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  • '81 Hard to start when hot

    Hey folks. I've only had my Eleven for a couple of days, and have already added almost 300 miles to the odometer. She runs like a pig with a rocket strapped to it!

    I noticed that after a long ride, the bike is sometimes hard to start if I let it sit for a few minutes. If I kill it and re-start it immediately, it's fine. If I let it cool off a bit, it's also fine..
    So it's just when it sits hot for a while. I can get it to restart pretty quickly if I crank it over with the throttle wide open. Idle is perfect, regardless of temperature.

    It's not that big of a deal, and my XJ650 does it too, but I figure there's probably something that could be done to improve this behavior.

    Any ideas? Thanks in advance!
    ----
    '81 XS1100SH "Hound of Basketville" - new project
    '81 XS1100H Venturer
    '81 XJ750RH Seca

  • #2
    This happens to most carbureted bikes. In the heat the fuel vaporizes after sitting a bit the air box fills with vapors and acts as if it is flooded.

    I have eliminated the octy on mine and now sometimes if I forget to shut off the fuel it will flood a little.

    Best thing I've found to do is if either of these things occurs is to hold the throttle wide open when cranking and it clears out and starts up pretty quick.
    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


    • #3
      So it's just nature of the beast... Thank you for the explanation.

      This makes me wonder though.. My XJ750 almost never does it, and the only difference on it is a slightly um.. unrestricted airbox (I cut the inlet open to about twice its original size), with a K&N filter. So maybe the vapors vent quicker because of that, minimizing the problem?


      peace

      Vlad
      ----
      '81 XS1100SH "Hound of Basketville" - new project
      '81 XS1100H Venturer
      '81 XJ750RH Seca

      Comment


      • #4
        Bob had the hard starting issue a couple of years ago on his XJ1100 during a ride in the summer heat. I assume that the 750 has an airbox similar to the 1100.

        Maybe the extra ventilation does help.
        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


        • #5
          You might try checking the gasket and pressure relief on the gas tank cap it can cause issues like this if bike pressurizes from heat but most times causes bike to act like its running out of gas at high speed.
          To fix the problem one should not make more assumptions than the minimum needed.

          Rodan
          https://www.youtube.com/watch?v=khm6...liHntN91DHjHiS
          1980 G Silverbird
          Original Yamaha Fairfing and Bags
          1198 Overbore kit
          Grizzly 660 ACCT
          Barnett Clutch Springs
          R1 Clutch Fiber Plates
          122.5 Main Jets
          ACCT Mod
          Mac 4-2 Flare Tips
          Antivibe Bar ends
          Rear trunk add-on
          http://s1184.photobucket.com/albums/z329/viperron1/

          Comment


          • #6
            Had the same problem with my 80 SG I replaced the carb float valve (needles & seats) and the problem went away. My bike can sit in the sun all day long and it will start right away even when I forget to shut the petcocks off.
            BDF Special
            80SG Vetter bagger 1196 Wiseco big bore kit, Mega Cycle Cams, slotted cam gears, ported and flowed head, bronze intake seats, Dyno Jet kit, Dyno coils and Mikes XS air pods, Venture cam chain adjuster,Geezer's regulator, Clutch mod, Mac 4 into 1 with custom built and tuned baffle, Oil cooler,MikesXS emulators mod.
            Dyno tuned to 98 hp at the rear wheel.

            Comment


            • #7
              Originally posted by tinman905 View Post
              Had the same problem with my 80 SG I replaced the carb float valve (needles & seats) and the problem went away. My bike can sit in the sun all day long and it will start right away even when I forget to shut the petcocks off.
              105 - 110 degrees Fahrenheit ambient?
              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


              • #8
                This factory float level settings we use doesn't help matters. Mine did the same from new, and it IS kinda the 'nature of the beast'. But' I've found playing around with actual FUEL levels for some time now, that a tad lower fuel level in bowl resolves that...tottaly.
                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


                • #9
                  It may resolve that problem but will create another, lean condition on WOT.

                  Choose the lesser of 2 evils. Vote.
                  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


                  • #10
                    Originally posted by BA80 View Post
                    It may resolve that problem but will create another, lean condition on WOT.

                    Choose the lesser of 2 evils. Vote.
                    Yeppers.......can be compensated SOME with idle mixture settings, but main circuit ends up a bit 'hungry'........definitely a 'catch 22'.
                    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


                    • #11
                      Well,

                      Mine hasn't had any problems starting hot or cold. I do have POD filters.
                      Sounds like we may have found a valid reason to have Pods vs. the Oem Airbox that gets flooded with evaporated gas fumes!? However, perhaps if folks would drill a few holes on the bottom of the OEM airbox in the center section may help reduce the saturation of the evaporating fuel fumes?

                      T.C.
                      T. C. Gresham
                      81SH "Godzilla" . . .1179cc super-rat.
                      79SF "The Teacher" . . .basket case!
                      History shows again and again,
                      How nature points out the folly of men!

                      Comment


                      • #12
                        My bike came with an air box with a hole in the center bottom but you need to clean and or replace the filter from time to time. I use the white AC filter material cut off a thin strip and role it to fit in.
                        To fix the problem one should not make more assumptions than the minimum needed.

                        Rodan
                        https://www.youtube.com/watch?v=khm6...liHntN91DHjHiS
                        1980 G Silverbird
                        Original Yamaha Fairfing and Bags
                        1198 Overbore kit
                        Grizzly 660 ACCT
                        Barnett Clutch Springs
                        R1 Clutch Fiber Plates
                        122.5 Main Jets
                        ACCT Mod
                        Mac 4-2 Flare Tips
                        Antivibe Bar ends
                        Rear trunk add-on
                        http://s1184.photobucket.com/albums/z329/viperron1/

                        Comment


                        • #13
                          Originally posted by TopCatGr58 View Post
                          Well,

                          Mine hasn't had any problems starting hot or cold. I do have POD filters.
                          Sounds like we may have found a valid reason to have Pods vs. the Oem Airbox that gets flooded with evaporated gas fumes!? However, perhaps if folks would drill a few holes on the bottom of the OEM airbox in the center section may help reduce the saturation of the evaporating fuel fumes?

                          T.C.
                          There again TC, trading one issue for another.

                          The cooler the air that you can get to the intake the more power the engine can produce. Drawing air from just above the crank case and behind the cylinders is perhaps hottest air around the engine. That's one of the reasons the air box snorkel goes up and back under the seat.

                          With pods there is more airflow but when your going down the street or highway feel down there around those pods and see how hot the air is.

                          Originally posted by ViperRon View Post
                          My bike came with an air box with a hole in the center bottom but you need to clean and or replace the filter from time to time. I use the white AC filter material cut off a thin strip and role it to fit in.
                          That's a drain hole Ron. So any liquids that might get in there for any reason will have a place to drain off.
                          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


                          • #14
                            I have a feeling she's running a bit rich.. I can smell it. Also, my mileage sucks.
                            I think the carbs are gonna have to come off this weekend. Perhaps the richness is making the problem worse.
                            ----
                            '81 XS1100SH "Hound of Basketville" - new project
                            '81 XS1100H Venturer
                            '81 XJ750RH Seca

                            Comment


                            • #15
                              Originally posted by stereomind View Post
                              I have a feeling she's running a bit rich.. I can smell it. Also, my mileage sucks.
                              I think the carbs are gonna have to come off this weekend. Perhaps the richness is making the problem worse.
                              That it will, if the pilot circuit is restricted.
                              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

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