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M8 EFI to Carb conversion

  • speedzter
    speedzter
    4 hours ago
    I found this a while ago, and thought it would be handy for my M8 powered FXR daydream !
    I had previously looked at their Twin Cam EFI/Carb setup when I was doing the 
    VW beetle to Twin cam engine conversion .

  • John.R
    John.R
    3 hours ago
    Altmann make good quality gear. Their standalone system for twincam is much much better than the Thunderheart system people always talk about. That thing is basic as fk and a step back from an Evo ignition.


    Biggest issue with M8 conversion in FXR is the extensive frame mods, but more n more products are coming out to overcome that hurdle, like weld in motor cradles etc.
  • Hilly
    Hilly
    1 hours ago
    Don't bite me here, this is just a question, could you do this to a twin cam and get it registered? 
  • speedzter
    speedzter
    1 hours ago
    Do you mean a legal Carb conversion ?
    Technically you would need it to be engineered and pollution tested.
    But in reality, I don't think anyone would know the difference .

    The Altmann supplier is german based, and they are quite strict, but can get away with it if it tests OK .

    Have a look at their little device to aid pollution testing:
    http://www.altmann.haan.de/L1/
  • Hilly
    Hilly
    1 hours ago
    Quoting speedzter on 29 Jan 2026 03:08 AM

    Do you mean a legal Carb conversion ?
    Technically you would need it to be engineered and pollution tested.

    But in reality, I don't think anyone would know the difference .

    The Altmann supplier is german based, and they are quite strict, but can get away with it if it tests OK .

    Have a look at their little device to aid pollution testing:
    http://www.altmann.haan.de/L1/

    Well bugga me! It's a calibrated intake manifold leak 😁
    I'm going to save these links, could come in handy down the track, thanks 👍
  • speedzter
    speedzter
    1 hour ago
    Quoting John.R on 29 Jan 2026 01:12 AM

    Altmann make good quality gear. Their standalone system for twincam is much much better than the Thunderheart system people always talk about. That thing is basic as fk and a step back from an Evo ignition.



    Biggest issue with M8 conversion in FXR is the extensive frame mods, but more n more products are coming out to overcome that hurdle, like weld in motor cradles etc.

    I ended up using the Thunderheart Ignition, it was a fair bit cheaper .
    I'm not sure the Altmann is better , they both have adjustable Ignition curves and don't use a MAP sensor .

    The Thunderheart at least is programmable with windows software :
    https://thunder-heart.com/Tech%20Service%20PDFs/EI5011.pdf
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