HarleyTechTalk

Best plugs,
 for a 99 evolution Softail custom 80 cubic inch.

Maybe somebody has put up a survey in the past that might be available not sure if I've seen that?

Any case , trying to sort through all the different plug varieties copper, copper core, platinum, platinum plus, iridium,,
what's your experience and thoughts on all these variations?

I used the Autolite 4265 in my Evo, and still use the Autolite 4164 in my carbed Twin Cam. Cheap, available at all auto parts stores. I gap them at the low end of the recommended range, right around .035". It's been shown that the high end plugs are mostly a waste of money on such simple motors as these.

You cannot view this attachment.

I use Champion RN12YC in an 88' Heritage, and a 94' FLHTC gapped at .038, and Champion RA8HC in an 03' FLHTCUI with the same gap.
No issues with either.

I use the same as Fugawee   Autolites are my second choice.  Nothing wrong with the OEM plugs, but Champion plugs are cheaper and easier to find at your local parts store.  Champion makes the OEM plugs and has for 100 years.

I use the Autolites because when MSD Ignition Systems (Multi Spark Distributor) did testing on their system, they found the Autolites worked better than the others, including platinum, split fire, etc. I figured good enough for them, good enough for me.
Nothing wrong with the HD or Champion plugs either. Just wanted to point out that the expensive Platinum etc. plugs were not worth the money.
In my '12 Ultra with the knock sensor I run stock HD plugs.

We use the same Autolites as Hoss on both models.  Good life for low dollars.

Denso IRidium,used them in my carbureted Tc. Quick start and smooth idle,pre gapped.

My opinion is you won't be able to tell the difference in any of them when they are new.  The high end expensive ones will last much longer because the electrodes are harder metals and thus they will still be running good when they have many miles on them and a cheap plug would be long ago worn out.  If you change then every 10000 miles like the manual suggests run cheap ones.  If you want something that might last perhaps the life of your engine get some iridiums.  They might cost 3-4 times what a regular plug will and will probably last 3-4 times as long but they will not make your engine make more power or use less fuel.  I use them because it is one less thing I have to worry about.

NGK iridium