SBT Jetski Engines, Parts & Accessories

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  1. #1
    Joined
    Jul 2005
    Posts
    49

    Default Tech Question re SBT 657 Engine Install

    Getting ready to install my SBT 657x, the engine beat the factory manual to the door and I'm stuck with only a Clymers.

    Can someone explain the static timing procedure. I bought a dial indicator and I'm making the timing shroud that goes over the PTO to align the mark for dynamic testing. Unless other suggestions using sheet metal.

    I know that you back off the TDC mark and bring it up to .102" which gives you an advance of 19-21 degrees. According to Clymers you then mark the PTO once the aforementioned distance has been set.

    The stator has three slotted holes with about a .250" of an inch of travel. The only problem is that I don't see any reference marks on the stator housing? One would think that there would be some kind of boss there or notch on the stator ring. So do you just set it in the center for an initial setting?

    Correct me if I'm wrong does this assembly (stator) consist of three charging coils (3 phase ac) and a pick up coil at the top for generating a voltage to the trigger circuit. When the magneto cup assembly slews around to the top, the magnets attached to it generate a current in the coil which is rectified and triggers the high voltage circuit to fire and arch across the plugs. So the advance and retarding of the ignition timing is controlled by the rotation of the stator ring on the slots. So am I to assume that static timing is merely guessing where the coil should be aligned? Then you proceed with the dynamic timing to verify the setting? The you disassemble the magneto adjust it again then test, repeat and test?

    Another question is I wanted to verify the rotary valve timing on a 95 5863-GTX. According to Clymers its 142-152 degrees btdc.SBT installation guide says its 147? Which is correct?

    The clearance between the valve and valve cover is .010-.014"? (Clymers)

    The torque specification for the rotary valve cover is 17 lbs?

    Last question, when intalling the Pto do I put anti seize or locktite?

    Thanks

    Chumbi

  2. #2
    Joined
    Mar 2003
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    SBT
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    21,545

    Default Re: Tech Question re SBT 657 Engine Install

    Use hand tight for the rotary cover, about 6 ft. lbs.


    Both specs are right for the timing - it's 147 +/- 5 deg.

    Yes 10-14 thou.

    You do not need to time it with a light, just set the stator to the standard base timing by aligning the marks at 10 o'clock (see the tech article if you need a picture).
    SBT Tech Support is here to help with your problems.
    We try to answer each question quickly and accurately.
    Please do not use Private Messaging for Tech Support, use the forums.

  3. #3
    Joined
    Jul 2005
    Posts
    49

    Default Re: Tech Question re SBT 657 Engine Install

    Thank you tech support your up late =oP

    Any suggestions on the PTO flywheel thread. Anti seize or Loctite?

    Thanks

  4. #4
    Joined
    Mar 2003
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    SBT
    Posts
    21,545

    Default Re: Tech Question re SBT 657 Engine Install

    Nope
    SBT Tech Support is here to help with your problems.
    We try to answer each question quickly and accurately.
    Please do not use Private Messaging for Tech Support, use the forums.

  5. #5
    Joined
    Jul 2005
    Posts
    49

    Default Re: Tech Question re SBT 657 Engine Install

    Bill anyone? Re engine timing procedure and what to put on the threads of the PTO flywheel?

    I was also wondering how the 657 engine handles timing advance and retardation. On most conventional engines there are mechanical means such as centrifugal weights or vacuum advance. Does the DC-CDI unit do this electronically?

    Is the correct RPM to check it at 60000?

  6. #6
    Joined
    Nov 2003
    From
    Glendora, CA
    Posts
    6,846

    Default Re: Tech Question re SBT 657 Engine Install

    Yes the timing curve is set electronically. There is a mark on the stator plate, left side about the middle of the slot. No need to advance or retard the timing, just set it per the instructions given.
    I use Blue Loc-Tite on PTO threads, just to keep it tight so I can start the motor on land and shut it off without the pto backing off of the crankshaft. The pto will tighten itself as you ride the ski, so after the first ride, backing off will not be a problem.
    If you want to check the timing with a timing light, do it at a steady 6000 rpm on a COLD engine.
    Bill O'Neal <br>
    WCM
    <a href="http://www.watercraftmagic.com"

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