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  • #31
    I went through 3 sets of carbs and half a dozen jet configurations as well as pretty much every other tunable part before I found that it was the exhaust causing the issue since I put this engine in here.

    I pretty much know WTF.

    This engine is out of a Bob Jones 79F parts bike and I've never been into it other than the valve cover and the oil pan but I can tell you for sure it's an "exhausting problem".

    Read all about it here........ http://www.xs11.com/forum/showthread.php?t=44707
    Greg

    Everybody is a genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is stupid.”

    ― Albert Einstein

    80 SG Ol' Okie;79 engine & carbs w/pods, 45 pilots, 140 mains, Custom Mac 4 into 2 exhaust, ACCT,XS850 final drive,110/90/19 front tire,TKat fork brace, XS750 140 MPH speedometer, Vetter IV fairing, aftermarket hard bags and trunk, LG high back seat, XJ rear shocks.

    The list changes.

    Comment

    • #32
      Originally posted by BA80 View Post
      I went through 3 sets of carbs and half a dozen jet configurations as well as pretty much every other tunable part before I found that it was the exhaust causing the issue since I put this engine in here.

      I pretty much know WTF.

      This engine is out of a Bob Jones 79F parts bike and I've never been into it other than the valve cover and the oil pan but I can tell you for sure it's an "exhausting problem".

      Read all about it here........ http://www.xs11.com/forum/showthread.php?t=44707
      IMO, the "exhausting issue" was the end result of 'highest inch vacuum' setting of mixture screws instead of 'lean drop' method. Possible a pinch to high of actual fuel levels, not float levels, or a step overall to rich with the main jet change. Know the later was done intentionally to least keep a 'to lean' cond. from occurring since you normally roll LD rides on slab at.... lets just say 'a fast clip'.
      81H Venturer1100 "The Bentley" (on steroids) 97 Yamaha YZ250(age reducer) 92 Honda ST1100 "Twisty"(touring rocket) Age is relative to the number of seconds counted 'airing' out an 85ft. table-top.

      Comment

      • #33
        Originally posted by motoman View Post
        IMO, the "exhausting issue" was the end result of 'highest inch vacuum' setting of mixture screws instead of 'lean drop' method. Possible a pinch to high of actual fuel levels, not float levels, or a step overall to rich with the main jet change. Know the later was done intentionally to least keep a 'to lean' cond. from occurring since you normally roll LD rides on slab at.... lets just say 'a fast clip'.
        GEEZE BRANT!!!!!!! Gimme a break.
        Greg

        Everybody is a genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is stupid.”

        ― Albert Einstein

        80 SG Ol' Okie;79 engine & carbs w/pods, 45 pilots, 140 mains, Custom Mac 4 into 2 exhaust, ACCT,XS850 final drive,110/90/19 front tire,TKat fork brace, XS750 140 MPH speedometer, Vetter IV fairing, aftermarket hard bags and trunk, LG high back seat, XJ rear shocks.

        The list changes.

        Comment

        • #34
          Originally posted by BA80 View Post
          GEEZE BRANT!!!!!!! Gimme a break.
          For you.....from me......no break.
          81H Venturer1100 "The Bentley" (on steroids) 97 Yamaha YZ250(age reducer) 92 Honda ST1100 "Twisty"(touring rocket) Age is relative to the number of seconds counted 'airing' out an 85ft. table-top.

          Comment

          • #35
            You know as well as I do, IDLE MIXTURE has absolutely NOTHING to do with WOT. Don't be ridiculous.
            Greg

            Everybody is a genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is stupid.”

            ― Albert Einstein

            80 SG Ol' Okie;79 engine & carbs w/pods, 45 pilots, 140 mains, Custom Mac 4 into 2 exhaust, ACCT,XS850 final drive,110/90/19 front tire,TKat fork brace, XS750 140 MPH speedometer, Vetter IV fairing, aftermarket hard bags and trunk, LG high back seat, XJ rear shocks.

            The list changes.

            Comment

            • #36
              Here's the latest on the exhaust.

              Got me a brand new Mac Flare Tip 4 into 1 system because it's the only Mac system other that the 4 into 1 that has removable baffles so I could play with them and modify as needed.



              Put it on a test rode it.......the stumble at WOT was back again so I pulled the baffles out and tried it again. Stumble gone but ear bleeding loud.

              Here's what the baffles that came in it look like. Just like the baffle in the 4 into 1 but there are 2.



              Too restrictive for this particular engine for some reason. Had a 4 into 1 on the green 79 and it ran GREAT with no issues at all. Same carbs, same jetting, basically the same engine but it was a 3H3 and this one is a 2H7.

              This is the first mod on the baffles. A 1 7/8" perforated baffle with a 1 1/2" welded on the end to extend the legth of the muffler case. Both straight through design. This is the 1 7/8" I used in the front, the rear were the ones dbeardslee suggested from JP Cycle.



              Still had the stumble but not quite as bad.
              So, I had another set of 1 7/8" baffles in the homemade set I had been running so I wrestled them out of there, they fought hard but I won. , cut the smaller ones off and welded them on the end of the other larger ones. Packed them in SS wool packing and went for a ride.

              VICTORY

              These mufflers look mean and sound even meaner but are actually only about as loud as my Mac turnouts were.
              Stumble is gone and pulls hard to well over 100mph.

              Greg

              Everybody is a genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is stupid.”

              ― Albert Einstein

              80 SG Ol' Okie;79 engine & carbs w/pods, 45 pilots, 140 mains, Custom Mac 4 into 2 exhaust, ACCT,XS850 final drive,110/90/19 front tire,TKat fork brace, XS750 140 MPH speedometer, Vetter IV fairing, aftermarket hard bags and trunk, LG high back seat, XJ rear shocks.

              The list changes.

              Comment

              • #37
                Good to see and hear you got the exhaust system sorted to keep motor happy now!
                81H Venturer1100 "The Bentley" (on steroids) 97 Yamaha YZ250(age reducer) 92 Honda ST1100 "Twisty"(touring rocket) Age is relative to the number of seconds counted 'airing' out an 85ft. table-top.

                Comment

                • #38
                  Originally posted by BA80 View Post

                  Got me a brand new Mac Flare Tip 4 into 1
                  That should say 4 into 2. My bad.
                  Greg

                  Everybody is a genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is stupid.”

                  ― Albert Einstein

                  80 SG Ol' Okie;79 engine & carbs w/pods, 45 pilots, 140 mains, Custom Mac 4 into 2 exhaust, ACCT,XS850 final drive,110/90/19 front tire,TKat fork brace, XS750 140 MPH speedometer, Vetter IV fairing, aftermarket hard bags and trunk, LG high back seat, XJ rear shocks.

                  The list changes.

                  Comment

                  • #39
                    Kinda blows the whole "back pressure" theory out of the water doesn't it?

                    Here's some reading for the back pressure is NEEDED advocates......

                    http://forums.mightycarmods.com/show...why-it-s-wrong
                    Greg

                    Everybody is a genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is stupid.”

                    ― Albert Einstein

                    80 SG Ol' Okie;79 engine & carbs w/pods, 45 pilots, 140 mains, Custom Mac 4 into 2 exhaust, ACCT,XS850 final drive,110/90/19 front tire,TKat fork brace, XS750 140 MPH speedometer, Vetter IV fairing, aftermarket hard bags and trunk, LG high back seat, XJ rear shocks.

                    The list changes.

                    Comment

                    • #40
                      Update

                      Since modifying the mufflers I've always still had a slight stumble at WOT around 4 - 5K I couldn't sort out. Finally I found the answer!

                      Put in a set of plugs one step hotter plugs and started playing with the air gap. With those plugs and a gap of .035 the stumble is COMPLETELY gone.
                      Greg

                      Everybody is a genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is stupid.”

                      ― Albert Einstein

                      80 SG Ol' Okie;79 engine & carbs w/pods, 45 pilots, 140 mains, Custom Mac 4 into 2 exhaust, ACCT,XS850 final drive,110/90/19 front tire,TKat fork brace, XS750 140 MPH speedometer, Vetter IV fairing, aftermarket hard bags and trunk, LG high back seat, XJ rear shocks.

                      The list changes.

                      Comment

                      • #41
                        Good to hear you got the issue sorted.
                        81H Venturer1100 "The Bentley" (on steroids) 97 Yamaha YZ250(age reducer) 92 Honda ST1100 "Twisty"(touring rocket) Age is relative to the number of seconds counted 'airing' out an 85ft. table-top.

                        Comment

                        • #42
                          Originally posted by motoman View Post
                          Good to hear you got the issue sorted.
                          Spark wasn't hot enough. It came to me laying in bed one evening. Might be why I don't have a wife too. LOL
                          Greg

                          Everybody is a genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is stupid.”

                          ― Albert Einstein

                          80 SG Ol' Okie;79 engine & carbs w/pods, 45 pilots, 140 mains, Custom Mac 4 into 2 exhaust, ACCT,XS850 final drive,110/90/19 front tire,TKat fork brace, XS750 140 MPH speedometer, Vetter IV fairing, aftermarket hard bags and trunk, LG high back seat, XJ rear shocks.

                          The list changes.

                          Comment

                          • #43
                            Originally posted by BA80 View Post
                            Spark wasn't hot enough. It came to me laying in bed one evening. Might be why I don't have a wife too. LOL
                            There you go Greg. Go hotter on spark.
                            Skids (Sid Hansen)

                            Down to one 1978 E. Stock air box with K&N filter, 81H pipes and carbs, 8500 feet elevation.

                            Comment

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