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  1. #1

    1993 Polaris SL750 Questions!!

    Hello everyone!!! It has been a while but I have a friend who has an 1993 Polaris SL750 that he let me take and fix for him and in return I can ride whenever I want. I did own a 1995 Polaris SL750 a couple of years ago but ended up blowing it up. Blew a Rod Bearing to be exact. Anyways I am familiar with these machines and know the pro and cons about the SL750. Either way this PWC has been sitting for 3 years outside in his back yard. The last time it ran it was running rough. The bad thing is he did not winterize it. Now I have already done a compression test and there was a 128 on the back cylinder, 128 on the middle cylinder and a 120 on the front cylinder. I do know these PWC have issues running lean on the front cylinder because of the fuel distubution. These are some of my ideas of what I should do. Replace all fuel lines, Fuel pump/replace with SL780 fuel pump and clean the carbs. I also do know prior to its last run he said there was some noises coming from the jet pump. When I looked in the pump I did notice the impeller was chewed up a little. What should I do other than replace the impeller? Bacically what I am asking is what would you do before you made an attemp to get it running again since it has been sitting for 3 years?


  2. #2
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by Great_Outdoors_5911 View Post
    ...1993 Polaris SL750 ...I am familiar with these machines and know the pro and cons about the SL750.
    ...been sitting for 3 years outside in his back yard. The last time it ran it was running rough. The bad thing is he did not winterize it.

    ...compression test and there was a 128 on the back cylinder, 128 on the middle cylinder and a 120 on the front cylinder. I do know these PWC have issues running lean on the front cylinder because of the fuel distribution.

    These are some of my ideas of what I should do. Replace all fuel lines, Fuel pump/replace with SL780 fuel pump and clean the carbs.

    I also do know prior to its last run he said there was some noises coming from the jet pump. When I looked in the pump I did notice the impeller was chewed up a little. What should I do other than replace the impeller?

    ...what would you do before you made an attempt to get it running again since it has been sitting for 3 years?
    Welcome back!

    You may find some of the info available here to be useful - Polaris Service manuals, parts manuals, etc.

    Polaris says up to 10% variation in compression between all cylinders is OK. When you checked compression, was the battery really healthy, all spark plugs out, and the throttle pinned open?

    You can peak through the spark plug holes to look for any obvious signs of piston damage. Rotate the engine so each piston is near BDC, and use a very small flash light.

    Not winterizing means the carbs need to be cleaned, as you intend to do. Triple outlet fuel pump and new fuel lines+filters is a good idea. I suggest you also drain the fuel tank, and put in fresh fuel.

    Check the oil tank for any signs of water in the bottom, just in case.

    There is a possibility that rust may have begun in the crank case roller bearings, since the engine was not fogged. Hopefully the 2-stroke oil from the last run was enough to protect the crank, but you won't really know unless you tear the engine down.

    Since the jet pump is suspect, I would suggest you remove the pump and drive shaft. While the jet pump is off, turn the engine over by hand with the spark plugs out, and feel for any internal bearing roughness as it rotates.

    Check the drive splines on both ends of the drive shaft, and inside the impeller and engine coupler.

    The 1992-1993 Polaris models used a non-modular 146mm jet pump. From 1994 onwards Polaris used a modular 148mm jet pump, which is a better design. If the current 146mm impeller, stator or wear ring needs replacement, then you should consider installing the 148mm pump type.

    Spin the impeller by hand, and listen for any signs of grittiness or play in the impeller stator bearings. It should turn very smoothly. The stator bearings and seals will need replacement if you suspect/feel that the bearings are failing.

    When the jet pump is mounted on the hull, the impeller clearance inside the jet pump wear ring should be under .020", and preferably under .010"

    The impeller should not actually touch the wear ring at any point. If the wear ring is worn, then it may need to be replaced. For your '93 SL750, the wear ring is also the pump mounting base.

    You have the option of changing to an extended version of the 148mm jet pump, which moves the impeller, stator and nozzle back another four inches, and the extension ring becomes the wear ring. This means you can leave the worn wear ring (the pump mount base) in place.

    The extended pump improves performance, but you will also need a longer drive shaft. Sometimes you can find an entire 148mm jet pump for sale for not much more than the price of an impeller.

    Dinged or bent impeller blades or chipped stator blades will reduce performance, but shouldn't cause mechanical noises.

  3. #3
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    When the carbs are off, try and get a good look at the crank for signs of rust. Sitting for so long without being winterized might be an issue.

    If you're going to replace the impeller, might as well replace the pump bearings too. That's if the stator isn't chewed up also.

    If she sat, I'd do the carb rebuild, new fuel lines, new in line filters, clean/inspect the petcock, and triple outlet fuel pump. IF the crank isn't rusted up.

  4. #4
    Thanks for all the info K447 and xlint89. My plan tonight is to pull off the jet pump and carbs to inspect the crank. If everything is good to go then I am going to upgrade the Jet pump to a 148mm pumped from a 94 or newer ski. I remember when I was taking my old Polaris carbs off it was difficult to get them off . Is there an easy way of taking the carbs off or is it just a pain either way? I let you guys know how everything is.

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    Lake Mead Bum & BTLS Mark starflight's Avatar
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    Quote Originally Posted by Great_Outdoors_5911 View Post
    I remember when I was taking my old Polaris carbs off it was difficult to get them off . Is there an easy way of taking the carbs off or is it just a pain either way? I let you guys know how everything is.
    It's a bit of a pain, but the more ya do it the easier it gets. I had to pull my carbs about a dozen times last season, and can pull them in about 5 minutes or so now.
    Take a look here, and here for more info.

  6. #6
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Sounds like a plan.

    Remember that you'll need to re-align the jet pump to the engine after the jet pump swap out.

    If you've removed the carbs once before, you'll be able to do it again. It is a pain regardless, but you will get faster at it like Starflight mentioned.

    12mm short wrench and skinny arms are the best things to have.

    TIPS:

    not a bad idea to place a towel under the carbs if you drop a nut, it won't slide under the engine. Keep a telescoping magnet handy for parts that do fall under there (even though they are SS, there's enough steel for a magnet to grab them)

    keep the carb stud threads as clean as possible. It will make it much easier when istalling the carbs to run the nuts on by hand than having to wrench them on all the way.

  7. #7
    Well I have some bad news. I believe there is water in the crankcase. After I removed the jet pump and was able to spin the crank it felt like everything was OK. Spinned freely. But when I got the carbs off and cut the fuel lines to the pump I then decided to spin the crank again thats when water started to squirt out the the line going to the bottom of the crankcase below the fuel pump. Am I right about there should not be brown water comming out of there? If so what would be the next approach. Is it worth rebuilding the crankcase? Like i said everything seemed to be good and felt like it turned nicely. How would water get in there? Was it becuase it was not winterized and something cracked?

  8. #8
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by Great_Outdoors_5911 View Post
    Well I have some bad news.

    I believe there is water in the crankcase. ...water started to squirt out the the line going to the bottom of the crankcase below the fuel pump.

    Am I right about there should not be brown water coming out of there?

    If so what would be the next approach. Is it worth rebuilding the crankcase?

    Like i said everything seemed to be good and felt like it turned nicely.

    How would water get in there? Was it because it was not winterized and something cracked?
    You are correct - there should be zero water coming out of the crank case pulse fitting.

    Brown water means rust - the steel roller bearings inside are toast.

    Repair means taking the crank shaft out of the engine, and having it rebuilt. Crank shaft rebuilding requires special equipment and knowledge.

    How the water got in there? Possibly a cracked crank case, as the early model year Fuji's had a water jacket around the crank case, which required a specific draining process to avoid freeze damage.

    You might as well pull the engine, and look it over carefully. You may end up shopping for another used, but running engine... Or at least not rusted and cracked.

    There is one currently available for $700

    Or part out what is still good from the entire watercraft, and use the money to shop for something in better condition.

  9. #9
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Brown water = bad

    Remove the engine and open her up. Lets get a true feel for what's salvageable and if it's worth the repair to you.

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