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1992 Trophy 900 missing on low revs

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  • dave.stickels
    Hi all, Ideas please, got an early 900 trophy 68000 miles plus a few when it went through a period of breaking speedo cables, with a low (below 2000 rpm) miss
    Message 1 of 10 , Apr 26, 2013
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      Hi all,
      Ideas please, got an early 900 trophy 68000 miles plus a few when it went through a period of breaking speedo cables, with a low (below 2000 rpm) miss on one cylinder, in fact when cold it does not play at all. Raise revs above 2000 and it will kick in and immediatly go to 3000 rpm and run fine.
      1. Changed coils round, problem stays on same cylinder (3)
      2. Changed plugs
      3. Cleaned carbs out
      4. Checked all primary wiring
      5. Opened up idle speed screw on that carb

      Problem almost disapears when hot, and bike is as good as it always been, used almost every day in all weathers.

      Suggestions welcome!
      Many thanks
      Sticky.
    • a2
      A couple of guesses for you Still have water getting from the tank to the carbs particularly if you ran in reserve or prime. As the revs rise water droplets
      Message 2 of 10 , Apr 26, 2013
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        A couple of guesses for you

        Still have water getting from the tank to the carbs particularly if you ran in reserve or prime. As the revs rise water droplets can be lifted but as revs rise further this effect is overwhelmed by fuel.

        Vacuum or slider prob on one carb.

        Valve clearance has gone negative....

        A2



        --- In TriumphTrophy@yahoogroups.com, "dave.stickels" <stickels2@...> wrote:
        >
        > Hi all,
        > Ideas please, got an early 900 trophy 68000 miles plus a few when it went through a period of breaking speedo cables, with a low (below 2000 rpm) miss on one cylinder, in fact when cold it does not play at all. Raise revs above 2000 and it will kick in and immediatly go to 3000 rpm and run fine.
        > 1. Changed coils round, problem stays on same cylinder (3)
        > 2. Changed plugs
        > 3. Cleaned carbs out
        > 4. Checked all primary wiring
        > 5. Opened up idle speed screw on that carb
        >
        > Problem almost disapears when hot, and bike is as good as it always been, used almost every day in all weathers.
        >
        > Suggestions welcome!
        > Many thanks
        > Sticky.
        >
      • Greg
        Hi Dave, Clogged pilot jet on that carb. Greg
        Message 3 of 10 , Apr 26, 2013
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          Hi Dave, Clogged pilot jet on that carb.
          Greg

          --- In TriumphTrophy@yahoogroups.com, "dave.stickels" <stickels2@...> wrote:
          >
          > Hi all,
          > Ideas please, got an early 900 trophy 68000 miles plus a few when it went through a period of breaking speedo cables, with a low (below 2000 rpm) miss on one cylinder, in fact when cold it does not play at all. Raise revs above 2000 and it will kick in and immediatly go to 3000 rpm and run fine.
          > 1. Changed coils round, problem stays on same cylinder (3)
          > 2. Changed plugs
          > 3. Cleaned carbs out
          > 4. Checked all primary wiring
          > 5. Opened up idle speed screw on that carb
          >
          > Problem almost disapears when hot, and bike is as good as it always been, used almost every day in all weathers.
          >
          > Suggestions welcome!
          > Many thanks
          > Sticky.
          >
        • dave.stickels
          ... you ran in reserve or prime. As the revs rise water droplets can be lifted but as revs rise further this effect is overwhelmed by fuel. ... go with what I
          Message 4 of 10 , Apr 26, 2013
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            --- In TriumphTrophy@yahoogroups.com, "a2" wrote:
            >
            > A couple of guesses for you
            >
            > Still have water getting from the tank to the carbs particularly if you ran in reserve or prime. As the revs rise water droplets can be lifted but as revs rise further this effect is overwhelmed by fuel.
            >
            > Vacuum or slider prob on one carb.
            >
            > Valve clearance has gone negative....
            >
            > A2
            >
            >
            >
            > --Ok, thanks for that, I am an electrician so probally been tending to go with what I know best (all the stuff with wires on!) I always run to reserve before filling and had not thought about water in the fuel, come to think of it have noticed corrosion around the filler cap inside, will empty tank and clean out and check carbs again.

             Thanks
            Sticky- In TriumphTrophy@yahoogroups.com, "dave.stickels" stickels2@ wrote:
            > >
            > > Hi all,
            > > Ideas please, got an early 900 trophy 68000 miles plus a few when it went through a period of breaking speedo cables, with a low (below 2000 rpm) miss on one cylinder, in fact when cold it does not play at all. Raise revs above 2000 and it will kick in and immediatly go to 3000 rpm and run fine.
            > > 1. Changed coils round, problem stays on same cylinder (3)
            > > 2. Changed plugs
            > > 3. Cleaned carbs out
            > > 4. Checked all primary wiring
            > > 5. Opened up idle speed screw on that carb
            > >
            > > Problem almost disapears when hot, and bike is as good as it always been, used almost every day in all weathers.
            > >
            > > Suggestions welcome!
            > > Many thanks
            > > Sticky.
            > >
            >
          • dave.stickels
            ... Thanks, it does seem to point more to carb or fuel probs more than ignition, had a few probs with coils over the years so tended to lean to that area, will
            Message 5 of 10 , Apr 27, 2013
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              --- In TriumphTrophy@yahoogroups.com, "Greg" <gandrews@...> wrote:
              >
              > Hi Dave, Clogged pilot jet on that carb.
              > Greg
              >
              Thanks, it does seem to point more to carb or fuel probs more than ignition, had a few probs with coils over the years so tended to lean to that area, will check and let you know.
              Thanks
              Sticky
              > --- In TriumphTrophy@yahoogroups.com, "dave.stickels" <stickels2@> wrote:
              > >
              > > Hi all,
              > > Ideas please, got an early 900 trophy 68000 miles plus a few when it went through a period of breaking speedo cables, with a low (below 2000 rpm) miss on one cylinder, in fact when cold it does not play at all. Raise revs above 2000 and it will kick in and immediatly go to 3000 rpm and run fine.
              > > 1. Changed coils round, problem stays on same cylinder (3)
              > > 2. Changed plugs
              > > 3. Cleaned carbs out
              > > 4. Checked all primary wiring
              > > 5. Opened up idle speed screw on that carb
              > >
              > > Problem almost disapears when hot, and bike is as good as it always been, used almost every day in all weathers.
              > >
              > > Suggestions welcome!
              > > Many thanks
              > > Sticky.
              > >
              >
            • Greg
              Hi Dave, I had a good laugh on the suggestions the others sent in. We have all had our Trophys for a while and have had a problem or two as time goes bye.
              Message 6 of 10 , Apr 27, 2013
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                Hi Dave, I had a good laugh on the suggestions the others sent in. We have all had our Trophys for a while and have had a problem or two as time goes bye. Mine has 93,000 miles so a few things have come up over 10 years. The suggestions are all valid because that is what ultimately fixed our bikes. I just found it funny because if you have been reading the posts in this group for a time. A person could almost guess who will chime in with a suggestion and what it will probably be. Thanks A2, you made me laugh.
                So where to start? Cheap and easy I guess. Draining the float bowls is easy and costs nothing except a few ounces of fuel. My suggestion costs nothing, but pulling the carbs to get to the pilot jet isn't easy. Oh, I just measured a pilot jet it is .014 inch. How does Mikuni drill those small holes? I have a wire brush and the bristles are .0135 inch. Low throttle settings are the air screw and pilot jet circuit.
                Greg Andrews
                '96 900 BRG


                --- In TriumphTrophy@yahoogroups.com, "dave.stickels" <stickels2@...> wrote:
                >
                > Hi all,
                > Ideas please, got an early 900 trophy 68000 miles plus a few when it went through a period of breaking speedo cables, with a low (below 2000 rpm) miss on one cylinder, in fact when cold it does not play at all. Raise revs above 2000 and it will kick in and immediatly go to 3000 rpm and run fine.
                > 1. Changed coils round, problem stays on same cylinder (3)
                > 2. Changed plugs
                > 3. Cleaned carbs out
                > 4. Checked all primary wiring
                > 5. Opened up idle speed screw on that carb
                >
                > Problem almost disapears when hot, and bike is as good as it always been, used almost every day in all weathers.
                >
                > Suggestions welcome!
                > Many thanks
                > Sticky.
                >
              • Ed Johnson
                I can only laugh because 99% of carburetion problems are electrical or is it 99% of electrical problems are carburetion? Don t ask me how I know! (;-) *Ed J.
                Message 7 of 10 , Apr 27, 2013
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                      I can only laugh because 99% of carburetion problems are electrical or is it 99% of electrical problems are carburetion? Don't ask me how I know! (;-)
                  Ed J. 2001Triumph Trophy BBBB
                  On 4/27/2013 2:52 PM, Greg wrote:
                  Hi Dave, I had a good laugh on the suggestions the others sent in.  We have all had our Trophys for a while and have had a problem or two as time goes bye. Mine has 93,000 miles so a few things have come up over 10 years. The suggestions are all valid because that is what ultimately fixed our bikes. I just found it funny because if you have been reading the posts in this group for a time. A person could almost guess who will chime in with a suggestion and what it will probably be. Thanks A2, you made me laugh.
                  So where to start? Cheap and easy I guess. Draining the float bowls is easy and costs nothing except a few ounces of fuel. My suggestion costs nothing, but pulling the carbs to get to the pilot jet isn't easy. Oh, I just measured a pilot jet it is .014 inch. How does Mikuni drill those small holes? I have a wire brush and the bristles are .0135 inch. Low throttle settings are the air screw and pilot jet circuit.
                  Greg Andrews
                  '96 900 BRG
                  
                  
                  
                  
                   
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                • a2
                  Glad u r amused by the by. I had a lovely Suzuki from new and could hear the slightest misfire. I could also get the carbs and bowls off without upsetting the
                  Message 8 of 10 , Apr 28, 2013
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                    Glad u r amused

                    by the by.
                    I had a lovely Suzuki from new and could hear the slightest misfire. I could also get the carbs and bowls off without upsetting the contents in about 5 mins. I directly related some heavy rainfall with a slight misfire - whether from the fuel station or from some bike failing I never knew. But I could probably feel a 4mm droplet upwards. Though I never cleaned out the tank in 80000 miles.

                    I presume the droplet rattled around the bottom of the carb and picked up occasionally (possibly assisted by the road) the occasional miss would come in on full throttle just as the power band came in and disappear as revs rose to max.

                    How a droplet would tickle away for a 20min trip in town constantly and not get sucked away forever was a quandary and I might guess the vibration might have broken the water up to a more emulsion like form.

                    As I said I could spot the offending droplet and consequently remove it (later I would just drop the carb contents into a bowl.) and presto missfire gone for the season....

                    Since then I have pondered the mechanics of this particularly as a bit of water vapour in a hot cylinder doesn't seem significant and having sucked up a proportion of the water surely I would run out of water. I might guess and suggest the increasingly conglomerating water mass might have been significant.

                    Anyone know whether high frequency sonics could be generated in a carb size to smash up the droplets. Then I could run on a water fuel mix.....and the carb would be self cleaning.....

                    Ooh careful the fuel lobby will be around.....

                    A2





                    --- In TriumphTrophy@yahoogroups.com, "Greg" <gandrews@...> wrote:
                    >
                    > Hi Dave, I had a good laugh on the suggestions the others sent in. We have all had our Trophys for a while and have had a problem or two as time goes bye. Mine has 93,000 miles so a few things have come up over 10 years. The suggestions are all valid because that is what ultimately fixed our bikes. I just found it funny because if you have been reading the posts in this group for a time. A person could almost guess who will chime in with a suggestion and what it will probably be. Thanks A2, you made me laugh.
                    > So where to start? Cheap and easy I guess. Draining the float bowls is easy and costs nothing except a few ounces of fuel. My suggestion costs nothing, but pulling the carbs to get to the pilot jet isn't easy. Oh, I just measured a pilot jet it is .014 inch. How does Mikuni drill those small holes? I have a wire brush and the bristles are .0135 inch. Low throttle settings are the air screw and pilot jet circuit.
                    > Greg Andrews
                    > '96 900 BRG
                    >
                    >
                    > --- In TriumphTrophy@yahoogroups.com, "dave.stickels" <stickels2@> wrote:
                    > >
                    > > Hi all,
                    > > Ideas please, got an early 900 trophy 68000 miles plus a few when it went through a period of breaking speedo cables, with a low (below 2000 rpm) miss on one cylinder, in fact when cold it does not play at all. Raise revs above 2000 and it will kick in and immediatly go to 3000 rpm and run fine.
                    > > 1. Changed coils round, problem stays on same cylinder (3)
                    > > 2. Changed plugs
                    > > 3. Cleaned carbs out
                    > > 4. Checked all primary wiring
                    > > 5. Opened up idle speed screw on that carb
                    > >
                    > > Problem almost disapears when hot, and bike is as good as it always been, used almost every day in all weathers.
                    > >
                    > > Suggestions welcome!
                    > > Many thanks
                    > > Sticky.
                    > >
                    >
                  • dave.stickels
                    Thanks for all suggestions! Trophy now happy again, did strip and clean carbs and jets but think main problem was the fact that one of the little o rings that
                    Message 9 of 10 , Apr 29, 2013
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                      Thanks for all suggestions!
                      Trophy now happy again, did strip and clean carbs and jets but think main problem was the fact that one of the little o rings that seal the vaccum take off in the top chamber of the carb was sitting under the diaphram! Must have been like this for at least the 12 years ive had it, looked like it had sealed itself with carbon but all the cleaning I had been doing broke the seal. Cleaned up, popped o ring back in runs like a dream.
                      Thanks again
                      Sticky.
                    • gordon2xbbb
                      Thanks Sticky...for letting us know the upshot/outcome and such a happy ending - it s what we like to hear.. Cheers Gordon 2xBBB Stroud, Gloucestershire, UK
                      Message 10 of 10 , Apr 29, 2013
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                        Thanks Sticky...for letting us know the upshot/outcome and such a happy ending - it's what we like to hear..

                        Cheers
                        Gordon
                        2xBBB
                        Stroud, Gloucestershire, UK

                        --- In TriumphTrophy@yahoogroups.com, "dave.stickels" <stickels2@...> wrote:
                        >
                        > Thanks for all suggestions!
                        > Trophy now happy again, did strip and clean carbs and jets but think main problem was the fact that one of the little o rings that seal the vaccum take off in the top chamber of the carb was sitting under the diaphram! Must have been like this for at least the 12 years ive had it, looked like it had sealed itself with carbon but all the cleaning I had been doing broke the seal. Cleaned up, popped o ring back in runs like a dream.
                        > Thanks again
                        > Sticky.
                        >
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