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650 only running on 2 cylinders

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  • #16
    Re: 650 only running on 2 cylinders

    Hello
    I think you are on track with the carb's. also
    I would pull of both pumps and get the triple from partsland or who ever.
    Can you let us new pwcrs how it went for you?
    I know it will help me!
    Well good luck!
    DryDock

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    • #17
      Re: 650 only running on 2 cylinders

      If you have "rings" on the adjuster needles, replace them. They cannot possibly work correctly when they have been overtightened and they have rings on them.

      Replace all three needles and seats with the new style Vitron tipped needles and seats.

      The SBT rebuild kits come with everything you need, including the pivot arms and filters, but not the adjuster needles nor the needles and seats.

      Check your compression.
      Check your reeds.
      Check the indexing of the crankshaft. ( with the center clyinder piston at TDC, the two end pistons must be EXACTLY the same depth in their bores, if not, the crankshaft is twisted and it will never run right).
      Check to see if you have strong spark at the sparkplugs.

      If all of that is good, you probably just need to rebuild the carbs and install the new needles and seats and adjuster needles.

      I will do it for you for $100 per carb, including parts, if you don't feel like doing it yourself.
      Bill O'Neal, owner of Watercraft Magic in Glendora California, www.watercraftmagic.com

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      • #18
        Re: 650 only running on 2 cylinders

        In the process of getting parts for rebuild. Have a few questions.

        1. Can anyone confirm that the stock jets used are #80 for the high speed and pilot jet (Mikuni SBN 38.) Information from the Clymer manual for this model. The ones in the carbs now are 56 HS and 76 P (probably part of my problem?)

        2. Synchronizing has become a thought as well. Looking at the butterflies in the carbs they all look like they move and stop in the same position. Is it necessary to have them snyced at a shop with the vaccum testers? How much does this typically cost?

        3. Have since added sta-bil to my tank because it will probably be sitting for at least another 2 months. This is my 1st tank still (break-in tank), can I assume this will be fine to run come spring time to finish my break-in? The ski has been properly winterized.

        The reeds are new as well, Boyesen dual stage power reeds, and are in mint shape. Thanks for all the help, Im determined to get this thing running right by spring...
        Got Wake!

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        • #19
          Re: 650 only running on 2 cylinders

          Have you tried taking the spark plug boots off of the wires and trimming them back about 1/2in to ensure you are getting a good connection? I trimmed and replaced the boots with NGK Coppercore boots and have not had a problem with spark since.
          Last edited by warfare; 12-28-2004, 11:43 AM.

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          • #20
            Re: 650 only running on 2 cylinders

            I cannot confirm that jetting, but it certainly sounds whacky to me, and Mikuni doesn't even make jets in 56 and 76 sizes.......

            I have never seen carbs jetted with the same size high speeds and low speed jets???

            The low speed jet size is written on the outer diameter of the jets on the sides of the jets, you must remove them to read the size. The high speed jet size will be on the top of the jet between the screwdriver slot. The low and high speed jets are located under the jet blocks inside of the carbs behind the diaphrams. I don't know what you are reading, but 56 and 76 is not a jet size....

            No you do not need to check syncro with a vacume tester. You back off the idle adjuster screw and adjust the linkage so all butterflys are fully closed evenly, and they open evenly. Then re-set the idle speed.

            You might be smarter to use that tank of gas in your car and start off with new gas after you finish fixing your ski.
            Bill O'Neal <br>
            WCM
            <a href="http://www.watercraftmagic.com"

            Comment


            • #21
              Re: 650 only running on 2 cylinders

              I had a similar problem on a SL750. It ran great until it got turned over in the water.

              Just no mid range. Problem solved by installing 3 carb kits and adjusting engine in water.. Seems like there were a couple of problems. (1)Corroded springs and trash. (2)Diaphrams that were leaking(no holes) and looked like metal flake in one carb filter screen.

              Must have dumped trash into fuel circuits while jet ski was up side down.Also at the about same time the new 3 output fuel pump refused to pump (found a small hair in it), but replaced with a new one.

              So it seems that carbs and fuel pumps are really dependent upon the small peanut fuel filter(that was not originally installed when I bought the ski)

              And the groves around the needles are not a good thing. They need to be replaced.

              Hope this helps someone.

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              • #22
                Re: 650 only running on 2 cylinders

                Your right, those were the wrong sizes. The highs are 95 and the lows are 75. I would have thought the Clymer manual was a pretty reliable source, where else can I get stock jetting info for a 92 650?
                Got Wake!

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                • #23
                  Re: 650 only running on 2 cylinders

                  according to the Polaris Factory manual: http://picpost.stewfamily.com/650%20carb%20settings.pdf

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                  • #24
                    Re: 650 only running on 2 cylinders

                    Clymer - reliable source in the same sentence is a joke.
                    Bill O'Neal, owner of Watercraft Magic in Glendora California, www.watercraftmagic.com

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                    • #25
                      Re: 650 only running on 2 cylinders

                      Okay, got them rebuilt and bolted on. Replaced all the adjusters with new t-handle ones and all the needles and seats. Replaced all o-rings/gaskets/filters with the ones in the SBT kit. Also rejetted to stock, 80 HS, 85 LS. Springs and arms were also replaced. I set adjusters to the stock settings I received in this thread. Also set sync on throttle and choke. Everything went fine until I tried to start it. Given that this is still my break-in tank (lots of oil), the fuel has sta-bil in it, and the block was full of fogging oil, anything would be hard to start. I noticed that one of the carbs (the mag one that has been the source of my problem since day one) was leaking fuel into the carb even when the engine wasnt running. I could watch it fill up and open the throttle and it would just dump right into the intake. The engine became flooded because of this and I pulled the carbs back off to troubleshoot. The only thing I could think of was a stuck open needle...but a brand new one? I pulled it apart, looked everything over...it all looked good, nothing wrong with the needle or the seat. Put them back together and reinstalled them back on the block. I had to run the rest of the flooded fuel out of the block before I could turn the fuel back on to test the carbs, it was definitely running on all 3 though. It ran for a total of maybe 5 minutes before it burned it all up (stopping in between of course to let the engine cool.) When it finally ran out, I turned the fuel on on and looked for the leak. It didnt seem to be doing it anymore so I started it and it fired right up. I sounded fine and idle was good so I shut the fuel off again to run everything out of the sytem. Re-fogged and put her away.

                      What would cause a carb to leak fuel when its not running. My problem was apparently the needle and seat, but why would this happen? For the most part my first carb rebuild was a success. I wont know how well though until I can get it on the water in the spring. God bless fuel injection. Thanks for all the advice everyone and I'll let you know what happens in the spring.
                      Got Wake!

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                      • #26
                        Re: 650 only running on 2 cylinders

                        Sometimes I have had a new diaphram hold the needle open a little and let it leak or a miss-allgined one. You can test them on the bench with a pop off gauge first before you put them in the ski. Make sure it holds pressure at 75% of pop off pressure and you should be good.
                        Providing mobile JetSki service to the Charlotte / Lake Wylie area.

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                        • #27
                          Re: 650 only running on 2 cylinders

                          You should have used the original spring and lever. When you changed to a new spring, it was lighter than the original and not will not shut off the fuel supply. This happened to me. My SBT kit came with two new springs, so I used the new one that looked the same as the old one. Engine filled up with gas. SBT told me to put the original spring back in. Worked fine after that.

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                          • #28
                            Re: 650 only running on 2 cylinders

                            Good point, I did use the new springs. All three levers looked exactly the same, flush with the rest of the carb body though. I'll see how she acts in the spring and swap them if i have problems. Thanks for the advice all.
                            Got Wake!

                            Comment


                            • #29
                              Re: 650 only running on 2 cylinders

                              Still not right…The first ten minutes of riding was actually much better than before the carb rebuild, better throttle response and smoother acceleration. I think the re-jetting helped a lot. It was definitely running on all 3 this time. Went back to shore to make a few minor adjustments; mag was a tad lean and PTO was a tad rich, so I adjusted the screws about ¼ turn. Off the water a total of 5 minutes maybe and couldn’t get it started again. Tried setting carbs back to their original state and that didn’t help. Pulled her home and back in the garage to troubleshoot. Spark was ok and there was definitely fuel. After about a half hour of trying, I noticed fuel squirting from the small hole in the new rectangle add-on fuel pump from SBT. Is that supposed to happen? Is it some kind of fuel blow-off or something? It finally started and sounded great, so I shut the fuel off and let it run out again. I think its still flooding itself from a leaky needle and seat or something. That or I have a pop-off problem and I can’t see it. So, once again it’s back in another local shop to be looked at. I've done all I can. I’ve read a lot of comments on the SBT carb rebuild kits, are they really that bad…I’m starting to think so. Anymore advice? Thanks again.
                              Got Wake!

                              Comment


                              • #30
                                Re: 650 only running on 2 cylinders

                                Well, in the end it came down to diaphragms holding the needles open. Ordered genuine Mikuni diaphragms and no more flooding. The ones I got in the kit from SBT were much stiffer and less flexible...the root of my problem. The carbs are finally right and it is running great on all 3 cylinders now. I also replaced the 2 fuel pumps with a triple outlet from Parker. Having some low RPM vibration problems now, but will post another thread. Great learning curve from all this if anything. Thanks for all the help and I hope others can benefit from this issue.
                                Got Wake!

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