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94 Slt 750

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  • 94 Slt 750

    I just replaced the motor with a complete engine from SBT and I have encountered some problems. When I get the engine to start it will not idle or take throttle. I have checked everything I could think of and even replaced the fuel pump to the 780 model. I messed with it a little today and have discovered something weird. I can adjust the idle enough to keep it running and then proceed to remove plug wires and this is what happens. When I remove the back plug wire nothing changes, when I remove the front plug wire nothing changes but when I remove the center one the engine dies. This is the same result whether I have the front and back plug wire off together or just remove the center one only. Now I have checked for spark and it is all there and I can hear it when I removed and put the plug wire back on.The spark looks the same on all 3. I have replaced the plugs with no change and I have done a compression check and they are all above 100. What is my problem?

    Thanks
    Scott

  • #2
    Re: 94 Slt 750

    :( Anyone!

    Comment


    • #3
      Re: 94 Slt 750

      I'd say 1 and 3 are not getting any fuel. Check your carbs.

      Comment


      • #4
        Re: 94 Slt 750

        The carbs have been completely rebuilt but I will check them again. That does seem like the only thing it could be.

        Thanks
        Scott

        Comment


        • #5
          Re: 94 Slt 750

          sure sounds like carb issues.

          Comment


          • #6
            Re: 94 Slt 750

            I believe I have ruled out the carbs. I just finished rebuilding them again for the second time with all new parts. I still have the same issues as stated above. Anybody have any ideas before I sink this thing!

            Thanks
            Scott

            Comment


            • #7
              Re: 94 Slt 750

              you say you changed the fuel pump. I'd pull a line at the rear carb, start it up, pour a little pre-mixed gas into the carbs (or at least fogging spray) and see if gas is flowing. Otherwise, perhaps dirty filter or clogged lines.

              Comment


              • #8
                Re: 94 Slt 750

                Could be 1 & 3 have spark but its a weak spark. Try removing the caps
                and trimming back the wires and reinstalling the caps

                Comment


                • #9
                  Re: 94 Slt 750

                  I trimmed the wires, swapped coils around in the box,checked resistance on stator per service manual and everything is in spec but I still have the problem on the back cylinder. This has to be carb related but I have rebuilt 2 times with all new parts so what do I check? I am going to swap outlets on the new 780 fuel pump and see if and outlet might be blocked tomorrow. Any other suggestions???

                  Thanks
                  Scott

                  Comment


                  • #10
                    Re: 94 Slt 750

                    No blocked outlets on the 780 pump and I have bypassed everything and I'm running a line directly from the fuel tank. I am still having the problem of the engine stalling (dying) from idle. I have adjusted the low speed jet so much that I think I have wore out the threads. I even went thru the carbs again to make sure everything is ok. I have read in other threads of others having this problem but no one posted a fix. How do you check timing on these things? Could this be my problem? Oh yeah, I still have the issue of pulling the back plug wire off the plug and the motor continues to run with no change while either of the other 2 plug wires it dies instantly!

                    HELP!!!
                    Scott :emoticonr

                    Comment


                    • #11
                      Re: 94 Slt 750

                      Update!!

                      I pulled the carbs as well as the intake again and this time I took a block of wood and sanded all the mating surfaces and removed all the paint. I reinstalled all the above and still had the same problem but this time when I turned out the low speed adjusters things got better. As of now it runs fine but the low speed adjusters are at 2 full turns out. I am taking it to the lake to fine tune tomorrow so I will see where they end up. How far out before you need to change jets and why would this be so different from a 1/2 turn. Can I find out what size bore this motor has without pulling the heads and measuring? Could SBT tell me over the phone by the order number or is this tracked?

                      Thanks
                      Scott

                      Comment


                      • #12
                        Re: 94 Slt 750

                        Check your popoff and make sure that there is a restrictor in the return line.

                        Comment


                        • #13
                          Re: 94 Slt 750

                          A restrictor? I haven't seen a restrictor! What does it look like? Where exactly does it go? Where can I get one and what size? This may be my whole issue!!

                          Thanks
                          Scott

                          Comment


                          • #14
                            Re: 94 Slt 750

                            All it is is a main jet shoved in the return line. Mine is hose clamped in about 3/4" back from the nipple on the carb on the return line to the tank. It acts like a fuel pressure regulator.

                            Good luck.

                            Comment


                            • #15
                              Re: 94 Slt 750

                              Update on the 750. I just replaced the stator assembly and I still have the same problems as stated above. I can now get the 3rd cylinder to fire but not all the time just occasionally. Top end is rough and I can only get it to about 4500 RPM. The only thing left to change is the CDI unit. Does anyone know of a way to check the CDI before I replace it. This is getting way to expensive, so far around $1500.

                              I have been reading that alot of 750 owners are having similiar problems. I would be interested in some of the solutions that others have found.

                              Thanks
                              Scott

                              Comment

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