Soooo, I decided to throw in some Iridium plugs since they needed changed out anyway. She's a 2009 Heritage Softail Classic w/ 18,000+ miles. Put in the new plugs and runs like crap gapped at .40. I know the tolerance is .038 - .043...would changing the gap make a difference? I'm about to throw in my old plugs to have it run right. It idles like crap and pops like it's lean with the new plugs.

 

I just Run the Stock Plugs , I tried-um all , Stock plugs run cooler too
I gap-um at 40 also , Put your old plugs back in and see if that fix it ,, Good Luck

 

your not supposed to gap iridium or platinum plugs.... you prob broke them,, just get the platinum harley plugs,, they are like 15 bucks for the set,, throw them win and call it a day...

 

Also check the porcelain on the plug if they've been dropped before it could be cracked and would make it not fire right.

 

I have heard that they (the Iridium) can throw a code due to a different amount of current draw to fire the plug. It has to due with the adaptive knock control. I use the cheap ($1.77) plugs from Shcucks, and they work fine.

 

Read this and U'll know why I still use the same plugs that came from the factory..

Make sure U read what it says at the bottom of the page at least.

http://www.harleyhelp.com/sparkplg.html

 

Never heard that one before. I gaped mine when I ran them and they were just fine, the bike idled even better and seemed to start quicker. I do run stockers from J&P, OEM HD and much cheaper than the stealer.

 

Thanks for the info guys, I'll just regap my originals and throw them back in and grab a regular set. Just sucks to waste $20, I'll see if my indy shop will take them back or not. No biggy.

 

As 2008crossbones said, I agree....
I was running pipes a while back without ac or tune, had a ton of pop at decel.
Swapped to the HD Screamin Eagle plat lugs (the ones for stock compression), and a set of SE wires.
Popin went away!
Great set up!
and cheap imo...
19.99 for wire set and 14.99 for a set of plugs.

 

Mine won't run with them either out of the box.I run the old SE plugs that I'm about out of.XP12 Y if any one has any new ones for sale.