No don't worry this isn't one of those, what is the better plug brand to use. I'm one of those guys that change plugs each time I do a service, mostly when I do the 5K service. I think it's just cheap insurance to change them out even though HD says you can go long and just inspect. The 10K I usually take my bikes in. So here is my question each time I change out my plugs I use a standard OEM plug. Does it make a difference to use an iridium or platinum plug in your bike. I know they burn hotter and I wanted to know if that's good or bad or it just doesn't matter that much. The service manual of course recommends OEM and says nothing on performance type plugs. I have a 98 Fatboy with an S&S 88 in it that I put in last year after my stock EVO went out. I also have a 17 FLHTK that I haven't changed the plugs myself yet. I'm told the top ones in the M8 are a pain in the @$$ to change. So let me know what you think on the different cores in plugs and HD's.

 

What I've learned over the years about plugs is the length of the porcelain nose in the tip of the plug determines the heat range. the metal that is used on the center and side electrode, Iridium or Platinum reduces the wear on the metal electrodes. the smaller diameter of electrodes reduces the resistance the electricity has to overcome to generate a crisp spark. HD will rec. an OEM plug to make their share of the money also I believe their plug has some kind of ION sensing magic that detects pinging and makes timing adjustments before the operator hears it.

 

In my somewhat uneducated opinion, throwing out Iridium plugs that soon is likely wasting money. But maybe they don't cost too much....
I don't really know a lot, but I don't think Iridium or Platinum burn "hotter". I do know that the iridium plugs in my car are rated for 100K miles, so that may be the advantage of iridium over regular plugs.

If you're going to replace them after a short period of use, I'd stay with regular plugs.

I use HD branded regular plugs in my Limited, and replace them as called for in the manual- Every couple years, IIRC. And the ones I've replaced looked perfectly good, I bet they'd go another season easily.

 

champion

 

Iridium lasts longer. No other benefit.

 

Unless you have head work done.....there is no reason to use any other plug than the OEM.

 

I don't know.....just run which either one that is most expensive......OR whichever one NASCAR uses.

 

Run it till it gets a misfire code. Bet you never will replace them. They still look like new at 10 K in my old girl. I replaced them at 20 and the same. I doubt I will live long enough to do it again now at 50K

Now if I pulled them, I sure would not put old ones back. Not sure why you would pull them. They will tell you it's missing.

And use OEM Harley. Especial on older bikes for sure with ion sensing. The NGK plug you see is twice the resistance as the Harley plug. Back when I put them in, did not know any better. Although if you drive easy, it will probably not hurt. And I got good fuel mileage, so I guess they did not affect timing.

Those first Harley plugs got that way in a freak late ice storm I got in way South of VA and they sprayed salt brine all over the roads.

 

 

I will be straight with you as I have a strong opinion on this topic. Keep using the OEM plus and changing them every 5K. Then mail them to me so I can run the another 15K. Thank you in advance.