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2011 ZX-10Rs Getting New Camshafts, Valve Springs and Spring Retainers Before Sales Resume in Late January

We just received the following press release from Kawasaki concerning the technical hold placed on the 2011 ZX-10R.  Kawasaki reveals the problem to be “possible surging of the intake valve spring”.  Here is the release:

IRVINE, Calif. (Dec. 29, 2010)—Kawasaki Motors Corp., U.S.A. today announced that the recent sales hold placed on the 2011 Ninja® ZXTM-10R sportbike is expected to be lifted in late January and that sales of the highly-anticipated unit will resume as normal.

 According to Kawasaki engineers, the proactive sales hold resulted from a finding that indicated possible surging of the intake valve spring when the unit is operated under unique riding conditions, such as on a racetrack.  The surge could cause the intake valve to seat improperly, resulting in poor engine performance.

The camshaft, valve springs, and spring retainers are being replaced to prevent the valves from surging, without affecting engine performance.


  1. Zuki says:

    “Who says a bucket-tappet I-4 has to be slow?”

  2. azi says:

    Would desmodromic cams get around this problem?

    • Norm G. says:

      i think you mean just to say desmodromics (actuation). and the answer is YES, but so can a spring assuming properly spec’d, designed, and manufactured. but nobody, not even K-heavy make every little bit. most things are subcontracted/outsourced. this recall (after the fact) hints at a typical supplier problem. as they say, “if i had a nickel for everytime i was shipped the wrong part”…?

    • Zuki says:

      I say just buy a Ducati if you want lever-tappets but some people say bucket-tappets are the answer for pushrods so what’s wrong with Kawasaki using bucket-tappets on their inline four? I say metallurgy is where it’s at. Go figure.

  3. Mike B. says:

    It’s the Slinky effect! Great video Werner…

  4. Werner says:

    The following forum posting is well worth reading.


    They use the terms value surge and valve float interchangeably. The video at 1000 frames per second is amazing to watch. It shows how a healthy vs a worn spring reacts under load. This might shed some light on what happened inside the 10R’s engine, if the inlet valve springs were not strong enough and started to resonate at high RPMs causing valve surge/float. This is not my field of expertise, just passing along information that my friend Mr. Google helped me to find (smile).

    • Norm G. says:

      and there you have it. the end game of all this is to simply ask the question, is or is not the valve resting on the seat when it’s supposed to be…? (ie. following a given cam profile at all rpms).

  5. Dean says:

    Happy New Year guys! Love the site!!

    By the way, Valve Surge was the name of my band in high school.. We also kinda floated at high RPM.

    • MGNorge says:

      I think Kawasaki acted swiftly enough to the situation, at least before most even knew there was an issue. It even sounds like a potential BIG issue, one that might only show up on the race track. So in reality, going by what little has been said, most owners might never notice a problem. But to replace engines is drastic so they must feel the problem is keen enough to take it swiftly out of dealer’s hands and put the tag of “valve surge” on it which doesn’t compute in most minds. I think it lessens the severity to those hearing it but I think the issue is greater. I think that unless Kawasaki took corrective action they would have had some engines grenading, if only on the track. That isn’t the kind of PR any company would want when upholding their performance image and defending their crown.

  6. Bob says:

    Good Grief! Who cares? The bike will make 20 hp less in the U.S. in order to comply with stricter noise restrictions that those in Europe. BMW has nothing to worry about.

    • Norm G. says:

      lets hope the 20hp less turns out to be a good thing…? even without an economic downturn, i’d like to think the “arms race” will come to an end by one factor or another. if the recent OHV laws, CARB laws, and Arnie’s forthcoming noise law are anything to go by…? if the manufacturers don’t self-regulate (self-terminate anyone?:)), the idea of 200hp/200mph bikes (which we’re kinda already at) on the street will eventually show up in the crosshairs of some law maker.

      • Justin says:


        (there you don’t even have to click through to get the joke)

      • mrbill says:

        I am an engineer for a company that makes GPS tracking systems for fleet vehicles and I can tell you that law’s like Arnie’s are the least of our worries. They day will come will all vehicles will be monitored continously. The technology already exist and isn’t very expensive. Big Brother will know every move. There won’t be a market for anything that goes over 80mph, much less 200.

        • Norm G. says:

          the OTR driver’s eye in the sky. qualcomm anyone…?

        • Tom Barber says:

          This is the way it should be, because the idea that individuals should not be constrained by public laws, when on public roads, is preposterous at face value. It is curious that this is not manifest to everyone. When people think that they are in the safe confines of a peer group that would likely agree with comments that are tantamount to anarchy, they will often make comments of that sort, which they would not make in other circumstances where the peer group has a different make up. I myself have probably done this on a few occasions.

          Since back in the ’70s when the nationwide 55 mph speed limit was first enacted and the de facto speed limit was at least 10 mph higher, I have believed that if the speed limits were rigidly enforced, the public would demand that the speed limits be set to the higher, realistic level. When the legal speed limit is well below the de facto speed limit, the notable consequence is that drivers are punished for the number of miles that they drive, as much as for how much their typical speed exceeds the typical speed for the population as a whole. Once an individual gets into that situation, it shows up on their driving record and is visible to judges and to law enforcement. That individual will thereafter find it very difficult to avoid a ticket once pulled over, or to be granted any leniency by any judge. Their insurance rates increase, and they are forced to drive significantly slower than what is typical for the population as a whole, because their offense is not that they drive faster than everyone else, but is rather than they drive more than everyone else. This is not a desirable situation, but this is exactly what is guaranteed to happen if the legal speed limit is set below the de facto speed limit. And as long as people believe that they will get away with speeding 95% of the time, they will not care much about whether the legal speed limit is set below the actual speed limit. This is a deplorable situation. It stinks to high heaven, and it is a sad commentary on a society that they would tolerate this situation.

          In order to avoid this sad situation, it is absolutely essential that speed limits be rigidly enforced, such that hardly anyone ever gets away with speeding. Only then will the public insist that the speed limits be set realistically.

          The best way to insure that speed limits are rigidly enforced is to install automatic monitoring in all vehicles. I would be in favor of this, but I doubt that it will ever happen, because of the fear of Big Brother. The population as a whole, when given a choice, prefers a legal system that is not enforced to the letter of the law. The population as a whole is so afraid of the Big Brother state, that the alternative that they prefer is the alternative where the legal speed limit is not strictly enforced. They prefer this alternative even though with this alternative the detrimental effects do not derive from mass paranoia, but rather from the hard reality of what occurs when speed limits ordinarily and routinely are set, and are expected to be set, significantly lower than the speed at which most people drive.

    • MikeD says:

      Lol, that was their FIRST STRIKE…this valve spring “surge”=”float” issue the second one. What’s next…? Taking bets now…

  7. Bud says:

    For those who didn’t take the time to do any internet research:

    Coil surge is a scenario that takes place when the spring is set up to far away from coil bind giving the middle coils room to bounce back and forth from top to bottom as the spring is closing. This usually takes place with a highly energized spring (fast ramp rate) at high engine speeds. Having a spring with not enough rate can exacerbate the problem and having a spring with both too little rate and not enough seat/nose pressure in conjunction with being set up too far from coil bind is down right deadly. This will cause valve bounce similar to floating the system and letting the valve hit the seat.

    Kudos to Kawasaki for identifying a problem and fixing it before they had parts failing and upset customers to deal with.

    • Justin says:

      Bud, thanks for clearing that up.

      This is starting to sound like a design issue, not a quality issue, i.e. it’s not that the parts are not manufactured to spec, but that the spec itself may have been too aggressive. if there’s an industrial engineer who disagrees with my definition of ‘design’ vs. ‘quality’ I’ll accept correction 😉

      If that’s the case, I’d say Kawasaki is guilty of hastening their development process in order to get a competitor to the BMW on the market. After all, it is their reputation as the peak HP king on the street that BMW is challenging.

      After they recognized the flaw, I have to give them credit for their efforts to recall the bike. It seems like the engineers probably won that argument, since they started buying the bikes back /before/ the corporate mouthpieces could decide what to tell everyone.

      • jimbo says:

        Justin wrote: “…it is their reputation as the peak HP king on the street that BMW is challenging…”

        IIRC BMW owned the HP battle since the arrival of its 1000 race-replica. All comers since that time are the challengers, not vice-versa as implied above. To the extent someone perceives Kawasaki is the street bike HP king since BMW’s 1000 arrived, their perception is inaccurate until objective independent testing proves otherwise.

        I have no so-called “dog in this fight” and could not care less the HP king. The last time I rode a 150+ HP bike (weighed considerably more than modern open class race replicas) I was cured of hunger for such acceleration potential.

        • Justin says:

          I guess my definition of the word ‘challenging’ is also subject to review.

          Frazier beat Ali once, too. (Technically, Frazier was the champ already, though Ali never technically lost the belt. Or maybe it’s that Ali technically lost the belt, but never actually lost the belt. So let’s not get too technical.)

          I’m not prognosticating. Kawasaki has held this position for a long time, across several model ranges. The other Japanese manufacturers have, to my eyes, long since conceded that their bikes will make less hp than the competing article from Big Green. I’m sure if you asked somebody at Kawasaki they would say that they were still the hp kings. Ditto BMW.

          My hypothesis is that this is the reason why the new ZX-10 may have been rushed to market too hastily; there is an unresolved conflict and Kawasaki wants to be the winner. It would have been better had you addressed this hypothesis (which is still just a steaming pile of speculation) than the simple semantics of my use of the word ‘challenging’.

          Perhaps, as you posit, BMW is now the champ. But it’s certainly not a unified title, and it’s only in one weight class. Kawasaki is entitled to a re-match and it’s my opinion that one fight does not a champion make. While I no longer enjoy watching men punch each other in the head, I will enjoy watching these horsepower ‘fights’ get played out in the media and on the dyno.

          Obviously, we both do have dogs in this fight. but they’re the little annoying yappy dogs that don’t do anything. it’s ok man, i’m right here with ya

  8. MikeD says:

    Kawasaki should have stepped into the spotligth and take it like a MAN, say it str8 out what it was and how is being fixed (DETAILS, DETAILS !! WE AIN’T DUMB, most of us anyways, im pretty sure we could understand most of the Technical jebrish).
    The (SHADY)way they handled it im my eyes it made more harm than good, u know whats being said: “No second chance for first impressions”.
    Glad they corrected it, but they are scatted on “my eyes”, JMO.

    • Old town hick says:

      Wow, I didn’t know Kawasaki was so EVIL. A regular Darth Vader of the motorcycling world.

      Thanks for setting us all straight MikeD.

      • MikeD says:

        LMAO, ok ok, maybe i over did it a little too much… LOL. I made it sound like an EPIC proportions thing. Man, i gotta slow down…LMAO.

        • Old town hick says:

          OK, that’s cool.

          Now let’s all turn our attentions to some of the seriously troubling concerns for 2011, like nationalized healthcare and the Oprah Winfrey Network.

  9. Bob says:

    I don’t think valve surge is the same thing as float in this case. If it was, all that would be needed is heavier springs. As they are changing the cam shafts, I can assume that the intake closing ramps were designed way too steep. The reason to do this is the intent of having more duration at max lift rather than increasing total intake duration to achieve the same thing with a more reasonable profile. Unfortunately this allows the spring pressure to slam the valve shut at near full force rather than follow the cam profile which would guide the valve closed in a controlled fashion.

  10. Paso100 says:

    I can see the headline: “Kawasaki gives (new) head” lol.
    From what I’ve read elsewhere, valve surge is not floating, but instead vibrating against the valve seat at higher rpms, causing loss of power. Why this is happening is anyone’s guess. Is Kawasaki putting in a different profile camshaft? I suspect a metallurgy problem with the springs also. Why don’t they just be completely honest and tell their customers the cause? Because it would point to quality-control issues, that’s why. Now they’re just causing more marketing problems for the future. Dumb move, following in the footsteps of Toyota it seems.

  11. Norm G. says:

    i could be wrong, but it sounds like the term “surge” is just a typical translation anomoly that occurs quite often when dealing with a foreign company (in this case japanese). i don’t think we can assume the terms “surge” and “float” are defined seperately in the japanese lexicon the way they are in american lexicon.

  12. BlueSkyGuy says:

    Likely to effect engine power in the top end keeping valve springs lighter makes for better HP but can back fire in this way. Face it at this level every gram counts for some small degree of power. Kawasaki has come to the table early to fix this issue which speaks well of how they want to be viewed in this segment, others have released motorcycles and tried to fix the problems in the field at the suffering of the customer.

  13. Vrooom says:

    I think squid-boy is right, sounds like floating valves to me to. Valve surge, I’m trying to imagine what that is. Everyone’s familiar with a surging bike due to excessively worn chain or poor injection, but valve surge?

  14. Squid-Boy says:

    Just sounds like good-ole-fashioned valve “floating” to me.

  15. Honker says:

    So it sounds like the cam was to aggressive for high RPM’s, resulting in the valves being shot into the cylinders, and the springs were to weak to pull the valves shut.
    I was wondering when the Jap bikes had to go to desmo valve operation.

  16. Steve says:

    Valve surge? What the hell is that? It’s a new one on me.

  17. MGNorge says:

    Valve surge? Affecting engine performance? Sounds like affecting engine health!

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