very little difference in any plug really... except heat range and size.... they all work really well... and they are all fairly cheap.... stay with the ones that came with your bike new... OEM harley..

 

I seriously doubt spark plug technology has changed significantly in 10 years... especially for an air-cooled V-Twin engine...

 

I find all spark plugs the same some just last longer.

 

[QUOTE=Todd Lewis;19360452]You may not have changed, but technology has in 10yrs,[/QUOT

I've done a lot of changing in the last 10 years, whether I wanted to or not, and I recognize that technology has changed as well. Just a suggestion that if you want to talk about modern technlogy in spark plugs, maybe you should have created a new thread, not resurrect a 10 year old one. It seems to have the "old tech" information in it.

 

I got sucked into the Spark Plug thing, got those $20 apiece Platinum, multi-posted, Gold Coated, Iron Man drag racing smart plugs. Guess what, nothing. I now run Champion spark plugs from Autozone $1.10 apiece and they run just fine. It is all hype. All you need is a spark to start the fire. And you know, once your engine hot, it don't take much to keep that fire going.

 

Just changed my HD plugs for some cheapo autolite .....No differentce at all. Probably won't last as long but I change them very 2 yr.

 

I've been a long time Champion user in Harley's since I had my Panhead. So a month or so ago I took my plugs out to see how they're doing. Both didn't look bad but the electrodes were worn down. So off I went to NAPA for a new set. In case you weren't aware NAPA stands for, no auto parts available. They didn't have any but could order some and have it tomorrow. I said screw it and went to advanced auto. They didn't have the champions either, but said they had NGK plugs that were a match. I never tried them before and took them. I know the plugs Harley's need are resister plugs, but the manual doesn't say what that resistance should be. Or what the high and low limits are. I read the old ones and the new ones with my multi meter. The older ones had almost twice the resistance as the new ones. I said lets give them a try. I gapped the new ones at .038 and put them in. The bike fired right up alot better, then with the old champions. Now to see how long they last. Price wise they were the same as the Champs, like $2.99 each. I didn't have any operational issues with the old champs, and the NGK plugs seem to be running fine also. I like trying different things on my bike to see if factory parts actually do anything different, so if someone asks my opinion I can't tell them my thoughts based on experience not hearsay.,,,

 

The Twin Cam engines use ion sensing... I've always used Champions or OEM plugs, but I have heard that some plugs don't work well with the ion sensing... It is something to consider when trying different "high speed" plugs...

In a nutshell... "Harley Davidson uses an Ion Sensing System to determine proper detonation. This system detects detonation or an engine misfire in either the front or rear cylinder, by monitoring the electrical energy at the spark plug after every timed spark. If an abnormal level of energy is detected across 2 or 3 spark firings the HD ECM responds by adjusting (retarding) the spark timing in that cylinder as needed to eliminate it."

 

I use the same spec in the standard plug, not iridium. Seems I don;t ride as hard as Harley thinks I should and the recommended Harley and Champion plugs get a little dry crust in 7 to 10 thousand miles and start to misfire. There is no warmer plug available from Harley so these one heat range hotter plugs stay clean. If Harley offered a hotter plug I would use it. Even if the $20 plugs actually worked better (improved mileage and performance) you couldn't save enough on gas to break even so they are a waste, as indicated by many previous entries.