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  1. #1

    looking for direstion on a 2001 GTX RFI 787

    History; I acquired the ski w/engine removed due to PO replacing starter,(81 hrs on the clock). I purchased new starter,..re-installed engine got the ski going as it should,..ran great for one full season,.. beginning the second season (last yr) I noticed that due to the ski sitting over the winter, all the injection oil had migrated down to the crank case, so I assumed bad crank seals,...but as long as we started it every few days the migration was manageable. About two months into the season my brother-inlaw was riding it and said it made a terrible squeal and quit while he was riding it,...so I towed it home... I started it in the driveway and it was making terrible noises, squeals, vibrations,...I have not touched it since.. So Im at a point where do I; 1. Buy a rebuilt engine for $1k with 2 yr warrantee. or 2. Buy rebuilt crank for $300+ and do the work myself,...(Ive rebuilt many motorcycle engines and Im a decent mechanic with all the proper tools.) Your thoughts and Diagnostics are all very appreciated.


  2. #2
    This is how I run a jetski shop in the desert nmpeter's Avatar
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    the counterbalance likely took a crap.

    engine won't be rebuildable at a reasonable cost

    I'd look for a part out ski for a motor

  3. #3
    Thank you,.. I never would have guessed the counterbalance,... what causes the CB to go ??? ,... Do you think I can find a decent used motor for less than the $1000 rebuilt one that comes with 2 yrs warantee ?

  4. #4
    This is how I run a jetski shop in the desert nmpeter's Avatar
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    the cb has its own little oil supply, refer to service manual.

    for that ski the SBT with the two year warranty isn't a bad deal, but this will bring out the doubters for sure.

    it depends if your core has any internal damage from the cb fail.

    if the engine compression is solid, you might want to split the cases just to have a look see as to the fault. if it's just the CB and the gears aren't trashed, you might get away with just replacing it.


    small chance the pump threw a bearing, you'll have to pull that anyway to get the engine out, so start there.

  5. #5
    Quote Originally Posted by nmpeter View Post
    the cb has its own little oil supply, refer to service manual.

    for that ski the SBT with the two year warranty isn't a bad deal, but this will bring out the doubters for sure.

    it depends if your core has any internal damage from the cb fail.

    if the engine compression is solid, you might want to split the cases just to have a look see as to the fault. if it's just the CB and the gears aren't trashed, you might get away with just replacing it.


    small chance the pump threw a bearing, you'll have to pull that anyway to get the engine out, so start there.
    Yes,.. I made the decision to first check compression,.. and then go ahead and pop the bottom half off and see what Im dealing with,..Im noticing parts are all pretty cheap on ebay,.. so hopefully not too much damage and I can do a rebuild my self. Work begins tomorrow. Thank you for the help and inspiration.

    edit to ad; btw the pump bearing was replaced beginning of last season.
    edit to ad #2; Ive read that the 787 has open passages from the crank to the CB,..so its been said that the oil in the CB area is just for initial startup,.. but I did put oil in there,.. and with the migration of inj oil from the tank to the crankcase,.. I would think the lubrication would not have been an issue.

  6. #6
    TheBlueMartin's Avatar
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    http://www.seadoosource.com/reservoircheck.html The little I know about BS's I found here years ago.

  7. #7
    Quote Originally Posted by TheBlueMartin View Post
    http://www.seadoosource.com/reservoircheck.html The little I know about BS's I found here years ago.
    Thats exactly where I read it too... and I would have to agree that there is a discrepancy in the design,..along with many design confusions... apparently in the 947 the CB case is sealed and should be changed and maintained,..while on the 787 they claim its open to the crank and requires no maintenance,........ two schools of thinking maybe,.??

    Anyways,..interesting updated developments happened today; Upon removal of the engine I quickly noticed that the Starboard side engine mount was loose, and I could lift that side of the engine by a 1/2" ,...so my fault for never checking (re-torquing) motor mounts when I reinstalled the engine 2 yrs ago...so obviously this took out the pump bearing and was the source of all the vibrations and squealing noises from the original episode'. So,... now engine is out and on the bench... first thing I notice is the migration of the inj oil is still VERY prevalent in the crank case, I pull the spark plugs and hook up a 12v supply to spin the engine, inj oil sprayed out of every orifice ! LOL,..but motor spins great with no ill noises. ...So next I screw the compression tester on,... I got 60psi on pto cylinder,.. and 120 psi on the front cylinder..so obviously the rear cyl is hurting. So now Im faced with; ... a rebuilt crank $300 + PTO cyl $250, and a lot of my own labor,.... or a $900 rebuilt engine with 2 yr warantee,.. at this point Im leaning towards the latter.
    Tell me your thoughts

  8. #8
    Myself's Avatar
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    Whose engine are you looking at? Not sbt I hope. You'll also need to clean and test those fuel injectors and replace the fuel filters inside the tank.

  9. #9
    Quote Originally Posted by Myself View Post
    Whose engine are you looking at? Not sbt I hope. You'll also need to clean and test those fuel injectors and replace the fuel filters inside the tank.
    Im looking at this guy,.. he's a two hr drive for me so I can save some doh on shipping and his reviews are pretty decent,...2 yr warrantee
    http://www.pwcengine.com/.


    I had another thought; is there any way to change just the seal to stop the oil migration into the crank ???,... then I could get away with just doing the one cylinder and save me a ton of $$$....bc the crank and CB seem fine other than the copious amount of oil in the there. ??


    Id LOVE to convert this ski over to premix,.. but with RFI Ive read this is not an option.
    Last edited by shaw520; 05-14-2019 at 09:13 AM.

  10. #10
    Myself's Avatar
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    No, the seal is part of the crank. But here is how to stop the oil migration and ride some more.

    On the Seadoo Rotax engines with rotary valve there is a drive gear center of the crankshaft. This gear drives the rotary shaft to spin the rotary intake valve. The gears sit in an oil bath seperated from the rest of the crankcase by seals. The seals are an integral part of the crankshaft assembly and cannot be replaced without rebuilding or replacing the crank. Unfortunately sometimes these seals fail prematurely. Since the oil bath is provided via the 2 stroke oil tank and 1/2" lines, it's common when these seals fail for the 2 stroke oil to drain from the tank and start filling the crankcase causing excessive smoking, fouling plugs, and hydrolocking the engine. All is not lost!!!
    There are two, 1/2" lines to this oil bath. One is on the left side just below and center of the cylinders. This one is the return to the top of the oil tank. Other is on the right side centered just below the intake. This is the supply from the bottom of the oil tank. You will need a 1/2” barbed or pex tee, some small zip ties, a 1/2" vacuum cap, some 75w90 gear oil, some oil stop leak......the kind that swells seals, a cutting tool for the oil line, and a hose pincher ( a couple fender washers and a small pair of vise grips will also work).
    First, remove the return 1/2" oil line off the top of the oil tank. Now, loosen the oil fill cap. Blow into that return hose until you hear the bubbling in the tank. You're just blowing all the 2 stroke oil out of the bath and back into the oil tank. As someone blows on the line after the bubbling starts, someone else needs to pinch off the supply oil line from the bottom of the tank to the right side. This will keep the oil from spilling out of the line when you unhook it. Shove a folded paper towel under the supply line fitting right under the intake. Loosen the hose clamp and pull the 1/2" line off. A little oil will come out onto the paper towel.
    Next, take that supply line and loop it back to the top of the oil tank where the return WAS. Clamp it on and remove your hose picher. At this point the oil injection system is still intact and will function as it should for the fuel mix.
    Now take the loose end of the return (left) line that you were blowing into and trim it back an inch or so. The end is usually deformed a bit from the hose clamp and can cause a leak. Cutting it back gives you a fresh connection. Loop that end down under the intake and clamp it on where the supply line WAS. Now the rotary oil bath is a closed loop system independant of the 2 stroke oiling system.
    Find somewhere handy at the top of your new closed loop in front of the engine to cut it. This is where the tee will go. Go ahead and put the tee in the left side oil line and zip tie it. Now on the right side (supply) grab your gear lube and put about 2 ounces in. Then add about 2 ounces of the oil stop leak. Then back to your gear lube for the rest. Go slowly and have paper towels handy for spills. You might need a good flashlight to shine through the lines to see your oil. As the rotary bath gets full you will see the level rising on the left side.....it will take you a while. Add slowly until both lines are a couple inches from your tee.
    Finally, slip the right side onto the tee and zip tie it. Then put the 1/2" vacuum cap on top and zip tie it. Your rotary bath is now full of thick gear lube that won't seep into your cylinders. Eyeball it every now and then and add by way of the vacuum cap if you need to.
    You're ready to enjoy more ride time!!!!!!

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