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  1. #1

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    Purchased engine but have a question, maybe more

    I lucked out today and found a complete engine for my 1994 SLT 750 project for $200. Pretty clean, and by complete, I mean everything but the water box. Also came with a whole wiring harness, e-box, CDI, and coils (I have another setup I bought off here that I may be selling now). Engine spins free, made compression, and pistons looked good; a little wet and black but not damaged.

    Anyway, this is out of a 95 or 96 780. It has the two black bedplates. I was wondering if those will work with my SLT 750 hull or if I need to find the correct big blue one.

    That's all I can think of for now, but I'm sure I'll have more questions as time goes by. Once the engine arrives, I'll be starting a build thread.


  2. #2
    BlueFishCrisis's Avatar
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    You will need the big blue bed plate for the 94 SLT motor mount locations. The split plates were for installing a 780 in a hull with mounts for a 700. The motor mount spacings are different. I have spares, but the shipping is probably outrageous.....

  3. #3
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    I don't think shipping would be too bad. Wrap the plate in cardboard and send it. It doesn't need much protection from damage as it's a chunk of aluminum. I'd guess around $25 to ship by USPS.

  4. #4

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    Thanks for the information, I'll double check when I go down to pick up the motor this weekend to see if they have one laying around. Plus there are a bunch on ebay with free shipping that are reasonably priced. One thing I do need are the specific motor mounts and attaching hardware for a 94 SLT; all the ones they had in their yard were the angled ones out of other hulls.

  5. #5

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    OK I'm back with a quick question. When I go back Saturday to get the motor, once I get home I plan on taking the manifolds off to inspect parts and whatnot. I really want to do a compression check and the crank index check. I work on cars for a living at the moment, and I know that we have occasionally bench tested a starter using a jump pack with the negative cable clipped to the starter body and the positive cable hooked to the starter post. I'd like to use that same method to crank the engine outside of the ski. Is there anything wrong with using a jump back to do that on these engines?

  6. #6
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by kevinz View Post
    OK I'm back with a quick question. When I go back Saturday to get the motor, once I get home I plan on taking the manifolds off to inspect parts and whatnot. I really want to do a compression check and the crank index check. I work on cars for a living at the moment, and I know that we have occasionally bench tested a starter using a jump pack with the negative cable clipped to the starter body and the positive cable hooked to the starter post. I'd like to use that same method to crank the engine outside of the ski. Is there anything wrong with using a jump back to do that on these engines?
    That would work, just make sure the engine cannot shift around while it is cranking.

  7. #7

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    Sounds good, thanks. I have another question. Since this is a 780 engine going into a 750, I've heard I need the 780 throttle and choke cables. I may try and get those from the junkyard Saturday if so. Or, I'll have some 750 carbs and air arrestor for sale after I get the engine, so maybe I can trade those for the cables and the blue engine bed plate.

  8. #8
    BlueFishCrisis's Avatar
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    You can use the 750 cables, but you will need a 750 intake manifold. The only essential difference between the two carb connections is they are oriented 180 degrees opposite each other, resulting in longer cables as the connections are at the PTO end of a 780 vs the MAG end of a 750.

  9. #9

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    Awesome, I have a 750 intake manifold sitting here. So I guess I'm set there. I'll be posting a set of 750 carbs, air intake, exhaust manifold, and possibly some electrical box stuff soon.

  10. #10

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    Just wanted to throw in an update...I went and got the engine today. got it home and started looking it over and running some tests. this thing is extremely clean both inside and out. It cranks great and has 145 psi of compression in two cylinders and 140 in the other, so I'd say that should work. I also did the "redneck" crankshaft index test and assuming I did it right, that area is OK too. There was still a healthy coating of oil internally, and when I pulled off the flywheel cover, the flywheel and stator look brand new. I don't think this engine ever had water get where it shouldn't be. The electrical box is complete and looks great; I may use it and sell my other or keep it for parts. It even came with the bilge pump and it powers on.

    As a bonus, the motor mounts are in the way from board member fixer (who is great to deal with btw!) and I scored a bedplate for $18 shipped off ebay. So not much longer and I can sit it in the hull. I only need a water box, mounting bracket, bungee, and some of the molded rubber hoses now; I'll have some spare 750 parts up for sale soon along with a set of 780 bedplates and will consider trades for those parts I need.

    A quick question about the fuel pump; I assumed this engine came with it mounted on the carb rail like the 750 carbs I have, but it did not. The cut remains of the three inlet hoses to the carbs is still there so I know it had the triple outlet pump originally. I heard somewhere that it is mounted to the hull on the 780s. For those that have put one of these engines in a SLT 750, where does the pump mount to? The engine has the black carbs if that makes a difference.

    Thanks to everyone for the help so far; this board is amazing and I look forward to getting my ski going!

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