs in different metals.
The bike started just as quickly which means instantly. However, it took longer to warm up and the bike seemed to be "cold-natured" for a longer period of time/miles. Once completely warm, I climbed a hill that I ride almost daily in top gear and the bike SEEMED a little anemic -- purely subjective observation but it just didn't feel the same. I've never had any problems with the iridium plugs other than the occasional "run-on" after a long hot run and I am not sure the plugs had anything to do with that, anyway. So tonight, I'm putting my iridium plugs back in. Maybe I'll just run them longer and check them every 10K miles.

 

Yup! just went to the auto parts store and got a couple of Champion copper core plugs for $1.89 each and didn't think twice.