Norton Racing Cylinder Coolant Seal – Kawasaki Ninja 400 / Z400


***Highly recommended as a preventative measure for ALL Ninja 400 race/track bikes***



The Kawasaki Ninja 400 and Z400 have a problematic coolant seal between the cylinder and case on the front of the engine.  This poorly designed OEM seal has a tendency to fold over or deform over time, causing a coolant leak on the front of the engine that is labor intensive to fix since the cylinder head must be removed.

After replacing numerous OEM seals in race and street bikes, we have designed and manufactured our own Norton Racing seal to replace the OEM seal.  Our Norton Racing Cylinder Coolant Seal features a machined aluminum body to fill the OEM seal location and dual o-rings captive on top and bottom to eliminate potential failures.  Highly recommended as a preventative measure in all race bikes and recommended as a replacement for the OEM seal in any case (Track or Street bike) where the OEM seal has failed and must be replaced.

Additional information

Weight .1 lbs
Dimensions 6 × 6 × 6 in


  1. Ryan Vallieu (verified owner)

    This should be the standard Kawsaki design! It’s a bit of a pain to fit, but that isn’t Norton’s fault. It requires cam removal, head and cylinder removal and thus coolant draining and making sure the timing is correct upon assembly. Standard stuff.

    But THANK YOU for making a viable solution. My bike hadn’t started leaking yet, but the oem seal was already deformed when I got a look at it.

    Swapping the seal itself is the easy part of the operation 😀

    No leaks! Upon firing up the bike and running through some heat cycles.

  2. Jason M Borowski Jr (verified owner)

    Fixed my leak! Every ninja 400 will need this at some point. Should be factory. Easy job if you have the service manual for a basic mechanic. Was my first job and it went smooth.

  3. Eric (verified owner)

    Great solution! Got mine and installed while doing my first valve adjustments. Pretty easy, just time consuming. Pretty much a guarantee you will need this at some point. Let Kawasaki know when you do! They should buy out the patent, give Norton some well deserved mula, and provide their customers an expected experience.

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