This guide will show how to remove the old spark plugs, check the new spark plugs for installation, prepare the spark plugs for installation, and reinstall the new spark plugs.

  1. The spark plugs are easy to spot on the left side of the motorcycle.
    • The spark plugs are easy to spot on the left side of the motorcycle.

    • The procedure for removing the spark plugs is the same for both the front and back cylinder, and either spark plug can be replaced first. This guide will show how to remove and install the spark plug in the rear cylinder.

    Aggiungi Commento

  2. Carefully remove the spark plug wire. Do not pull on just the wire, squeeze the spark plug boot, and pull it together with the wire.
    • Carefully remove the spark plug wire. Do not pull on just the wire, squeeze the spark plug boot, and pull it together with the wire.

    Aggiungi Commento

    • Use an 11/16" spark plug socket to unscrew the spark plug by turning in a counter-clockwise direction.

      • Some aftermarket spark plugs that fit the Sportster use a slightly larger 18mm spark plug socket.

    • Remove the spark plug from the cylinder.

    Aggiungi Commento

    • Always inspect your new spark plugs before installing. Check the gap on your replacement spark plugs with a feeler gauge. It should be set to .040 inches.

    • If they are not pre-installed, make sure that the crush washer and terminal nut are installed.

    Aggiungi Commento

    • Using your fingers, install the new spark plug into the socket, and hand tighten until firm.

    • Using a torque wrench, tighten the spark plug to the proper specification.

      • When installing spark plugs, proper torque can be important. To loose and they could rattle out or leak; too tight and you can strip your cylinder head. The correct torque for this plug is between 90 and 120 inch lbs.

    Questions.1 with a stage 1,2 or 3 would you agree a wider gap? 2nd question which is simular to first.i do run my motor a little rich.rather rich than question is with modification on a harley davidson sportster.what do ou many choices from om to iridium to platinum.then the gap and also are you a believer in cutting the eledtrode approx half off for max much would you recommend cutting and back to og question.the a larger gap.capable of power increase.since ive tried both i swear i feel a power increase.but is it anticipated or other varibles???you opinion is valued.

    Joey zero - Replica

    • Reinstall your spark plug wire by pushing it firmly onto the new plug.

    • Make sure that it seats properly. You can usually feel a definitive click when it is installed correctly.

    I have a Harley Davidson Xr1200x Sportster which I just got. Changed the oil also tranny & filter as I couldn't find last date of service coang of oil. So yesterday I checked the spark plugs they were clean. But the mechanic cleaned them & said the needed gap them as one was too narrow. Mind you I had no issues at all. Gapped them at 0.40 now I'm not getting the same smooth sound or feel as if it's miss firing. I have iridium spark plugs okn my bike should I change them to NGK or get another set of iridium spark plugs.please advise..

    Steven Sewell - Replica


Be sure to repeat the above procedure for the remaining cylinder.

Altre 14 persone hanno completato questa guida.

Eric Essen

Membro da: 04/06/2010

15.815 Reputazione

8 Guide realizzate


iFixit Membro di iFixit


114 Membri

6.995 Guide realizzate

Just for information, particularly in the UK, you may be able to purchase sparking plugs cheaper at a Chandlers, as there are quite a few 4-stroke outboard engines use these plugs.

BigRoj - Replica

How do you do this with a XL1200S with dual spark plug heads??

Andy - Replica

Couldn't have made it any simpler

Matt Pramik - Replica


- appreciated

Thank you so much for your posting. I'm 2k miles from my daughter who is teaching herself how to maintain her own bike. You site is immensely helpful and appreciated as much.

mrjacecabezut - Replica

Aggiungi Commento

Visualizza Statistiche:

Ultime 24 Ore: 9

Ultimi 7 Giorni: 90

Ultimi 30 Giorni: 458

Tutti i Tempi: 40,041