92 Yamaga Seca II starter clutch

Discussion in 'Motorcycle Technical Discussion' started by trev bachelder, Feb 25, 2005.

  1. How do you get at this part for replacement? Do you have to split the cases
    or is it accessible after the side cover is removed?
     
    trev bachelder, Feb 25, 2005
    #1
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  2. the cases or is it accessible after the side cover is removed?

    I feel your pain, Trev, I don't relish the thought of having to split
    my FZR-1000's cases if the starter clutch goes out, but it is
    absolutely *buried* inside the engine, it's the last thing you can get
    to...

    On the plus side, it gets lots of engine oil to lubricate its
    bushing...

    http://216.37.204.202/Yamaha_OEM/YamahaMC.asp?Type=18&A=46&B=16&Action=O

    Parts # 8, 9, 13 are the guts of the starter clutch...

    It spins on Part @14, a shaft...

    Part #3 is the starter chain that goes around the center of the
    crankshaft.

    http://216.37.204.202/Yamaha_OEM/YamahaMC.asp?Type=18&A=46&B=5&Action=O

    Do you see that sprocket in the middle of the crankshaft? That's the
    camshaft chain sprocket. The thing that looks like a gear next to it is
    the starter chain sprocket...

    Kawasakis and Suzukis do have the starter clutch bolted to the back of
    the alternator flywheel, but the starter clutch in your Seca probably
    shares the same part numbers as Yamaha's FJ-1100, FJ-1200 and FZR
    models with the buried starter clutch...
     
    krusty kritter, Feb 25, 2005
    #2
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  3. The part that appears to be worn is not the bushing, but the actual
    engagement teeth in the clutch portion of the mechanism. I can't believe
    they would make it so difficult to get at a "normal wear" component that
    will inevitably need to be replaced from time to time. Granted, the bike is
    getting a bit old, but the rest of the engine is in great shape. Normally,
    if you had to split the cases to repair anything on a bike this old, you
    would automatically do a rebuild on the engine while you had things apart
    (i.e. rings, valves, bearings, etc.). But in this case, none of that is
    really needed, so the labour portion of the cost is way out of proportion to
    the cost of the starter clutch parts. Damn!!
     
    trev bachelder, Feb 25, 2005
    #3
  4. The typical centrifugal starter clutch doesn't have any teeth. But that
    shaft I pointed out and some parts on the shaft do have spline teeth,
    which aren't the same thing as gear teeth. I can't say for sure whether
    the splines are worn out, though, or if the starter chain has broken or
    slipped away from contact with the sprockets that it is supposed to be
    on...

    I have a Haynes manual for my FZR-1000. It shows that I can remove the
    stub shaft and *part* of the starter clutch, after removing the
    alternator, which is driven off that same stub shaft, by the starter
    chain, but I would never get the idler gear out of the engine without
    splitting the cases. The idler gear is under that big hump in the
    center of the top case...

    Back in the early 1980's, Yamaha was building big-bore engines with
    *car-type* alternators that were behind the cylinder, under the carbs,
    and the starter had to be moved from the position where it had been so
    the alternator could fit there. Beyond having the more reliable
    car-type alternator, Yamaha also wanted to get the alternator off the
    end of the crankshaft to make the engine narrower so the bike could
    lean over without dragging the alternator cover. A sinister side effect
    was that the starter was moved farther toward the rear of the engine...

    When Yamaha designed the Seca II, they didn't want a car-type
    alternator, the engine is fairly narrow, and a small permanent magnet
    type alternator on the crankshaft was good enough. But the starter was
    left back at the rear of the engine, with that silly stub shaft and a
    long multiplate chain. What is really ridiculous is that the chain is
    turned by the crankshaft *continuously* at high RPM, even though you
    aren't using the starter all the time...

    The idler gear just sits there on that spinning stub shaft, with a
    bronze bushing that fortunately gets lots of oil acting as a bearing
    for it...

    At least on the FJ-1100 and FJ-1200 and the FZR-1000 series, that chain
    drives the car-type alternator which does need to be turning all the
    time...

    The centrifugal starter clutch has 3 large cylindrical rollers. They
    are about 1/2 inch in diameter and about 1/2 inch long...

    Each roller has a small spring and a short pusher that forces the
    cylindrical roller down against a large diameter cylindrical section on
    the idler gear part of the centrifugal starter clutch. That part is
    about 2 inches in diameter and 1/2 an inch wide...

    When the engine starts, the three cylindrical rollers are forced away
    from that cylindrical section. They roll up three radial ramps, and
    centrifugal force holds them away from contacting the cylindrical part
    of the idler gear...

    When you shut the engine off, you will normally hear a whiz-ching!
    sound as the three rollers drop onto the idler gear's cylindrical part.
    The starter motor may actually be back-driven part of a turn as the
    engine stops...

    What does your starter actually *do* when you push the button? Does it
    just spin freely? Maybe all the cylindrical rollers in the starter
    clutch have hung up in the retracted position?
    I can't believe it either, and I *never* would have bought my FZR-1000
    if I had known about that stupid buried starter clutch. I talked a a
    guy who had problems with the starter solenoid on his FJ-1100. It would
    hang up, and the starter would keep on cranking the engine after it had
    started. He didn't know how to stop the starter from turning, so he
    gassed the engine, thinking that the starter would somehow
    automatically stop cranking the engine...

    It didn't stop cranking, it kept turning that starter chain, and the
    starter chain broke! It cost him $900 to have that starter chain
    replaced...
    is in great shape. Normally, if you had to split the cases
    rebuild on the engine while you had things apart
    out of proportion to the cost of the starter clutch parts. Damn!!

    I hear you loud and clear...
     
    krusty kritter, Feb 26, 2005
    #4
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