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Thread: New SBT engine

  1. #1

    New SBT engine

    I just ordered a new engine from sbt for my 97 xp. My questions are, once I get new new engine how do I know what position to put the disc inside rotary valve cover, and how do I set the timing so it fires right up when I connect the plug wires. I just want this swap but been seamless so I can be back on the lake this summer. Thanks for the input.


  2. #2
    Quote Originally Posted by rotaryfc View Post
    I just ordered a new engine from sbt for my 97 xp. My questions are, once I get new new engine how do I know what position to put the disc inside rotary valve cover, and how do I set the timing so it fires right up when I connect the plug wires. I just want this swap but been seamless so I can be back on the lake this summer. Thanks for the input.
    we`re talking about a 787 here?

    simple but yet complicated: be diligent in your clean up of the original parts to be re installed.
    The hardest part is removing the PTO coupler and the Mag flywheel...
    I suggest you order the following necc tools to make the swap seamless.

    rotary valve timing degree wheel
    tool for the PTO/coupler
    flywheel puller for the mag flywheel, the type that screws into the center of the flywheel.
    These few tools will make it way more better for you...

    whatever you remove, place bolts and small parts in labeled plastic bags.
    clean all bolt threads.

    Have, Permatex copper spray on hand, Permatex spray High tack, a few tubes of 242 blue loctite, thread sealer, and grease, acetone, denatured alcohol.

    take pictures of the way things are placed/installed for reference if this is your first time.

    after you lock the crank (place a few rags in the pto cylinder until you can`t turn the crank), and remove PTO coupler.
    Use the flywheel remover tool to remove the mag flywheel, after you tighten down the threaded bolt, tap lightly on the tool and the flywheel should pop right off...

    after you thoroughly clean all mating surfaces, use copper spray on the exhaust manifold gasket, use high tack spray on the carb gaskets and the gasket between the mag housing and case.
    you`ll also need to install a new seal in the mag housing cover for the crank snout. large socket, and or seal install tool will work.
    you will need to find TDC and make the necc marks to time the rotary valve. if your valve is scored, get a new one they are cheap.

    if you don`t have a shop manual, PM me and I`ll point you in the direction to view one...

    good luck, hope these pointers help you out...

    there is much to do, I just replaced both 787`s in our boat... whew!

  3. #3
    thanks, I already know this isnt gonna be as easy as people make it seem just by pulling old motor out, there is barely any room to do to much, btw yes it is the 787, is this a weekend job or a week job?

  4. #4
    Quote Originally Posted by rotaryfc View Post
    thanks, I already know this isnt gonna be as easy as people make it seem just by pulling old motor out, there is barely any room to do to much, btw yes it is the 787, is this a weekend job or a week job?
    all depends on how you reassemble, and how easily or difficult it is to get the reusable parts off... it is imperative to have clean surfaces when installing the exhaust manifold, and other parts...

    have the carbs been gone thru? if they were never done or not rebuilt recently, then you should add that to the list.
    what was the original failure?

    I`m going to say a week, but can be done if your working around the clock in a few days...
    there are always other issues that pop up, like cleaning the mess under the original engine after it`s out, also takes time...
    all depends on your capability... good luck!

  5. #5
    original engine had a bearing go bad. I already cleaned the engine bay out . I do need to clean carb out just to make sure. Im a heavy equipment mechanic in the army so we lots of tools to pull the pto and flywheel off. when I pull the front cover off does the oil pump have to be set a certain way on the new engine as well? I really appreciate the advice pale rider

  6. #6
    Quote Originally Posted by rotaryfc View Post
    original engine had a bearing go bad. I already cleaned the engine bay out . I do need to clean carb out just to make sure. Im a heavy equipment mechanic in the army so we lots of tools to pull the pto and flywheel off. when I pull the front cover off does the oil pump have to be set a certain way on the new engine as well? I really appreciate the advice pale rider
    remove the oil pump first, disconnect the 2 lines from the rotary cover and leave oil pump in the ski with feed hose/cable attached, if you have the room to put it back on.
    cap those small oil lines so they don`t leak oil while your working on the ski...

    I have seen several types of oil pump couplers. just make sure it is aligned/clocked properly during install...

    Heavy equip mech! AWESOME!!! thank you for your service Sir!!!

    if you havent already torn the old engine down, bring the Mag piston to top dead center, now look at the position of the mag flywheel before you pull it... I know it has a key, what I mean is you`ll see the trigger, and magnet position, the reference hole in the flywheel right above and to the right, you do not need to remove the mag cup! smaller bolts... if you leave that alone and use the screw on the hub type puller, it is less parts loose to worry about, and the need to retime in the MPEM would be less likely... and you`ll be in the position to time the rotary valve with the degree wheel... use a straight edge when making your marks...

    Tip!!!: look at the pic with the white electrical tape. when you install the new seal in the mag housing, it is a bear to get over the edge on the crank without flipping the sealing lip on the seal.
    when you get your SBT 787 it will have blue tape over the woodruff key. leave that on for now. Take electrical tape and carefully wind just past that edge, about 1/16 to an 1/8th and come down on the tapered part and stop. like what`s in the pic. apply lithium white grease to new seal lip, and on the electrical tape you just put on.
    spray high tack on the new Mag housing gasket, let sit for a few minutes, stick the gasket on the mag housing and push the whole thing onto the crank snout and in place. have cleaned bolts ready to be installed. I`m pretty sure it is 242 blue loctite for those bolts.

    when you install the cover after the flywheel is on, be careful, the magnets will try and pull it around, align the dowels, push cover into place and use thread sealer here... the book calls for antisieze, but thread sealer also kinda helps lock the bolts in place and still come out when you want them to...

    if you need a peek at the shop manual I can point you in the direction... there are torque specs that should be followed, especially those smaller 6mm bolts... and the crank/flywheel nut, and PTO coupler etc etc...

    good luck!

    pick up some Mikuni rebuild kits and do the carbs... or send the carbs to OsideBill! you`ll get that warm fuzzy feeling when it all comes together and runs right...

  7. #7
    you will need some of the tools hes talking about good luck its not that hard if you dont no just ask there are lots of people here to help .

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