Crankshaft hardening

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  • max parsons
    • Jan 2026

    #1

    Crankshaft hardening

    Our local classic racer had his alternator side crank web machined to take a self energizing ignition system but it broke on the first outing.Was this because they didn't reharden the crank?If so can anyone tell us what steel the crank is made of and the best method of hardening it?
  • Nessism
    Forum LongTimer
    GSResource Superstar
    Past Site Supporter
    Super Site Supporter
    • Mar 2006
    • 35783
    • Torrance, CA

    #2
    What is a "self energizing ignition system" and why use such a thing? Lots of Suzuki GS engine race bikes over the years using more conventional ignitions that don't require machining the crank.
    Ed

    To measure is to know.

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    • jknappsax
      Forum Sage
      Past Site Supporter
      • Jul 2003
      • 1108
      • Philadelphia, PA

      #3
      I think he might be referring to a magneto?
      1979 GS 1000

      Comment

      • GregT
        Forum Sage
        • Jul 2009
        • 3541
        • New Zealand

        #4
        Originally posted by max parsons
        Our local classic racer had his alternator side crank web machined to take a self energizing ignition system but it broke on the first outing.Was this because they didn't reharden the crank?If so can anyone tell us what steel the crank is made of and the best method of hardening it?
        Crank web - or the shaft machined ?
        And what motor too please as this makes a big difference. The plain bearing cranks are forgings but the roller cranks are made up of individually hardened pieces....

        If it's the shaft end machined to a different taper for example, I'd doubt if it's a hardening problem, more likely a poor job of blending into the existing shaft size.
        What's the ignition ? What does the rotor weigh ?

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        • Rob S.
          Forum Guru
          Past Site Supporter
          • Dec 2013
          • 9383
          • New York City

          #5
          Originally posted by jknappsax
          I think he might be referring to a magneto?
          Look anything like this?
          1982 GS1100E V&H "SS" exhaust, APE pods, 1150 oil cooler, 140 speedo, 99.3 rear wheel HP, black engine, '83 red

          2016 XL883L sigpic Two-tone blue and white. Almost 42 hp! Status: destroyed, now owned by the insurance company. The hole in my memory starts an hour before the accident and ends 24 hours after.

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          • max parsons

            #6
            I don't know why he is using that ignition,maybe because he can afford it or maybe someone recommended it.It's a German brand.The bike is a 1980 GSX1100{see Stators Travel story}.

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            • GregT
              Forum Sage
              • Jul 2009
              • 3541
              • New Zealand

              #7
              Originally posted by max parsons
              I don't know why he is using that ignition,maybe because he can afford it or maybe someone recommended it.It's a German brand.The bike is a 1980 GSX1100{see Stators Travel story}.
              Probably a PVL. Good ignitions but expensive...small rotors too.

              Hardening the shaft after machining would only make it more brittle. My best guess is that whoever machined it didn't appreciate the loadings and has taken too much off. If it's the type of crank with a bolt in the end retaining the rotor, the bolt should be as long as possible as it actually adds strength to the hollow shaft.

              They're used a lot in the UK i believe - and in the IOM too - so someone there should know how to do it properly. Maybe Trident Engineering ?

              As to why you'd use it which seems to be puzzling our US bretheren....it's a roadracing application. Long races on the IOM and no desire to either carry a battery or run a charging system.....QED

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