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  1. #1
    Sage18's Avatar
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    1999 Polaris Pro 785 purchase

    I have an opportunity to pick one of these up and wondering thoughts on them. I found one for 1500 in my area with the top end rebuilt 5 years ago by a performance shop. Do these machines need a bunch of maintenance? Iíve worked on many jet skis just never on a pro 785. Tips on anything? Good buy at 1500? Compression test was 130+ in each hole. It appears to be stock nothing done to it. Heís going to let me take it out before I decide to take it. Should it hit 7800 rpm at WOT?

    I should do the carbs over this winter anyways. Also anyone still have parts for these things on here? I see some on eBay. How about a shop manual? Can I buy one on here from anyone? Any thoughts are appreciated


  2. #2
    Sage18's Avatar
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    Also I have a 2001 SLX 1200 am I going to see much difference in performance in the 785 compared to the 1200?

  3. #3
    Moderator HiPeRcO's Avatar
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    I hear the 785s are VERY temperamental. The 1200 SLX is likely going to require much less fiddling and as a result much more ride time.

  4. #4
    Click avatar for tech links/info K447's Avatar
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    Quote Originally Posted by Sage18 View Post
    Also I have a 2001 SLX 1200 am I going to see much difference in performance in the 785 compared to the 1200?
    Different hulls, different engines, different performance. Pro 785 hull can hang onto the water and turn with authority. The SLX hull is, IIRC, flatter bottom and different in handling.

    The 785 engine can really scream, but it MUST be all running 100% perfect. It has triple exhaust pipes and electronically controlled exhaust valves. Lots of parts and the exhaust pipes can be difficult to work around. Often several of the pipes have to be removed just to get at other things around the engine, then put back in.

    The 1200 by comparision is simple to work on and not nearly so critical in tuning.

  5. #5
    Sage18's Avatar
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    I have a few skis so I don’t mind the leaving it behind and tuning it to get it right. The electronic exhaust valves I’ve read about but haven’t worked on them before. I’ve repaired and tuned the sea-doo RAVE valves before without any issues. Do they fail frequently? What about WOT, I think I should see 7800? Correct? My SLX hit slightly over 6700 WOT.

  6. #6
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Similar top speeds, but totally different animals. 785 around 63 MPH stock and SLX 1200 about the same, maybe slightly more on flat water.

    Pro 785 when running correctly will accelerate much better than the SLX.

    Pro 785 will carve a hard turn and throw you off if not ready for it. SLX is a flatter bottom hull and may slide out a little easier. I noticed the SLX has a tendency to porpoise under certain conditions.

    The SLX is simpler in design as because of that it's easier and normally more reliable. The Pro is more complex with more moving parts, but when running correctly, is an awesome ski. Tough to wipe the smile off your face when those pipes and valves come together and make her sing. It's not a maintenance nightmare, just more complex when trying to diagnose a problem.

    Some parts are available, some are more difficult to find. Pistons no problem. Cylinders re-plated no problem. Crank shaft parts are so-so. Gaskets no problem. Reeds no problem. Factory heads, no problem. Exhaust valves are getting harder to come by. Exhaust valve actuator and cables are getting tough to find. Factory pipes are no problem. (they are aluminum and can be welded if need be) Impeller and pump parts are all easy to come by.

    So depending on what you need, might be tough, or might be easy.

    Yes, a stock 785 should turn 7800 RPM with no problem. And get there in a hurry.

    $1500 for a good running pro is a great deal. Money well spent for the fun you will get if she's running right.

  7. #7

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    I like the Pro 785 so much I have two of them. One to keep stock and one to play around with modding. I got my first pro when I was about 14 years old, I'm 33 now. I've been wrenching on them ever since.

    Pro 785 can be a nightmare of problems, or pretty reliable. It all depends who had it before you and who took care of it. The first Pro I had, came from a dealer where the owner's kids were absolutely idiots and shouldn't be allowed near wrenches. I was chasing problems with that ski for a good ten years. Everything from constant seizing, engine not being properly mounted to the plate, etc. They lied pretty good about what happened. Split the cases a year or so ago, nice gouges in the side of the rear reed ports, someone blew it up real good at one point.

    Eventually, I fixed that one from those horrible people. I usually get about three or so years out of it (riding it once a week between may and september) before it needs some attention, usually a cylinder gets seized. And I ride hard, usually after an hour of riding I struggle to open up my hands all the way.

    The other one I recently got, from another guy who had zero idea what he was doing. Pipes clogged with sand, timing completely wrong, carbs completely wrong, etc. I have a poorly done build thread posted here. He said the crank was wrong but that was the only thing right. I could go on and on about how this guy ruined this ski.

    It's fixed now, runs amazing.

    These things CAN be a handful if the previous owner isn't very good. There is a lot of complex stuff on these pros. The ignition sparks in each individual cylinder while all other polaris triples do all at the same time, electronic exhaust valves, triple pipes. Pro 785 is basically just a Fuji 750 engine that's been stroked and made into a race boat from the factory. If you're a decent mechanic and you are thorough, you can turn a troublesome pro into a pretty reliable machine.

    That said, I've been having really good luck with my pros lately, they want to be babied a little more than regular skis. Let them warm up properly, don't run them in water under 60 degrees, don't run around with it wide open, try and keep the pump hooked up or let off the gas when jumping. And when you start to feel like something may be wrong, STOP RIDING AND FIX IT. I noticed lots of other skis I have (650 Superjet, 750 SXI) or had (SL 750) can have little things not feel 100% right and still run forever. Pro 785, you notice one little thing wrong and it's going to have problems.

    Power band on these things is ridiculous, 4000 rpm is 6mph and 5000rpm is 40mph. They are a lot of fun, they get to 45mph extremely fast and they corner very hard. Honestly they are the only couches I ride that I enjoy. Just don't get put off by the 135hp, the power to weight ratio is more like a 250hp 4 stroke ski, except there's far less drag in the water because the hull is lighter than a 4 stroke stand up (lol).

    Parts aren't that bad. You can have the stator rebuilt. Wiseco and some other brands still make pistons. I personally use Wiseco. Wiseco just makes their pistons so they'll always be available, they just have to run them through the machine. Remember how I said this was basically a race-ready 750 fuji? You can use 750 fuji pistons in your pro (I never personally have). Same thing with sleeves. Some people like to reline them. I can bore and sleeve them myself, so I just have to pay for parts. LA Sleeve makes all their sleeves, if they don't have it in stock they will make it when you order. Or you can always fix your old one and have it relined. I like the idea of eventually sleeving all my cylinders and boring the thing out to true 800cc.

    Crankworks can get you connecting rods. The bearings for the crankshaft are hard to find because they have a groove cut into them. But the diameters are standard. When Crankworks redid my original pro's crankshaft (I noticed pitting on PTO connecting rod wrist pin hole) I just had them replace all the bearings and connecting rods. SBT still has connecting rods, and while SBT is usually super bad trash their rods are decent.

    Cometic makes their gasket kits on demand like Wiseco's pistons. If they don't have them in stock you can just call them and they'll make them.

    Electronic exhaust valves aren't too bad. There's a wire that comes up from the CDI that sends a signal to the valve motor. There's a potentiometer in there that usually wears out. You can get them from the internet (it's posted somewhere on this forum) for like $15 and fix it. There's also an electric motor in there with a threaded shaft. The motor spins around and pulls the cables in. Sometimes that motor goes bad. You can buy new brushes or send the motor off, there are places that will repair electric motors.

    Only thing that really scares me is the CDI. Those are impossible to find and if they go bad you are probably in some serious trouble.

    Carbs are standard Mikuni SBN, nothing special. Parts everywhere. Pump is very similar to other Polaris models.

    Some parts are shared between other models. The driveshaft is used in the SL 700, SL 780, etc.

    One thing to note is these things love gas. I put about 8 gallons in, it only takes premium, and get a little over an hour out of it. But honestly that's all my body can take and I am in decent shape.

    If you find a pro for sale, it's probably broken and all messed up. Which means finding a parts boat is pretty easy. There's also a good community of pro people around. People realize that a 470 pound, 135hp couch is never going to ever be made again and we all like to help each other out. This place is really great for it. There may be faster skis but you're not going to find something you can throw around, jump on, etc like it.

    $1500 for a pro that's running is an awesome deal, specially if it has a trailer. I paid $800 for my non-running one, $500 to ship it from Florida to Wisconsin. Plus plane tickets back and forth. I spent around $1500 for a non-running pro after all was said and done.

    I think after you ride it for 15 minutes you will throw $1500 at the guy and walk away with it. There's never going to be another sit down jet ski made with this weight, acceleration, and handling in a combo. Sometimes I end up with big bruises on the inside of my legs from trying to stay on. Sometimes I go over the handlebars. Sometimes I get flung off the back. These things are freakin awesome and there's never going to be another ski made like this again. I know people in four strokes look at me and get jealous when they see me jumping and cutting back and forth. Always funny to watch them hit a wave I got two feet of air off of and just plow through it.

  8. #8
    Click avatar for tech links/info K447's Avatar
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    Quote Originally Posted by sdlvx View Post
    ... don't get put off by the 135hp, the power to weight ratio is more like a 250hp 4 stroke ski, except there's far less drag in the water ...

    ... a 470 pound, 135hp couch is never going to ever be made again ...
    The Yamaha EXR gets close, 540 pounds dry weight. Circa 110hp with stock tune.

    Seadoo Spark has entirely different hull design, tuned engine puts out approx 110hp, only 410 pounds.

  9. #9

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    Quote Originally Posted by K447 View Post
    The Yamaha EXR gets close, 540 pounds dry weight. Circa 110hp with stock tune.

    Seadoo Spark has entirely different hull design, tuned engine puts out approx 110hp, only 410 pounds.
    True but EXR stock can barely struggle to make 50mph, no way it has enough balls to start jumping. 110hp Spark might be in pretty good shape, though you're still talking 20% more power on the pro. Not to mention those HP ratings are always peak HP and not the whole story of the power band. I like the pro because it has a feeling of having too much power in such a small hull.

    I haven't been on too many 4 stroke skis, but the ones I have been on don't come close to hitting hard. Some with more power than a pro 785.

    I do like how EXR and Spark have been trying to make pwc that aren't giant boats and I hope we see more like that.

  10. #10
    Click avatar for tech links/info K447's Avatar
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    Quote Originally Posted by sdlvx View Post
    ... EXR stock can barely struggle to make 50mph ...
    Do not conflate the base EX model with the uprated EXR.

    EXR has less weight and more power than EX.
    Stock EXR is not Pro 785 fast, but it is quicker than EX.

    https://www.boattest.com/review/yamaha/3834_exr

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