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  • #16
    I would go with the high volume and be done with it.

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    • #17
      Don't be cheap!

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      • #18
        I'll see what it costs and then decide. I'd rather go the high-flow also (probably will just to be safe), but don't have a huge bank account like you guys! :D

        I am glad I shouldn't haave to adjust carb settings.

        Thanks all.

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        • #19
          In addition to all that has been said i'll throw in this question as well. Being's as I'm on my second SBT motor for my 94 SLT 750, I NEVER want to deal with fuel starvation AGAIN. Once it gets warm out, i'll finish my motor installation and get her going again, however I want to replace the fuel pump with the triple output instead of having the OEM one and the additional one from SBT. Should I just goto my polaris dealer and tell them I have a 95 SLX780 and need the fuel pump? Also, from what I see above I am guessing that i'll have to mount the new pump elsewhere than the stock 750 one? I'll also by-pass the selector switch and ?? anything else you can think of? Thanks for all of your help in advance. :D

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          • #20
            You can mount it on the hull brace/rib (called the rh bulk head in the pic) behind the carbs as shown in the picture above. Either buy the Polaris bracket or make your own.

            The petcock by-pass and the triple outlet fuel pump will be fine for a rec boat.

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            • #21
              I also own a '95 SLT750. Last spring I purchased it as it came with a junk motor. As I took it apart, I found one cylinder was shot along with the piston, the rod went through the cases and also damaged the starter! Upon disassembly, I noticed one of the oil lines was empty (possibly clogged). After the rebuilt, I switched to premixing.
              I have been paying close attention to the associated problems with this engine and want to comment on the fuel starvation issue. I have put on 60 hours on this rebuilt and luckily no problems. I have read numerous articles related to fuel pumps whether adding or replacing. ( haven't seen any part numbers given) I called Polaris, and the service center while acknowledging the problem, states a few concerns to which I agree. There was a upgrade for the fuel pump, a diaphram kit. This new Polaris part is #3084222. The fuel pump remains the same. I would recommend changing this as cheap insurance, along with the rest of his suggestions which are: Keeping the fuel system clean of sediment, carbs clean, filters clean etc.
              I enjoy reading these message boards and thank all the responders for their insight.

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              • #22
                Sorry to anyone who might have been watching what I do in this fuel pump matter, I had some computer probs but got it going now.

                I haven't bought a new multi-outlet pump yet, but decided in the meantime I'd get a fuel pump kit for my stock pump to make sure it was working in top condition. Went to Seebold Sports in Osage Beach, MO (anyone in the MO/Lake Ozarks area with a Polaris and needing parts should go to them, they are quite helpful, talked w/a mechanic for a good hour) and got the pump kit for less than $10.

                Started my 750 briefly and ran it yesterday. Then took the pump off and rebuilt it. When I put the newly-rebuilt pump back on and fired up, I could tell the throttle response was somewhat crisper, **** near instantaneous.

                Don't know if I'll replace my pump with a multi-output yet, Mark the mecahnic at Seebold said he's rarely replaced pumps, that the main thing causing the problem is varnish and crud in the carbs (and also oil pump failures of course, they are not rebuildable though gotta buy new unit). I got to look at a prime example when I was in their "junker" area. This was in a model the same as mine, broken case just below the cylinder, he said it was one they couldn't send to SBT it was that bad. By the way, he said they use SBT when the season heats up and they need engines quickly and from a reliable source. Kudos to you, SBT!

                Last thing: I checked my compression yesterday, and got 120 lbs. in each of the 3 cylinders. Made my day, I think thats not bad for a 5-year old boat that's on the original motor.

                Ready for the water. Bring on spring.

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                • #23
                  I don't know if this is a waste. But I detailed a rather overkill setup last summer.

                  I'm moving web sites, but I'll see if I can post the information shortly if it could help.

                  http://www.errettet.org/fcm/images/2001fuel.jpg
                  That is the diagram of how the fuel routes in the 2001 Pro 785 carbs. It is much more efficent than the SL750 carb setup.

                  I'll post more on the high volume mikuni arrangement in a bit.

                  [ March 07, 2002, 10:05 AM: Message edited by: Skexies ]

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                  • #24
                    I am running Pro 785 44mm Mikunis and they come with 2 fuel pumps mounted to the carbs. Works well but I would recommend adding a 2nd. pulse fitting so that each pump has its own pulse line as I did and as the Pro785 has. For the least hassle, the triple outlet Mikuni high flow pump is the easiest option and very reliable.

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                    • #25
                      Mmm... running the pro 785 carbs too. Not seperate pulses though. Might need to look into that.

                      How much work is involved there?

                      -Skexies

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                      • #26
                        I used a Yamaha 62T style push in pulse fitting. You have to do it somewhere on the case, easier if the cylinders are off or the engine is out, but I already had everything together so I drilled into the lower section of the mag cylinder because that was the only place to fit an angle drill without removing cylinders or engine. I applied grease to the drill bit and went little by little cleaning off shavings and applying fresh grease several times. You don't want any shaving to fall into the crankcase thus the grease. I used JB weld around the fitting and tapped it in. I actually made it a tight fit and ruined the first fitting trying to get it in, so it's a good idea to get 2 as I did, just in case. You also have to rejet the 44mm Pro785 carbs to your application.

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                        • #27
                          I'm curious, how much did you need to change your jetting?

                          My acceleration is just a tad boggy when the engine is warm. It might be from a slightly rich idle. The plugs don't seem too radically bad and everything else seems decent, including the top end power and egt's. [shrug]

                          I was delaying messing with jetting until I figured out if I needed it post compression / porting change.

                          -Skexies

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                          • #28
                            I have 120 main and 110 low, but I am using a 92-93 SL650 dry pipe. The Pro carbs had 155 main and 105 low stock.

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                            • #29
                              Heh, that jetting probably explains a lot of the operation I had last season. Fuel consumption at long WOT runs was interesting, I was looking for the hole in the tank [img]/graemlins/winkanim.gif[/img] .

                              I got tired of bolting, painting and what not... so I threw it in the water as - was. EGTs were not horrible with a bit of adjuster tweeking so I ran with it.

                              I think I can drum up a 650 dry pipe somewhere, if this guy still has one sitting around. I was avoiding it last season because I was enjoying the water too much and contemplated a triple.

                              What bore are you running? My motor is still on the SBT +1mm standard engine. I heard that running bores over 1mm and raised compression heads could cause over heating with the 750's cooling capacity. Any news there?

                              Thanks again for the info!
                              -Skexies

                              [ March 15, 2002, 05:41 PM: Message edited by: Skexies ]

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                              • #30
                                I too have a 1 over SBT engine but I have the 780 and not the 750. I am also using modified stock heads with o-ring sealing. No overheat problems. The stock porting on the 780 is a little more radical than on the 750.
                                With the 650 dry pipe, be prepared to let it rev. Your Pro785 CDI will come in handy as will propping down to get on the pipe's power band.

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