I have a 2013 CVO Road King (Screaming Eagle 110) and once in a while it will just cough and die at low idle shortly after starting it. Sometimes on startup it will backfire through the intake. I also get a lot of popping from the exhaust on decel (not sure if that is because of the aftermarket slip on exhaust though). I recently noticed that the front spark plug was loose, as in I turned the plug wire and the spark plug rotated with it. The plug doesn't look fouled but I plan on replacing them anyway. Should I replace the wires also? Can a loose plug damage the wire? There is some carbon on the plug just below the wire boot, I assume from blowing out of the cylinder. I'm not sure if the loose plug has been causing my issues or not but that is where I am going to start because tightening the plug back down didn't solve it.

Thanks in advance.

(gratuitous photo of my bike included)

 

Check the terminal on the wire for any corrosion. If it's ok...I wouldn't replace the wires.

 

Would be a good time to inspect the front wire where it hits the front of the gas tank. Lots of wires are rubbing through and shorting on the tank. If the plugs have less than 5000 miles on them, and it doesn't look like the plugs are leaking when the insulator meets the hex area, and the electrode looks nice and light tan, then I wouldn't replace them. I tend to swap front to back sometimes after I inspect them. The rear plug is susceptible to more heat.

 

Clean plugs, make sure top tip is tight, check gap, light dab of anti seize on threads, light touch of dielectric grease on top tip of plug, proper torque plugs, insure good snap fit of cable to plug, and ride that mammy jammy.
If its time for new plugs, do so, but I would go with the above first. Next step if above is not effective, new plugs.

 

X2 except, when I think plugs, I change plugs, or nearly so. They're cheap and I swear there is sometimes something wrong with them you just can't seem to see. I know guys who, regardless of what the manual says with respect to plug replacement, just change em out with every oil change, and swear it makes a difference. YMMV.

 

Thanks for the replies! I do plan on changing the plugs because they are cheap and I don't know if the PO ever changed them, although there was only ~13000 miles on it when I bought it 3 months ago (I've put about 2500 on it since then). The wires look fine inside the boots and the insulation doesn't appear to have any questionable spots, so I won't change them yet.

 

I replaced the plugs, and now she is running better than when I bought her. Thanks again for the tips.

 

A new set of Bosh Plugs, like above, a dab of anti-seize and plug wires are inexpensive to change out, and throw some Injector cleaner in when you fill up : https://www.google.com/search?q=marv...91561428385600
https://www.google.com/search?q=bosc...23923777214711
http://www.harley-performance.com/ha...park-plug.html