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  1. #61
    casey67's Avatar
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    Quote Originally Posted by Sage18 View Post
    Anyone on here have a seat for a 2000 pro 1200? Will the SLX 1200 seat fit?
    The upper body is the same as 98-2001 SL's. Yes the SLX or SLH seat will fit.

  2. #62
    Sage18's Avatar
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    Ok so now I have a fleet of older 95-2001 Polaris and Seadoo jet skis picked up for minimal investment. Here is the list: 1995 SL750, 1996 SLX780, 1996 Seadoo XP, 1999 Polaris Pro785, 1999 Seadoo GSX, 2000 Polaris Pro 1200, 2001 Polaris SLX 1200. 3 machines need work. The GSX is seized in some way havenít taken it apart yet. The Pro 1200 turns over by hand but the starter is toast. And the 785 runs but low compression (112-110-115) front to back. My plan is to tackle the 785 first. Obviously carbs and fuel lines are first for me and then address the exhaust valves, triple exhaust pipes, and cooling lines. I ran it for a few short times already and it seems to run great. My issue is that it has a lower compression than Iíd like to have so a top end is in store. A few have said to get ahold of some 750 pistons and rings. Iím thinking if I do have to redo the top end Iíd like to do it right and do it once. What pistons are best? I havenít done anything yet but planning right now. Also what is the best bang for my buck in mods. Iím not racing this thing but just having fun with it! I have spent plenty of time on the hulk reading every 785 post I see and am ready to work on this 785. Previous owner didnít know much about it but used it for the past 4-5 years. I welcome all thoughts and suggestions. Do I tear it right down to the crank? Thanks in advanced.

  3. #63

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    I don't think you need to split the cases. Check the insides of the wrist pins, these rods like to pit sometimes.

    I always run Wiseco 785 pistons, but they are forged so you HAVE to be careful warming it up and babying it before it gets warm coming out of the pissers. Wiseco makes their pistons, so even if they don't have any in stock you can always wait a few weeks for them to make them. The 750 pistons I believe are cast. If things go sour they are less likely to have a problem with the nikasil. I just put sleeves in my skis when I have something go wrong. I can do it all in my shop with my dad so I can get away with it. But you probably can't. So it's something to think about.

    I always use cometic gasket kits too.

    If you have time, the best mod you can do is smooth out the exhaust ports and match the ports to the manifolds, and smooth out the exhaust manifolds in the inside the best you can. The idea is to get air out of the engine as quickly as possible with the least resistance. They are cast, so the insides are rough with casting imperfections. Those rough spots collect carbon, oil, etc. and make air flow poorly. You don't want to remove any material or change the shape of the ports, you just want to remove casting boogers and smooth it all out the best you can.

    All of my 785s have the exhaust ports polished to the point you can see your reflection in them with a little fuel and oil on them. It's hard to get all of the mainfold insides done, but you should get the insides the best you can.

    That is free to do (it will take you some time to do a good job), but it's a good improvement.

    Before you start bolting stuff on and making drastic changes, you should get the carbs dialed in right first. These skis are finicky and very picky, you can easily lose a lot of power because the carbs aren't right. A stock pro that is properly tuned will be faster than a modded up pro that no one even bothered to go through the carbs on.

    I spent a bunch of time properly adjusting pop off pressure and tweaking my black pro, compared to the other one that I didn't touch (besides polishing ports), the black one runs far better. Seems like the carbs being spot on is the difference between my GPS saying 43mph when cruising on the pipes and 38mph.

    Just my two cents but you're far better off getting those carbs set right first. It's hard because you can't water test right now, but you should go through the whole thing and get it ready. At the very least I would clean the carbs and check all the pop off pressures. IIRC they should be 15 to 18psi, but to get it to run good you want them to be all 100% even. You can slightly bend the arm to adjust it to get it perfect. Between that and polish/port, that make my pro run way better. And I have two to compare to so I can measure it with GPS and stuff. I'm not just making stuff up.

    You should spend the winter going through everything and making sure it's solid. New fuel lines, check all the cooling lines for debris and garbage. Set it up the watcon way to dry out the waterbox a little bit (search the forum, it's easy to do). It'll give you more acceleration and make it sound better. I'd check the torque on everything too, even pull the engine and check the bottom mounts. I had those go wrong at one point too.

    Always assume the guy who had it before you didn't know what he was doing and shouldn't be a mechanic, and go through it like that.

    EDIT: I don't know what it is about Pro 785s, but they seem to attract people who aren't very good mechanics and think they can just bolt stuff on to go faster. There are some very, very good and smart pro 785 people out there, don't get me wrong. But it's usually safe to assume, unless you know the person very well or they are a regular here, that they didn't know what they were doing.

  4. #64
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    Quote Originally Posted by sdlvx View Post

    If you have time, the best mod you can do is smooth out the exhaust ports and match the ports to the manifolds, and smooth out the exhaust manifolds in the inside the best you can. The idea is to get air out of the engine as quickly as possible with the least resistance. They are cast, so the insides are rough with casting imperfections. Those rough spots collect carbon, oil, etc. and make air flow poorly. You don't want to remove any material or change the shape of the ports, you just want to remove casting boogers and smooth it all out the best you can.

    All of my 785s have the exhaust ports polished to the point you can see your reflection in them with a little fuel and oil on them. It's hard to get all of the mainfold insides done, but you should get the insides the best you can.

    That is free to do (it will take you some time to do a good job), but it's a good improvement.
    Great information. Iíll go that route. Can you explain your process you use in matching the exhaust ports? And the tools you used. Do you lightly hone the cylinders with anything I know they are harder than normal. Also I have the service manual for it from Polaris is this my best source for specs or is there a better reference for me?

  5. #65

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    For matching the ports you need a carbide tip and an air tool. And you just need to take your time and be careful. I take the cylinder and manifold off so I can get a better look. Some people like to take a trace of the exhaust port that goes to the manifold and lay it over the manifold and see what needs to be removed. Basically, you just want to remove any shelves that are formed between the exhaust port exit and the exhaust manifold entrance.

    This is for 4 strokes but a lot of the concepts of cleaning things out to get better airflow applies.
    https://www.yourmechanic.com/article...-blake-griffin

    I don't use sandpaper drums, I make my own tool out of emery paper and metal rod. I just cut a slit in the end of the rod with a cut off wheel and put the emery paper in there, then put the tool I made into an air tool with high RPM and let it spin until it makes everything look nice and smooth and pretty.

    There's probably other ways of doing it. All you want to do is make where the air flows OUT of the engine as smooth as possible. No lumps, no bumps, no divots. No roughness.

    Just don't do it to the intake side. Those should be left rough so the air doesn't flow through as evenly. The turbulence from all the imperfections coming into the engine help mix the fuel and oil. It's restrictive but you need it to mix things properly, specially if you still have oil injection.

    It's an art, just take your time and keep making it smooth and pretty. If you have some really ugly castings, I've had to bump up a jet size before. I properly polished my Polaris 600 snowmobile and had to put in some larger jets. It was pretty rough. Sometimes you get them and they aren't very bad. I have a few exhaust manifolds and there is definitely not much consistency between them. But that's what casting does.

    My favorite part about focusing on polishing and port matching is that even if you do it, everything still looks 100% stock from the outside.

  6. #66
    I'D RATHER SWEAT THAN SHIVER hyoctane23's Avatar
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    I literally spent hours and hours and hours on my super stock 785 getting all the gaskets to match all the ports without any overhang, polishing the exhaust duct and matching the exhaust flange ID and gasket to the exhaust port. I didn't do any of the port work to the intake ducts in the cylinder as that really should be left to the professionals. You can probably be real careful and remove any of the casting flaws in the intake ducts to help smooth out the flow but I think really just spend time on the gaskets matching all the ports and you'll be surprised.

    If you have plenty of time, go ahead and spend the time to do so...it for sure won't hurt as long as you don't go overboard on it and get all the dimensions out of whack.

    Here are a few pictures for an idea of what I did..
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  7. #67
    I'D RATHER SWEAT THAN SHIVER hyoctane23's Avatar
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    Quote Originally Posted by sdlvx View Post
    always assume the guy who had it before you didn't know what he was doing and shouldn't be a mechanic, and go through it like that.

    Edit: I don't know what it is about pro 785s, but they seem to attract people who aren't very good mechanics and think they can just bolt stuff on to go faster. There are some very, very good and smart pro 785 people out there, don't get me wrong. But it's usually safe to assume, unless you know the person very well or they are a regular here, that they didn't know what they were doing.
    so very true!!!!!!


  8. #68
    Sage18's Avatar
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    Quote Originally Posted by sdlvx View Post
    For matching the ports you need a carbide tip and an air tool. And you just need to take your time and be careful. I take the cylinder and manifold off so I can get a better look. Some people like to take a trace of the exhaust port that goes to the manifold and lay it over the manifold and see what needs to be removed. Basically, you just want to remove any shelves that are formed between the exhaust port exit and the exhaust manifold entrance.
    .
    Great I’ll be doing this shortly and will post pics of the project. Sounds like a good plan. It’s my first 785 and I’d like dial it in this summer. What is my best source for 750 pistons? A few have recommended these over the Wiseco 785 pistons. Or if those are better?

  9. #69
    Sage18's Avatar
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    Quote Originally Posted by hyoctane23 View Post
    I literally spent hours and hours and hours on my super stock 785 getting all the gaskets to match all the ports without any overhang, polishing the exhaust duct and matching the exhaust flange ID and gasket to the exhaust port. I didn't do any of the port work to the intake ducts in the cylinder as that really should be left to the professionals. You can probably be real careful and remove any of the casting flaws in the intake ducts to help smooth out the flow but I think really just spend time on the gaskets matching all the ports and you'll be surprised.

    If you have plenty of time, go ahead and spend the time to do so...it for sure won't hurt as long as you don't go overboard on it and get all the dimensions out of whack.

    Here are a few pictures for an idea of what I did..
    Looks great. That took a long time I’m sure. That is the route I will take when I pull the motor out.

  10. #70

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    Another place of low hanging fruit to improve is the pump. The space between the impeller and the wear ring should be measured (it's in the service manual) and fixed. You can also match the parts of the pump if they are off or there's any big inconsistencies.

    I put a new wear ring and an impeller Impros went through on my superjet and it made a huge difference.

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