Stock HD plugs or Champion plugs (who makes the HD plugs) work just as good as all the fancy plugs out there. Their purpose is to light off the mixture and after that, it's job is over. The fancy/expensive plugs don't do it any better than the stock ones do. Only difference is the fancy ones sometimes last a bit longer but I would rather put a new set in every season regardless.

Some of the platinum plugs will set a code in some of these bikes because of the ion sensing in the ignition system that senses secondary ignition resistance to retard timing when there is a ping detected.

 

Which autolite r u running ?On my 07 flhx i Just put in mp4164 {fine wire platinum} the only ones my shop had in stock , seems to start harder but only the first short ride.

 

I have just put in Autolight 4164. Seems to be OK. The FIX MY HOG DVD says HD plugs only. Not sure why?

FROM THE WEBSITE:

A special thread and shell coating ensures quick and easy removal from aluminum heads and resists corrosion. A gold palladium insert extends life and improves resistance to corrosion. The tapered tip provides better spark exposure to air/fuel mixture and allows the mixture to flow more easily through gap area for maximum combustibility. Fouling resistance is improved with smaller diameter center electrode wire and insulator tip. Plus, a copper-cored ground electrode runs cooler for extended life. Anti-seize coating on threads. Each sold separately.

 

What a POWERFUL marketing department. Just back fro the HD dealer in vegas with my new $10 spark plugs (2), the GOLD ones. Pulled out my 1 week old Autolight, and put in the new ones. Spark plug socket size was dfferent????? If I dont watch myself I'll be on a new 07!!

 

The ECM is calibrated for the HD plugs. I've tried them all, bike runs better with stock HD plugs. Change every year or 10,000 miles.

Steve

 

Friends don't let friends use Splitfire sparkplugs. Nothing but trouble in everything I have seen them in. Stock HD plugs or NGK gapped down to 39th's.

Joe

 

Some of the platinum plugs will set a code in some of these bikes because of the ion sensing in the ignition system that senses secondary ignition resistance to retard timing when there is a ping detected.

 

The splitfire is not good for HD. I tried in 1340 and 1450 engines. The original plugs or gold for HD work well. The screaming eagle versions are the same than splitfire.
The best plugs are the iridium plugs. You can get in NGK or denso website to know what are the best option for you.
The iridium plugs run more more time without problems. Try

 

Bought my '06 last fall with ~5000 miles. Sounded like engine ping under load. Plugs look OK but looks can be deceiving. Went from Michigan to Florida and have almost 10,000 miles, ready to change my plugs.

What is the NGK number for the '06 EGC, completely stock? Should I try stock HD plugs, and if the ping remains, try a colder plug?

 

Some people just don't get it do they Glide?
Gents....Ion Sense.....resisitance specific to H-D plugs and wires measured by the ECM, an 80 vdc secondary charge sent to the plugs to measure that resistance....if another brand plug or wire has a different resistance value that H-D.....the measurement will report back to the ECM differently. if you have driveability issues...try H-D plugs and wires.......this aint like the oil thing!