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Wednesday, November 3, 2010

Switchable Power Modes Part II

A member on an enthusiast board had some questions and comments about my power mode switch. I thought I would repeat our conversation here... maybe it will be informative to others.

Warren's words in italics:

So... Looking at your blog, it appears that the VFR is doing what so many other high power motorcycles have done in the past with restricting the lower gears to prevent early termination of it's riders. Namely, the GSX-R and the 1000RR.

That's my best guess. I've pondered about the restriction being some sort of mechanical failsafe, but I really don't think that's the case.

Both of these bikes have products that do essentially what you do with your switch, however they have "smarts" built into them so that the instrument clusters continue to read the correct gear.

For example, Ivan's make a smart TRE:


The company that make the speedo healer has the X-TRE:


But more interestingly, Bazzaz has a product called the Z-Bomb:


But as far as I can tell when looking at the installation instructions, it attaches to the Throttle Position Sensor. What are your thoughts?


Thanks in advance,


The wiring layout in the VFR1200 makes it difficult to avoid the gear indication error when the bike is in de-restricted mode. There are 7 individual gear position wires which run directly from the gear position sensor into the ECU and transmit 7 individual gear signals. It's simple, so it's easy to hack. After that it gets tricky. The ECU interprets those individual signals, decides what throttle and ignition map to use, and then encodes it and sends an encoded digital pulse signal through a single wire on the serial link to the combination meter (instrument panel) to be displayed on the gear indicator. To get an accurate indication on the gear while in de-restricted mode, you would have to decode the serial link. I think that's what Ivan has done with his Smart TRE chip for the gixxer. It's a complicated solution. It can be done, but it would take some work and savvy computer skills. On a bike like the Gixxer with its enormous market base, it's worth it for someone like Ivan to put in the time. With very few VFR1200s on this side of the pond, it's hard to imagine anyone bothering.

The Z-bomb is a little different. Honda programmed the American market 08 CBR1000RR to retard the timing at high RPM at full throttle, robbing it of 7 or 8 peak horsepower. It was suggested that this was to pass noise tests which are measured at a percentage of maximum RPM at full throttle. As far as I can tell, the Z-bomb tricks the ECU into thinking that the throttle isn't fully open, therefore allowing the full ignition advance and replacing the stolen horsepower.

The Gixxers and CBRs use a timing retard to limit power, but I still think that the VFR is limiting power through its "throttle by wire". (which the GSXRs and CBRs don't have yet) If I'm correct, that would mean that there are 2 throttle maps, one restricted and one unrestricted. The ECU is interpreting the gear position signals and telling the throttle valve motor which map to use. The gear position sensor is a crude but effective bypass.

There may be a more elegant solution but I'm just not smart enough to crack it. Studying the wiring diagram, there are a pair of wires which I suspect may contain the answers. There are 2 wires that run from the ECU to the TBW motor labeled TBW MTR+ and TBW MTR- on the throttle valve side, and labeled TMOM and TMOP, respectively, on the ECU side. If my hunch is right, these could be the wires that send the throttle map signals. My guess would be that TBW MTR- could transmit the restricted map. If that were the case, you could cut that wire and splice it to the TBW MTR+ wire so that the throttle valve motor never recieves the restricted map.

Again, I'm just guessing... and I don't want to be the guy to test it. If I'm correct though, this type of mod would de-restrict the bike without giving a false reading on the gear position. A switch could be installed easily with this mod as well.

I just need somebody smart to review my theory. Where's that Dutchgixxer guy?

Here is the wiring diagram and the wires I'm referring to. The wires I'm talking about are circled in red:

Edit: TMOM and TMOP appear to be the power supply for the throttle motor. (wires A9 and A10 coming off the ECU. Cutting or altering them will cause the throttle motor to quit. Not advised. :)


  1. Thanks for the response... If only the VFR were a slightly more popular bike all around, we'd have our answer a lot sooner.

    Talking with the guys at Dyno-Jet, they're struggling getting the Power Commander to the market for the VFR due to an entirely new ECU to FI setup that the bike uses. I guess the harness to the injectors doesn't behave like other bikes and they're not getting much help from Honda.

  2. The trottle valve is operated by a closed loop servo system. The ECU reads the trottle valve position it is compared with its desired position.
    The disired position is calculated from trottle position, wich gear is selected and vehicle speed. If there is a diffence ( error ) a correcting action is taken. Eg the trotle valve position is adjusted by the ecm. The 4 wires are the 2 motor wires and 2 wires to measure the current trottle valve position. If one of the wires is cut or moddified the trottle by wire is not working any more. So do not mess with the closed loop servo.

    Btw i am busy decoding the "serial link" to the combined dash indicator. to be continued.

  3. Hello,

    I'Am french. Can you send me the wiring diagram of the 1200 vfr. Do you know the difference between the europeean/us wire ?
    Otherwise, can you also send me the ECU US price ?

    Good bye, thanks in advance.

  4. Your French bike must be restricted to 100ch? What a stupid law... The wiring diagram is shown in the last photo of this entry. It's a high-res file so it can be expanded quite large. I don't know the difference between US and european wiring, and I'm not sure what method they use to restrict the French bike but I expect that a replacement ECU would do the job.

    The American ECU is part number 38770-MGE-773 and can be ordered here for $761.05 USD:


    My wife and I visited France on our honeymoon in 2009. We spent time in Paris and Marseilles. What a beautiful country... I'd love to ride my motorcycle there.

  5. Hello,

    Thank you very much for the informations.
    The method to restrict French 1200 vfr is the
    ECU (for 100ch) and there is a restriction for the rest of Europe (Allemagne/Italie/Spain...) to 250km/h with the ECU ED. HRC sell ECU-US with a litle change in the wiring for de-restrict the 1200 vfr (only to use on track).

    If you want go in France, I'll be pleased
    to receive you (you and your wife). We live 120kms south of PARIS.

    See you soon.

    Good Bye.

  6. Digging up an old post I know, but looking at that diagram it looks like the Instrument Cluster shouldn't be TOO difficult to hack. It looks like each function/light/indicator on the cluster has it's own dedicated wire. If we pulled the TXD wire from the cluster, my assumption is that everything would work with the exception of the gear indicator. There is no RXD line on the instrument cluster so it's an open loop system and the ECU shouldn't notice the change.

    If that turns out to be correct and all other gauge functions still work we should be able to put together a small micro-controller to determine the proper gear and push the data out onto the SCI bus.