owners manual says every 20K

 

I replace mine at 15,000-20,000 miles.

 

I used to replace them every 10,000 miles. Now I let them go to 20,000 with zero problems. They still look great at 20,000 miles. I run Autolite plugs.

 

i haven't changed mine for two years. i do use the harley gold ones, none of the hi tech platinum, iridium, unobtanium crap, just the r12g harley plugs. they work, and are no better than the stock plugs. i will pull the plugs every 10k or so, make sure that the center pin is still flat rather than rounded, etc. check gap and reinstall. don't fall for the gimmick of the iridium or platinum, or especially the split fire screamin eagle types, or the surface gap crap that has four grounds and a center pin. the motors run just fine with the stock or the harley gold.

 

Stock Harley plugs at 10,000 miles.

 

+1 with deluxeroad

 

I have SE double platinum with 30k miles on them and still going...i may change them this fall $15.00 isn't too much of an expense i guess.

 

had to change mine @ 9000

 

Every spring, and don't ever put in new ones without using anti-sieze.

 

I tried the high dollar screamin eagle plugs made bike ping, now I run standard champions from autozone . No problems and no more pinging. I think the screamin eagle plugs were hotter heat range thats why they made it ping. Stick with the stock plug and no problems and way less money.