The trouble with North American ZX-10Rs

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This dyno chart shows the difference between a stock, North American 2011 Kawasaki ZX-10R and one that’s had its ECU told to stop restricting throttle openings at high RPM. Both measurements include the same slip-on exhaust canister. Courtesy of Speed Tech Motorsports, this dyno chart is the best illustration we’ve yet seen of the effects caused by Kawasaki’s attempt to meet EPA noise regulations. Stock ZX10-Rs for other markets are rated at 197bhp (at the crank), while North American bikes are rated at 176bhp.

Speed Tech reports that, on it’s relatively conservative Dynojet, the completely stock bike was putting out 164hp at the rear wheel. To achieve 180hp, they fitted a Hindle slip-on and modified the stock ECU program to allow full power past 11,500rpm. In this configuration, they say the engine is still running lean and expect even better results with the fitment of a Power Commander.

It’s been officially stated that Kawasaki made changes to the exhaust can and ECU on North American bikes in order to meet the EPA noise regulations. They’re not the first manufacturer to be forced to do so, but it does appear as if the ZX-10R has had its power reduced the most dramatically. Changes, by all accounts, are not made to the engine itself, meaning obtaining full power is relatively easy, as demonstrated here.

Speed Tech via WERA Forums

  • Miticale

    I’ve never delved into the technical details of it, but aren’t the BMW’s restricted power wise as well? Not sure if it was the manufacturer making the call, or for EPA regulations.

  • Mike Brooklyn

    So whats the full cost to get it back up to spec if you buy a US one?

  • BeastIncarnate

    That’s a pretty smart way to meet regulations, if they’re forced to. It’s the easiest to circumvent.

    Still, it sucks that it’s necessary.

    @Mike Brooklyn – I’d expect full cost to be a Power Commander, unless the modified can is making a significant difference. Best case is $300-$400. Worst case is upwards of $1000.

    • Case

      I think it’ll be closer to $1000, depending on which slip-on exhaust you get. I don’t think you’ll be able to get the full mojo from a PC alone; I expect there to be too much restrictive lameness in the stock slip-on.

      • fasterfaster

        Nah, they only need the PC to compensate for the slip-on. The mod with stock exhaust is just a reflash of the ECU. Should be $100, labor only. No parts. You can probably even talk the dealer into doing it for free at time of purchase.

    • Mike Brooklyn


  • JaHo

    US noise regulations are actually less restrictive than their European counterparts. I’d be interested to see back-to-back dyno runs between a Euro-spec and a US-spec bike. Making comparisons between tuned and stock bikes tells you what the bike is capable of, but isn’t an apples-to-apples comparison.

    Both have a similar procedure- in a controlled environment (low wind, flat surface, no obstacles around to reflect sound,) you accelerate past a microphone hooked up to the sound meter, and the meter measures the maximum sound level. Repeat a bunch of times on the right and left, do a bit of simple math, and you get your reading.

    The European test, however, places the microphone half as far away from the bike, making it twice as loud (about 6dB). Both tests specify a maximum of 80 decibels (A-weighted.) 6dB is a lot.

    The reason for the cut in power at high RPM is that, per the regs, the speed you go through the test is calculated as a percentage of the RPM where you make max power. So moving the max power down in the rev range lets you go through the trap slower, at a lower RPM. This makes less noise and makes the bike pass the test.

    The European bikes are likely even less powerful than the ones we get in the US.