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Stock 6R12 Plugs

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wilks3

Junior Member
At my 5K checkup that I did myself I changed to HD 6R12G spark plugs, thinking I was upgrading. It took about 400 miles to see my mistake. Little by little bike was having to crank over more to start. Past Sat turn on switch, let fuel pump stop and lights go out in the speedo. Crank over, don't start.
Crank over again, no start. Turn key switch off, wait, turn on, let fuel pump stop, idiot lights go out, crank over at least 3 revolutions, finally starts. All sounds good, go for ride, everythings great. Bike has always started at touch of button, always.
Got to thinking about the Ion thing and you should only run stock 6R12 plugs.
I put the 5K mile 6R12 plugs back in next day, bike started up like it always did. Have ridden 200+ miles since Sat, bike starts at the touch of button like before.
Stock plugs were 9ish K ohms. The "gold" ones were 34ish K olms.
Proved it to me, stock 6R12 are the way to go, at least for my FatBoy.
wilks3
:USA
 
Since i started on Harley bikes i have always used the stock plugs and as yet have had no reason to try anything else as they are reasonably priced readily available and work well with my engines

Brian
 
I switched to Autolite 4164 copper core pulgs at my first plug change and have used them only. With over 80k miles on my 03 FXST they work for me.
Don't want to start a debait just saying what works for me.
 
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Factory O.E. plugs for me 20,000 miles on bike and 3rd set of plugs and bike runs great. No problems.. The dealer always wants to sell me Screaming Eagle plugs though.
 
I too took out the FREE screaming Eagle plugs and put the stockers back in wow:s
 
I checked a Screamin Eagle "split-fire type" plug, 5.91K olms. A Screamin Eagle double platinum plug, 6.31K olms. These plugs ran over 10,000 miles each in a 2007 FatBoy with no problems.
It makes no sense of all the different olm values for plugs that HD sells and recommends that in some bikes they work and some they don't.
Confused for sure now. Any thoughts?
wilks3
:USA
 
wilks3 said:
I checked a Screamin Eagle "split-fire type" plug, 5.91K olms. A Screamin Eagle double platinum plug, 6.31K olms. These plugs ran over 10,000 miles each in a 2007 FatBoy with no problems.
It makes no sense of all the different olm values for plugs that HD sells and recommends that in some bikes they work and some they don't.
Confused for sure now. Any thoughts?
wilks3
:USA
Click to expand...

IMO just because the bike ran with XXX plugs in it, there's no way for someone to tell if the ION sensing is working. This is the critical part that can do damage to an engine. Most any plug will work if it can fit the threads if the head to be installed but only the correct one will work properly.
Even the wrong heat range will screw into the head but damage will result from it.
 
Thats all true, but, my Ion sensing gizzmo is hooked up. So why would plugs that HD sells and recommends work in some bikes and not others?
It just doesn't make sense and there's got to be a reason.
Still confused....
wilks3
:USA
 
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