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Problems reaching top speed in my SL900, low end stutter as well...

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  • Problems reaching top speed in my SL900, low end stutter as well...

    Hey guys, been posting on the pwctoday forums and thought maybe I could get some additional help here :)

    Just purchased this ski a few days ago, and not really knowing much about them I kinda hopped in and purchased it after a quick ride test. I know, maybe dumb on my part, but I now own it and I think I got a decent deal on it. So, gotta deal...

    Couldn't get the ski past 44mph or 5600 rpm with one person and could barely get out of its own way with two people on it. It wouldn't really "jump" out of the hole either, would kinda stutter its way up until it planed out. Would stutter very hard and took forever to plane out. Aside from that, the ride was very smooth and we did have some good fun riding it that day. Took it home and found one of the NGK tips on the middle cylinder had come completely loose and was just kinda dangling on. Replaced all 3 plugs with the gap set at the recommended .025 and went on my merry way.

    The next ride test was only with two people on it b/c there was nowhere to switch off. Bottom end seemed alot better, the ski would almost hop out after not too much time on the throttle. The "long time" waiting went away, not perfect, but alot better. On some perfectly flat water it also hit 46mph with two of us on it. Still, no revving past 5700 rpm.

    So, a little concerned about cavitating and whatnot, I snapped a good shot of my impeller and noticed some wear marks that I'm not sure would be causing this problem. At idle and light rev with the flush kit out of the water you can hear some strange metal on metal sound and vibration that I just don't like. Here's a pic of it below.

    If anyone has had something very similar to this problem please let me know. I've gotten alot of suggestions of things to look at and I'm a little overwhelmed by it all. Thanks!


  • #2
    Re: Problems reaching top speed in my SL900, low end stutter as well...

    The metalic sound you are hearing out of the water is normal. I have owned 4 jetskis (2 bought brand new) and they all do it.

    The performance issue concerning not reaching peak RPM, could be several. First thing I would do is put new spark plugs in there. Then do a plug check and see how the motor is running. If I had to guess, I would say you need to have the carbs cleaned and rebuilt.

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    • #3
      Re: Problems reaching top speed in my SL900, low end stutter as well...

      I don't know if it relates to your overall problem on the stuttering, but you need a new stator vane NOW! That one is toasted. Get the SS one and you won't see that happen again most likely.

      Good luck on the fix up.

      Comment


      • #4
        Re: Problems reaching top speed in my SL900, low end stutter as well...

        Looks like I burnt a hole in the #1 (front) piston somehow.

        Took it out for a ride today and it just died on me at WOT, started it up again and I couldn't get it past 3500 rpm and 6mph.

        Got it home and pulled the plug, looked inside through the plug hole and noticed a nice hole in the piston.

        Looks like I'm either calling SBT or just selling the **** thing and chalking it up to experience.

        All this and I've only had it two weeks. This sucks.

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        • #5
          Re: Problems reaching top speed in my SL900, low end stutter as well...

          The 900 Is A Generally Reliable Polaris Compared To The 650-750 Motors. I Would Say You Have Carb Issues With Your Description Of The Rpm At 5600 Tops. If You Decide To Keep And Replace The Engine Be Sure To Go Through The Carbs Completly To Avoid Any Damage To The New Engine. Also From The Pics Of Your Pump Your Stator Is Shot!!!. That Will Cause Major Low End Hole Shot Performance Issues. Purchase A Good Used Or New Stator Vane Assembly And Feel The Difference. Good Luck.
          WATERCRAFT SERVICES. PROVIDING THE RESIDENTS OF HOUSTON AND SURROUNDING AREAS WITH QUALITY WORK ON THEIR PWC AT A FAIR PRICE.

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          • #6
            Re: Problems reaching top speed in my SL900, low end stutter as well...

            Thanks WCS, I would assume it probably went lean on that 1st cylinder and just blew to pieces.

            If I do go through with this I'll have the carbs rebuilt and go through all the lines to make sure there's no blockage of any kind.

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            • #7
              Re: Problems reaching top speed in my SL900, low end stutter as well...

              Your Assumption Is Correct. Good Idea To Check The Entire Fuel System. Sounds Like Your On The Right Track.
              WATERCRAFT SERVICES. PROVIDING THE RESIDENTS OF HOUSTON AND SURROUNDING AREAS WITH QUALITY WORK ON THEIR PWC AT A FAIR PRICE.

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              • #8
                Re: Problems reaching top speed in my SL900, low end stutter as well...

                I wonder if I didn't do any damage to the actual cylinder walls if I could get away with just replacing that piston w/o overboring? Ever heard of a case like that?

                I won't really be able to tell the damage till tomorrow, had alot of trouble getting the head cover off after removing the four bolts (any tips on that?).. seems like its stuck.

                Comment


                • #9
                  Re: Problems reaching top speed in my SL900, low end stutter as well...

                  You Can Replace The Bad Piston Only If You Choose To Do That. The Only Problem With That Is The Potential For Foreign Material From The Damaged Piston Contaminating The Lower Crankcase Area. Such As Crank Bearings. The Only Way To Be Sure You Are Safe With Only A Top End Repair Is To Totally Disassemble The Engine And Inspect The Crank For Any Damage. Remember The Melted Aluminum Went Somewhere. Some Will Be Exited Through The Exhaust But Never All Of It. If Your Cylinder Is Not Damaged And Within Specs Go Back With A Stock Piston After A Good Hone.
                  WATERCRAFT SERVICES. PROVIDING THE RESIDENTS OF HOUSTON AND SURROUNDING AREAS WITH QUALITY WORK ON THEIR PWC AT A FAIR PRICE.

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                  • #10
                    Re: Problems reaching top speed in my SL900, low end stutter as well...

                    Thanks WCS, it would be nice if that would work out. We'll see after disassembly :)

                    Wish there were some nice folks like yourself and dale jet sports around that I could trust to take it to. Seems not many shops around here are very inclinded to PWC's.. and go figure, this is Florida!

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                    • #11
                      Re: Problems reaching top speed in my SL900, low end stutter as well...

                      I Hear That Alot. Especially From People Who Had The Horrible Dealer Experiances. These Forums Are Great For The Do It Yourselfer. If You Are At All Mechanically Inclined Do This Job Yourself. Get A Factory Service Manual For All The Specs. Sbt Has A Page Dedicated To Engine Assembly Tips. This Will Help You. The Polaris Motors Are Not Too Terribly Hard To Reassemble For The First Timer.
                      WATERCRAFT SERVICES. PROVIDING THE RESIDENTS OF HOUSTON AND SURROUNDING AREAS WITH QUALITY WORK ON THEIR PWC AT A FAIR PRICE.

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                      • #12
                        Re: Problems reaching top speed in my SL900, low end stutter as well...

                        Yah, I've torn the top end of my 97 Z28 (kinda my racecar) apart, so I've got the tools and I can turn a wrench.

                        I have the Clymers manual, hopefully that'll work :)

                        How tough is carb rebuilding?

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                        • #13
                          Re: Problems reaching top speed in my SL900, low end stutter as well...

                          Not Too Bad. Look At The Sbt Video On Carb Rebuilding.
                          WATERCRAFT SERVICES. PROVIDING THE RESIDENTS OF HOUSTON AND SURROUNDING AREAS WITH QUALITY WORK ON THEIR PWC AT A FAIR PRICE.

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                          • #14
                            Re: Problems reaching top speed in my SL900, low end stutter as well...

                            Thanks again :D

                            Comment


                            • #15
                              Re: Problems reaching top speed in my SL900, low end stutter as well...

                              I did a complete top end after a piston skirt broke off and was completely digested by the engine. The shop cleaned out the lower end and claimed it didn't need to be rebuilt. I figured he was trying to save me some $, what a nice guy. I was worried the conn rods had too much lateral flex, but I don't work on these for a living. Maybe he had his eyes on the future, which was a seizure of the conn rod bearing (crank end) about 30 hours later. The total cost was more than double an SBT engine. There was a lesson for me there somewhere. There is a chance that the crank wasn't damaged and could last a long time, you gamble?

                              btw, could you post a side pic of your 97 sl900, I have a 96 and I want to simplify the color scheme of the decals, but the one I saw without any decals looked bad. Some of the 97's might work.

                              good luck.

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