Stator CB750 DOHC

Discussion in 'Motorcycle Technical Discussion' started by lwatters38, Aug 17, 2008.

  1. lwatters38

    lwatters38 Guest

    I have a 81 CB750 and I just purchased a new stator for it when I try
    to get it in it is very tight and does not want to seat all the way am
    I missing something is their some trick to getting it in all the way
    or should I consider sending it back I purchased it from Dennis Kirk
    it is made by Rick's Motorsport Electrics has anyone had this problem
    before??????????????????????????????
     
    lwatters38, Aug 17, 2008
    #1
    1. Advertisements

  2. lwatters38

    paul c Guest

    I swapped one from one '82 cb750c to another, I don't remember any such
    problem, but that was more than a year ago and I tend to forget details
    pretty quickly. What'd I do is carefully compare the the new and old
    stators and if I couldn't see a difference, measure them side to side,
    front to back and so forth. Also find a parts explosion diagram to make
    sure I had all parts, fasteners and washers pointing the right way.
    Hopefully, there is no warpage of the case halves etc., if there were
    I'd imagine the old stator might have distorted slightly too and its
    shape might not compare to the new one. Oh, does the old stator slide
    in nicely?
     
    paul c, Aug 17, 2008
    #2
    1. Advertisements

  3. lwatters38

    lwatters38 Guest

    Yea it goes in alittle better but still kind of tight
     
    lwatters38, Aug 17, 2008
    #3
  4. lwatters38

    . Guest

    It's possible you have the wrong rotor, but you'll have to do some
    measuring.

    Compare the internal taper of the old rotor to the new one. It would
    help if you had a vernier caliper to measure the inside diameter of
    the outer hole and the inner hole and the depth of the hole on both
    old and new rotors.

    Alternator rotors are mounted on the tapered stub end of the
    crankshaft.

    The taper is called a Morse taper. The taper of the shaft is about
    half a degree different from the rotor so there is a very tight
    interference fit once the parts are bolted together.

    The Morse taper allows the rotor to be mounted to the end of the
    crankshaft without using a Woodruff key.

    Keys have been known to break and when they break, they chew up the
    shaft.

    Morse tapers are far from a perfect solution. They have their own way
    of chewing up the end of the crankshaft as the rotor "walks" back and
    forth during hard acceleration and deceleration.

    Sometimes motorcycle manufacturers have trouble with the alternator
    rotor slipping on the stub end of the crankshaft, so they change the
    diameter of the stub, which means they have to get their suppliers to
    change the rotor to fit the different sized crankshaft stub.

    Good luck.
     
    ., Aug 17, 2008
    #4
  5. He's replaced the *stator*, not the *rotor*.

    <snip the rest of the irrelevance>
     
    The Older Gentleman, Aug 17, 2008
    #5
  6. lwatters38

    paul c Guest

    I doubt it, since he's already said the rotor was shot aka "shoot" back
    on Aug 14, so it's reasonable to assume he replaced it too.

    He said while he had it apart he'd replace stator and brushes as well.
    Assuming cost is not a big issue, with aged parts that might make
    especial sense, as does the point about the taper, since the two parts
    need to have accurate/consistent spacing between them.
     
    paul c, Aug 17, 2008
    #6
  7. lwatters38

    . Guest

    What would rmt be like, without Old Nell?
     
    ., Aug 17, 2008
    #7
  8. Huh? Stator or rotor? Rotor rotates. Stator is, er, static. Or am I
    missing something here?

    Trouble is, the OP posts a different bloody thread each time.
     
    The Older Gentleman, Aug 17, 2008
    #8
  9. God. Right. Why can't he keep everything in one thread?
     
    The Older Gentleman, Aug 17, 2008
    #9
  10. lwatters38

    paul c Guest

    I think it's alright, repairs have a haphazard way of making one
    thinking the plan is good and then having to substitute a new plan. The
    audience could try sticking to the subject too, at least when it's not
    about political jabs, ie., not for laughs - I'd guess most of us are
    more interested in seeing the bike's problem get fixed first.
     
    paul c, Aug 17, 2008
    #10
  11. lwatters38

    . Guest

    Didja ever stop to think maybe he's hoping to find somebody who just
    wants to *help* instead of a masterdebater?
     
    ., Aug 17, 2008
    #11
  12. He got rather more help from he than he did from you, but wtf.

    Are you going to tell him his bike has two thirds of the weight on the
    back wheel?
     
    The Older Gentleman, Aug 18, 2008
    #12
  13. lwatters38

    . Guest

    If he's as pear-shaped as you are, it does have 2/3 of the weight on
    the suffering rear end...
     
    ., Aug 18, 2008
    #13
  14. Spagethorpe had originally designed the Pariah to work with
    a counter-rotating stator driven by a planetary gear arrangement
    but later abandoned this idea in favor of the higher voltage output
    of a Van de Graaff unit.
     
    Rob Kleinschmidt, Aug 20, 2008
    #14
    1. Advertisements

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.