Triumph trophy 900 starter problem help!

Discussion in 'Motorbike Technical Discussion' started by catherinebissett, Jan 13, 2007.

  1. The starter is turning but wont engage, can anyone help with an answer?
    Would it be possible to do it myself ith the parts and a manual (with
    some laymans knowledge from 30 years biking)
    catherinebissett, Jan 13, 2007
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  2. Starter clutch is FUBAR'd. Well-known Triumph problem, especially on the
    early 900s.

    The bad news is that it's an engine-out job to fix, and a dealer will
    charge you £800 for the job. If you're handy with spanners, then yes,
    it's do-able, but an utter arse-ache of a job. I think you need one or
    two odd-sized spanners for the engine mounting bolts.

    Sorry to be the bearer of bad tidings.
    The Older Gentleman, Jan 13, 2007
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  3. catherinebissett

    Gene Cash Guest

    Wow. How can that be? All the starter clutches I've seen live behind the
    alternator cover on the crankshaft... how did they **** things up THAT
    bad? How does it come apart?

    Gene Cash, Jan 13, 2007
  4. The parts diagrams identify the starter clutch as a "Spragg clutch",
    which makes me wonder if there are really several ratcheting sprags in
    the clutch, instead of cylindrical roller on ramps, like the typical
    Japanese Frankenstein clutch.
    Potage St. Germaine, Jan 13, 2007
  5. They based a lot of the design of the early Triumph engines on Kawasaki
    lumps, as they were the toughest of the era (some people even thought
    Kawasaki built the engines for Triumph).

    On the air-cooled Kawasaki Z650/750 series, it's the same problem. In
    theory an engine-out job, although the job can be done by removing the
    entire clutch assembly and the sump.

    On Triumphs, though, I don't think there's this work-around. In fact,
    I'm pretty sure. Just google for 'Triumph starter clutch' (esp. on
    Google Groups) and you'll see it's a well-known issue.

    The problem generally happens when the battery gets low (and Triumphs
    have small batteries). The starter struggles to spin the engine fast
    enough, the engine kicks back, and goodbye clutch.

    I've never had to do the repair, so I'm not entirely sure of the
    sequence of disassembly/reassembly, but yes, it's engine-out.
    The Older Gentleman, Jan 13, 2007
  6. It isn't just Triumphs and Kawasakis that have this @#$%^& starter
    clutch that's buried inside the engine.

    My FZR-1000's starter clutch is the very last part you get to after
    splitting the cases.
    The alternator and starter are driven by a @#$%^& *chain* off the

    Yamaha FJ's and Secas used the same @#$%^& jackshaft arrangement.

    I never would have bought a Yamaha if I'd known about that nightmarish
    arrangement. One FJ rider I talked to said it cost him $900 to have the
    starter/alternator drive chain replaced after it snapped.

    Triumph at least used a *gear* to drive the alternator shaft.

    The starter idler gear sits motionless on the alternator shaft until
    the starter turns it. Then the "Spragg clutch" grabs the alternator
    shaft and spins the crankshaft through the alternator drive gear.

    You can see a diagram of the FUBAR design on under
    ALTERNATOR STARTER DRIVE. Click on OEM Parts > Triumph > Trophy > then
    the early or late model serial numbers.

    All of this screwed up design came about when the manufacturers wanted
    to install an automotive type excited field alternator on a motorcycle
    engine. Problem with automotve style excited field alternators is the
    large diameter.

    Where do you put the @#$%^& thing? Answer: Underneath the carburetors.

    Then you design a @#$%^& jackshaft to drive it and you have to get the
    starter to drive that shaft, unless the alternative dawns on you: Leave
    the @#$%^& starter clutch in the original position, as Suzuki did on
    their GSXR's or move the starter clutch to the OTHER SIDE of the engine
    as Yamaha did with their YZF-R6 models.

    Yamaha could do this because the ignition trigger coil senses passage
    of the crankshaft counterweight, so the right hand end of the
    crankshaft didn't have to carry the ignition rotor.
    Potage St. Germaine, Jan 13, 2007
  7. True "early Triumph engines" didn't have electric start.

    '54 Tiger Cub
    '65 TR6SC
    '67 TR6R
    '69 Trophy 250
    '70 TR6R
    Project Magnet #1, Jan 13, 2007
  8. Smartarse ;-))
    The Older Gentleman, Jan 13, 2007
  9. Your point?

    Project Magnet #1, Jan 13, 2007
  10. Does Sir know what an "emoticon" is?

    Did Sir note the emoticon following the word 'Smartarse'?

    Has Sir now deduced the sentiment behind the posting?
    The Older Gentleman, Jan 13, 2007
  11. Yes

    I guess I should have used one also.

    Project Magnet #1, Jan 14, 2007
  12. catherinebissett

    John Johnson Guest

    Don't take it too hard. When one spends as much time arguing against
    B-12 as TOG does, it's easy to start taking everything seriously.



    'indiana' is a 'nolnn' and 'hoosier' is a 'solkk'. Indiana doesn't solkk.
    John Johnson, Jan 14, 2007
  13. I've read enough from him over the years that I know how he can be. I'm
    not taking anything hard at all, he was correct, I was being a smart ass.

    Project Magnet #1, Jan 14, 2007
  14. Fifteen-all.
    The Older Gentleman, Jan 14, 2007
  15. To answer my own question,
    shows a
    Spragg clutch, which is like a non-tapered roller bearing. But the
    "rollers" are eccentrically shaped, they cannot roll, they can only
    wedge against the inner and outer races.

    And that leads me to wonder whether a Spragg clutch is ever quite 100%
    disengaged, or do the eccentric bits always rub on both races just a
    tiny bit, wearing themselves out...
    Potage St. Germaine, Jan 14, 2007
  16. Aaarrgh. It's got to me at last.

    Sprag clutch. *Sprag*.
    The Older Gentleman, Jan 14, 2007
  17. Take it up with Hinkley. "Spragg Clutch" is the terminology used on the
    official Trophy parts diagram.

    "Sprag" is a term possibly derived from Danish. A "sprag" was a prop to
    stop a wheel from turning. Sprags are also used to stop a vehicle from
    rolling backwards

    A sprag is a starter freewheel clutch used in the electric starters of
    modern motorcycle engines to replace the "bendix" common to auto
    starters. It resembles a roller bearing with rollers shaped like a
    figure eight and cocked with a spring as it turns one way they stand up
    and bind because of oil friction and slip in the other when the motor
    is running.

    Another diagram with figure 8 shaped sprags and an explanation of sprag
    clutch operation
    Sprag clutch races wear out during ordinary operation at high RPM.

    Aprilia (Rotax), Laverda, Ducati, and Triumph use sprag clutchs that
    wear out.

    The typical Japanese Frankenstein clutch as used by Suzuki and Yamaha
    cannot wear during overrunning operation as the cylindrical rollers do
    not contact the idler gear.

    "DEXRON®-VI Sprag Clutch Overrunning Wear Test (SCOWT)
    The SCOWT is an OEM designed test to evaluate a fluid's anti-wear
    properties using a transmission one-way roller clutch. The clutch is
    mounted between two opposing rotation motors, which create a
    differential rotating speed of 16,800 rpm, and run for one hour. Weight
    loss of the inner race of sprag clutch is used to determine amount of
    Potage St. Germaine, Jan 15, 2007
  18. Silly sods. Sprag is the right spelling.

    And we *know* they wear out......
    The Older Gentleman, Jan 15, 2007
  19. And you don't bother to warn potential purchasers that a critical part
    that will wear out and leave the buyer up the proverbial creek without
    a paddle is buried in the engine?
    Potage St. Germaine, Jan 15, 2007

  20. Get real!

    Anyway, as far as Triumph is concerned, they beefed up the sprag
    clutches some years ago and it isn't really a problem now.

    Triumph were very good with the warranty claims, covering a lot of the
    affected bikes way after the warranty had expired.

    You can only do so much with factory testing. Whatever you do to test a
    product, especially a vehicle, there's always something that you won't
    have thought of, and the end user will always find a new way of
    breaking it.

    The old Peugeot 309 - small family hatch, sold in Europe a couple of
    decades ago. I had one - was a classic. There was a rash of the rear
    tailgate screens popping out and shattering on the ground. Peugeot was
    completely foxed, because during testing they'd opened and closed the
    rear hatch thousands and thousands of times, and never had a problem.

    When they examined the reported cases, they found that the affected
    drivers were mostly female, and the damage mostly happened at
    supermarkets and other shops.

    What the drivers were doing was loading their shopping into the back of
    the car, and then insead of cosing the hatch from the six o'clock
    position behind the car, were shutting it with one hand, from the side,
    as they walked back to the driver's seat. This was especially prevalent
    when they were either holding a baby on the hip, or the hand of a small

    The action of closing the rear hatch from the side was enough to twist
    it ever so slightly, and the shock of it closing was then enough to pop
    the screen. So Peugeot beefed up the stiffness of the hatch and the
    problem was solved.

    Trouble these days is that consumers think that their purchases should
    last for ever and ever and ever and wail when they don't.
    chateau.murray, Jan 15, 2007
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