ZX-6R Maintenance: Service Spark Plugs


I am not a mechanic or a representative of any motorcycle or tool manufacturer or anything else official. This page is only my notes on doing this procedure myself. Although I believe what I have documented here is correct, I make no promises and you do this at your own risk.


Servicing your spark plugs is part of the regular service schedule for your bike. At the specified intervals, you should clean or replace them, and check the spark gap size.


Tools Required

  • Rear stand (recommended)
  • Phillips screwdrivers
  • Hex wrenches
  • Metric sockets.
  • Spark plug socket (the one from the bike tool kit will do)
  • Torque wrench
  • Spark plug gap gauge or feeler gauge

Supplies Required

  • New spark plugs or cleaning equipment

Difficulties & Warnings

Some difficulties could be:

  • Over-tightening when re-installing the plugs. Use a torque wrench.
  • Cross-threading when re-installing the plugs.
  • Breaking a plug by trying to use a regular (non-spark-plug) socket.


Putting the bike on a rear stand makes this job much easier by levelling the bike and holding it steady.

First you must

  1. Remove the seats
  2. Remove the gas tank
  3. Remove the air filter assembly
  4. Remove the carburetor assembly


After removing the carburetor unit, the engine cover is exposed.
Each spark plug has a coil over it, with an electrical harness connected. Disconnect the electrical harnesses to all 4 plugs. (Number them with a silver or white felt pen first, so you can reconnect them in the right order, which is critical.)
Pull out the various vacuum hoses that are cluttering up the space on top of the engine head (label them so you can put them back properly later).
Pull out each of the 4 coil assemblies over the spark plugs. You just wiggle them and pull up firmly and they will let go. Either number them first with a light felt pen, or service and reconnect the plugs one at a time so you don’t get the order mixed up.
Insert a long spark plug socket, like the one in the bike tool kit, into one of the holes,
and unscrew and remove the spark plug.
Replace the old fouled plug (left) with a new one; or clean the old one with a suitable cleaning tool. (For the few dollars, I replace them.) Check the gap against the manual’s specs (mine specified 0.7 – 0.8 mm).
Re-install the new plug, being careful it goes in the hole straight, without cross-threading. Use a torque wrench to avoid over-tightening. My manual specifies 13 Nm113 inch-pounds torque for the spark plugs.


  1. Thank you for tutorial w pictures. Very helpful!
    I would like to do a compression test on my ZX-6. I have a compression tester but it has a larger thread size for ck auto compression.
    Can you plz advise of plug size, thread info.
    Thank you, TYVM

  2. I changed my plugs on a UK zx6r j2 today following your instructions. It gave me the confidence to get stuck into doing my own maintainence thank you.

    I was able to just remove the lines and the vacuum chamber with out the need to remove the carbs at all. Just pulled the electric connectors off the coil, broke the seal around the bottom of the rubber on the coil stick. Popped out the coils. Then used the plug wrench that came with the bike. Really easy actually.


  3. hey thanks for all the pointers.

    My bike came without the socket tool, do you know what size plugs are so I don’t have to buy and try a bunch of different sizes?


    1. Sorry, I don’t have that bike any more so I can’t measure it. (Buy your replacement plugs first & then measure them.)

      From memory, though, I think it was a 16mm socket (remember these bikes are metric). That’s just a tiny bit smaller than a 5/8″ socket, which would probably do – but I’d go a long way out of my way to get the metric one.

  4. Most important thing on here is the torque marking for the plugs
    Its 113 inch pounds not 113 foot pounds read the marks on your torque wrench
    Carefully, or you can and will damage your engine severely

Leave a comment

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.