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  • What Next!

    Just purchased 2 1995 Polaris SL650Std. One runs perfectly the other is a problem. Problem is getting on top of the water. If I slowly increase the throttle I will get on top of the water and run good not great and as long as I do not come to a complete stop. It idles good and I can let off the throttle and open it wide open with small hesitation, just can't come to complete stop. Once stopped, it is slow getting up, but never dies will always idle good. To get up I have to slowly increase the throttle. Here is what I have tried. Ran Polaris carbon cleaner through the fuel. Changed all 3 plugs BRP7ES while cold. Started and ran great no problem for about thirty minutes then hard to get on top of the water. Changed the plugs when warm and still hard to get on top of the water. Changed the fuel pump still no difference. Made sure fuel hoses and filters were clear. Compressions reads the same as the one that runs great. Lookling at the plugs they appear to be running lean, so I took it out and adjusted the high speed in 1/8 increments with no success, also adjusted the low speed 1/8th at a time with no improvement. The only time it runs great is if I let it set over night and put in 3 new plugs and this only last 20 to 30 minutes. What do I try next?
    Last edited by rswann; 07-13-2004, 12:51 PM. Reason: Title Change

  • #2
    Re: What Next!

    i have a polaris 900 sl and i had a similar problem until i rebuilt the carbs, and
    don't be afraid to burn it rich it wont hurt the motor one bit , it will just make
    it last twice as long as everybody elses who run lean,extra oil is a good thing,
    the carbs are very basic to rebuild , get a service manual if you don't already
    have, there very handy.........hope this helps you.

    Comment


    • #3
      Re: What Next!

      I agree with Lance and you should look at the carbs especially the needles and seats etc. A rebuild of the carbs would be a good idea on a ski of this age. You also may want to check the reeds and see if they are not closing all the way.

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      • #4
        Re: What Next!

        It sounds to me it may be a pump problem since he can give it full throttle and it won't die and the rpm's come up. Ifyou have to slowley come to speed it is the pump cavitating bad.

        Not sure why it would work fine for a while after sitting overnite unless the gas tank vent is cloged and it won't allow fuel to the carbs because of a vacume in the tank. Next time it happends try unscrewing the cap and see if you here it pull air in.
        Providing mobile JetSki service to the Charlotte / Lake Wylie area.

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        • #5
          Re: What Next!

          I pulled the carbs and cleaned them took it to the lake and ran Great the first trip to the lake. Pulled the plugs and the front 2 plugs looked good. The rear (PTO) plug was Very lean and the GAP on that plug was almost closed. Reset the gap and turned the high speed out 1/4 turn. Next trip it ran good but not near as good as the previous trip it would not not reach top speed. Turned the high screw back in 1/4 and still no help. The only thing left is to close the gap on the plug, how would this help? But, the only time it has ran great was when the plug had very small gap. What does this tell me? Could someone explain how the Spark plug gap affects the way it runs? I also have an identical SL650 that runs perfectly. So I swapped the fuel ppumps and neither machin ran differently. How can I get full power back?

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          • #6
            Re: What Next!

            It sounds like to me that there is a very slight timing problem. This is how I see it...it runs good at first, since the elec. stator and flywheel are cold or slightly warm, then after 20mins. the problem starts, the stator/flywheel are now really warm, even hot. Remember things expand when heated and this may be enough to throw the timing off just a bit if it was on the edge when it's cool. This also explains why it works better with the smaller gap on the plug...it's compensating for the slight timing being off. I would check the stator and flywheel to make sure it is aligned properly...but don't ask me how to do it on this watercraft...good luck!
            Top End - A great place to be!
            00' SLX
            00' SLH
            98' SLTX

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            • #7
              Re: What Next!

              Have you tested the sparkplug leads and ends for continuity? Have you cleaned the ground wire connected to the motor plate? The spark plug boots should have 5k ohms resistance and if you check from the boot to the ground in the electrical box should be about 3k more so around 8k ohms resistance. Sounds like it may be electrical since it heats up and then doesn't run good. I would open the electrical box and go through it making sure everything is tightly connected. Do some basic continutiy and ground lead checks to see if everything is ok. You may want to start with taking the sparkplug boots off and cutting back the leads about 1/4 to 1/2 inch and screwing them back on to make new contact.

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              • #8
                Re: What Next!

                Thanks for the suggestions, I will the above recommendations. If nyone else has ideas let me know.

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                • #9
                  Re: What Next!

                  Pro racer, checked the plug wires from the boot to the watercraft ground, did not open electrical box yet. Here is what I found the back two plugs read just over 8K ohms and the front plug read as an open but the plug was still firing. After cutting this plug wire back 1/4" and put the boot back on it read approx 8K ohms just like the other 2. Here is my question, can the plug still fire it the plug wire is close to the boot but not touching? I will go test it tonight and see if there is improvement.

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                  • #10
                    Re: What Next!

                    I have seen where I took the plug boot off and it read open however the ski ran. I replaced them anyhow and it runs much smoother. It could arch across a small gap but obviously not the best scenario.

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                    • #11
                      Re: What Next!

                      Making progress, currently we have removed the problem of running poorly after warm up. The PWC does not bog down any more. It gets on top the water fairly good but takes a while to reach top speed and the top speed is 5-7 MPH slower than the good PWC. Here is where I am at, compared to the good PWC it is much slower at top speed and the slow PWC is not as quick as the good PWC. In a race between the two, with riders close in weight, the goood PWC gets on top of the water much quicker and is approximately 5-7 mph faster. The one thing the slow PWC seems to do better is come out of a 360 with more power. Also, other observations, the slow PWC seems that if there was more throttle it would go fatser, I checked the carbs to make sure they are fully open at WOT and they are. Also, after 2-3 hrs performance goes down and a change of spark plugs returns performance. Also, the slow PWC consitently has more water to drain after riding. The slow PWC idles all day and does not have any hesitation when going from no throttle to WOT and it never misses. Here is what I have done.

                      Cut a 1/4" of the plug wires, result no more bog and does not lose performance when the PWC warms up.
                      Cleaned the carbs and nothing changed.
                      Adjusted the carbs and any change to the carbs seems to reduce performance. The settings that give me the best performance are 2 turns out on the highs and 1 1/4 turns on the lows. 2 plugs look lean, front and rear, but, if I try to richen the mixture performance goes down.
                      Compression check shows both PWC reads between 108 and 112 for all cylindars.

                      This is getting very frustrating evryone wants to ride the faster PWC. Thanks to everyone providing suggestions, we are making improvements and I know someone is going to get me running good. So please make suggestions and I will keep trying them.

                      Comment


                      • #12
                        Re: What Next!

                        Assuming your jets (pilot / main) are correct for your altitude and conditions, and assuming you have your low speed and high speed screws set OK, then I would replace the fuel pump. Very much seems like carburetion (fuel issues). Get the engine to run so that you get the right color on on all 3 plugs.

                        Couple other things to consider... is the exhaust blocked in any way? Does the 'slow' PWC have a different intake grate - Does it have an issue with the impeller .. too much prop ... are you cavitating at all?

                        Comment


                        • #13
                          Re: What Next!

                          I assume the jets are the same, when I first got the PWC and changed the plugs it ran at top speed very close to the good PWC. I did swap fuel pumps between good and bad it did not have an effect on either machine. The thing I am unable to do is to get the plug color right. Both plugs that read open from the boot to ground, I fixed this and can't get either plug to turn chocolate brown they stay tan. If I try to richen the mixture I lose performance. The only difference between the 2 PWC is where the oil is fed into the carbs, the PWC that runs great has the oil feed from top of the carbs and the bad one is fed at the bottom of the cards right before the reeds.

                          I can't tell if the exhaust has any blockage, how do I check this? I am not familiar with the term cativating... can you explain? I talked to the person that I bought these from and he said the propellars were original.

                          Another thought I had was, am I getting too much oil? I read somewhere that too much oil would make the air gas mixture lean. How do Icheck/adjust oil?

                          Thanks for the suggestions.

                          Comment


                          • #14
                            Re: What Next!

                            To see if you have a blocked exhaust, I would swap the mufflers between the 2. When I say muffler, I mean the 'can', or 'silencer' towards the back... just the portion that is clamped in... don't pull the whole exhaust.

                            The best way I can describe cavitation is kind of like doing a burn out in a car. If you press the throttle on your jetski, and the RPMs climb very fast, but you really don't go any where for a bit, that would be cavitation. The impeller would not be biting water, it would be getting or creating air. In your case, causes of this are a damaged impeller / bad sealing intake grate / bad pump in most cases. I don't think you are cavitating though... so this is probably not the case.

                            Too much oil could be a problem too. There is a mark on the oil pump, and with the throttle fully closed (idle) the mark on the arm should be aligned with the mark on the body of the pump. Once you see the mark and the pump, you should be able to figure out if you are OK.

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                            • #15
                              Re: What Next!

                              You should get a factory service manual (not an off brand book)and adjust the carb settings accordingly. The correct way to read plugs is once you have the motor warmed up to operating temp, install new plugs and make a good long full throttle blast. Kill the engine(dont let off the throttle) and check them right there. That is the most accurate way to check plugs. Another thing you should check is the thermost/check valve assy. Rocks and other misc. can get stuck here and make the engine run hotter which can make the CDI cut back on the timing. I always just pulled those items out completely. Also do a visual inspection on the impeller, make sure theres no damage and its not bent. It may be stock but that doesnt mean it hasn't sustained any damage from rocks or something else

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