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  1. #1

    Rookie with 787 rebuild

    I bought a 1996 xp800 as part of a project I'm working on. The engine had water in the crank and a rebuild began.

    I've torn the engine down and now it is time to put it back together. Couple questions for the experts here.

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Name:	Seadoo 787 - Crankcase.jpg 
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    Crankcase halves apart

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Name:	Seadoo 787 - Cylinder measurement.jpg 
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    Cylinder measurements. All the measurements were within a tenth. Will 1mm over pistons work?

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    Does this alignment look correct for the Crank and Counterbalance?

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Name:	Seadoo 787 - Cylinder Hone.jpg 
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    Ran a basic flex hone through it, but still have some surface marking in the cylinder. The Mag cylinder is worse than the pto. Is this acceptable? If not, any suggestions for cleaning it up without taking off too much more?

    Thanks in advance for any help. This site is great.
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Name:	Seadoo 787 - New Crankshaft.jpg 
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  2. #2
    Should have gone with oversized pistons and have it bore honed by a profesional.

  3. #3
    I'm curious to see the answers. I'm received two 05 FX HOs that got water in them so I'm ready to pull the engine in one and start breaking it down. Good luck with your build.

  4. #4

    Join Date
    Oct 2011
    Location
    Littleton, CO
    Posts
    6
    Klein - Don't know if you are still looking for help.
    You need a manual if you don't have one. You can get a free download online at a few places, like
    http://www.sea-doo.net/SHOPMANUALS/P...1996/SMR_A.PDF

    Your crank to counterbalance looks off by one tooth to me.
    I think the cylinders are stock at 82mm, so 82.5mm won't require a 1mm over piston. Don't know what size WSM pistons you bought.
    You aren't really measuring the cylinders at the right place. If you are doing this yourself, look in the manual (or online) for where to measure.
    Or take the cylinders and pistons to a machine shop familiar with Seadoos.
    I believe the std piston is 81.89mm or 81.91mm. Since you just honed and didn't bore, you may be able to stick with the std piston, since the cylinder wall doesn't look to bad.
    Are you replacing pistons because they were damaged?
    If the case had water in it, I sure don't see any damage. If it just got water, did you try and clear it the normal ways first before tearing down the motor?
    If the water stayed in the case for a period, then you need to look closely at the bearings for pitting.
    If you need new bearings or seals, you'll need professional help to put the crank back together correctly aligned. However, if you are really into DIY and have access to a jig or lathe, there are online help sources for how to re-align the crank, which is somewhat of an art.

  5. #5
    elmatta's Avatar
    Join Date
    Sep 2011
    Location
    CT
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    311
    +1
    8
    I don't wanna hijack his thread but it may give him an answer he wouldn't mind hearing; how long do you think a crank would last if one side of the bearings had light pitting from removed rust? Is all pitting bad pitting?

    Also, can crank rebuilders just clean and put one side of bearings in? I literally see one ball-bearing maybe two slightly darkened from rust that I cleaned off. It spins freely though

  6. #6
    Thanks for the help. It has been a while since I checked this site. The engine had the water in it for an unknown amount of time. I ended up replacing the crank, pistons, rings, all seals, gaskets, etc...

    I'm using it for an aluminum boat project and just got everything into the boat this weekend. The engine starts and idles easily, but bogs and dies when you apply the throttle. I haven't had a chance to get back into it this week, but I'm hoping it is something easy with the carbs.

    I cleaned them when I had the engine apart and they looked pretty good. Pop off tested well. The interior filters on both carbs were pretty clogged, but they cleaned up well. I replaced the fuel line between the carbs as well. I'm running it off a temporary fuel system just to see how it ran. I just have a piece of fuel line on the supply and return side stuck into a 1 gallon gas can.

    Not sure where to start diagnosing the fueling issue. If anybody has a suggestion for a rookie I'm all ears.

  7. #7
    Quote Originally Posted by Ride_Klein View Post
    Thanks for the help. It has been a while since I checked this site. The engine had the water in it for an unknown amount of time. I ended up replacing the crank, pistons, rings, all seals, gaskets, etc...

    I'm using it for an aluminum boat project and just got everything into the boat this weekend. The engine starts and idles easily, but bogs and dies when you apply the throttle. I haven't had a chance to get back into it this week, but I'm hoping it is something easy with the carbs.

    I cleaned them when I had the engine apart and they looked pretty good. Pop off tested well. The interior filters on both carbs were pretty clogged, but they cleaned up well. I replaced the fuel line between the carbs as well. I'm running it off a temporary fuel system just to see how it ran. I just have a piece of fuel line on the supply and return side stuck into a 1 gallon gas can.

    Not sure where to start diagnosing the fueling issue. If anybody has a suggestion for a rookie I'm all ears.
    Check accelerator pump and ball injectors. They most probably are cloged.! you should see them squirt fuel when the throtlle is pressed.

  8. #8
    Thanks Radja. I rebuilt the carbs when I did the tear down on the motor. Not sure what the issue was, but last night when I went to mess with it the motor started and revved just fine. I have a couple small items to clean up so I can drop it in the water and give it a true test.

    Thanks again for the help offered.

  9. #9
    What are you putting the motor in?

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