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O.T ? - Harley sportster problem

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  • O.T ? - Harley sportster problem

    Before I lose the use of this computer can the Harley literate amongst you help out a friend of mine?
    Phil was a Jap bike rider, recently he purchased a '85/'86 883 supposedly with a 1200 kit, he bought it a couple of months ago, a bit shabby but all there. Its' history is clouded in respect to what exactly has been done to it and by who.

    Now the problem he has is,as relayed to me; when opening up through all gears it responds initially then "flattens out",no more accelleration. This happens no where near the rev limiter.
    He has changed ignition boxes, fitted my old HS40 carb, changed coils, I think he has checked the VOS ( not sure )

    Does anyone have any suggestions that may help Phil get his bike running well?

    Jeez, I have a sore head with a big lump on the back. I was being reckless in my wheelchair, running backwards fast, grabbed one wheel to spin 180, too much body mass cause I never made the 180. I went over backwards, OH SH*TE!!, tucked my head into my chest but it was no good, I WACKED my scone onto the pavement, sent me goodnight for a small time and I still feel slightly sick A bit of blood and an egg
    That will teach me

    Thanks you lot
    cheers, Ken

    [This message has been edited by speedy (edited 04-12-2005).]
    Ken.

  • #2
    Geez, Ken, slow down!!!

    Sounds like either too much air going in or not enough restriction going out.

    If the intake's been opened up (bigger carb, K&N filter, Screamin' Eagle, etc.) the jetting is probably too lean. Larger jets should help.

    If the exhaust's been opened up (baffles knocked out, aftermarket exhaust, straight pipes) installing torque cones in the pipes will help: http://www.cas4.com/samson_accessories.htm

    ------------------
    Barry Milton
    Barry Milton

    Comment


    • #3
      If he was riding a Jap bike before then there's probably nothing wrong. Jap bike starts accelerating at 6000 rpm, sportster quits accelerating at 6000 rpm
      THAT OLD GANG 'O MINE

      Comment


      • #4
        Hey Ken how a bout a set of chrome moly wheelie bars for your chair. Then next step is a nive small engine and youre off. Seriously sportster engines when fiddled with sometimes require a LOT of mAIN JET. sgO UP A COUPLE MAIN JET SIZES AND TRY HER OUT. iF IT FEELS BETTER GO UP ONE MORE SIZE. tHEN WHEN ITS RUNNING NOT BAD DO A FULL THROTTLE PLUG CHOP. wIND IT OUT IN THIRD OR SO AND KILL THE ENGINE AND PULL THE CLUTCH IN AT THE SAME TIME. tHEN PULL THE SPARK PLUGS AND CHECK THE COLOUR. iF ITS WHITE FATTEN HER UP A SIZE. aND SO ON .i WONDER IF THIS WILL HELP. i SURE HOPE SO. oOPS TIME FOR A MOOSEHEAD BEER. gOTTA GO.

        Comment


        • #5
          Have you checked the flint ?
          .

          Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



          Comment


          • #6
            Speedy,

            The carb is too lean in the low to mid range and the too rich accelator pump is covering up the problem. Thus when the throttle is twisted the accelator pump gets it going then when that fuel is used up the jet(either low and/or mid range depending upon RPM) is too lean to continue the engine to pull.
            Mikuni has a book on proper jetting:
            http://www.sudco.com/tool.html#002-999

            and S$S has a good tuning site describing which and how to change jets on their carbs. All carbs work the same way, just made alittle differant.:
            http://www.sscycle.com/temp/instruct...et/51-1012.pdf

            Differant exausts(differant restrictions and tuned for differant RPMs -due to length vs dia) have a major effect on V2s

            check for the obvious first like an intake leak.

            Also its probally the first ride of the year. and the bike/carb may be clogged up from sitting all year. Keep the tank filled to the top to reduce condensation wich =s RUST....

            Let us know what is wrong

            Comment


            • #7
              You've changed the carb and ignition box and it's still the same? I might look at the cam(s) timing? A stuck ignition advance?

              The first thing most guys do is put straight pipes on them, yes this does mess up the mixture but usually not so much as to keep the engine from revving.

              Does that bike have a CV carb on it? What have they done to the air cleaner? A K&N along with no mufflers will effect them.

              ------------------
              Gene
              Gene

              Comment


              • #8
                "Have you checked the flint ? "

                John, you must be thinking of the flint and steel ignitions used on the Villiers engines that powered all the cavemen's mechanical devices (about which the historical record seems quite lacking in information).

                cheers,
                Michael

                Comment


                • #9
                  I'm betting the fuel tank vent may be clogged.

                  If he backs off the throttle for a bit, then rolls it back on does the engine respond ok?
                  C9

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                  • #10

                    He needs to pull out the spark plugs and look at them... The answer is right there usually.

                    If it's lean, it probably needs a larger set of jetts, or the float level is probably too low at 6000rpm for the CV carbs..

                    -Adrian

                    Comment


                    • #11
                      Reminds me of a funny story.

                      My friend was working on an old 45 side valve harley. Got the old girl running and took it out on the road. Ran great up to about 30 mph, and then it would die. He rolled over to the side of the road, gave it a kick to start, and it fired up right away. Took it back on the road, same thing happened. The repeated several times, with Jim's frustration level increasing.

                      He came roaring back to the garage with a big s*&% eating grin on his face and his pant leg rolled up. Seems his pant leg got sucked into the carb when he got going fast enough, and choked the motor. We sure kidded the hell out of him about how long it took him to figure it out.

                      Comment


                      • #12
                        Assuming that it ran correctly at one time, I think I would look for:

                        Intake air restriction
                        Fuel flow restriction
                        Compression
                        Ignition timing
                        Ignition advance
                        Exhaust back pressure (too much or possibly not enough).
                        THAT OLD GANG 'O MINE

                        Comment


                        • #13
                          John Stevenson "Have you checked the flint ? "

                          "stone?"

                          From what Phil has told me the bike is advancing, you know, the advance mark is coming up in the window when the revs are brought up. All simple things first - The tank vent is clear, the carb is clean, the plugs appear Ok ( no rich / lean indication )no intake leak ( no backfire on the overrun )
                          This prob existed before he fitted my old Mikuni.
                          It was suggested that he might check the cams for correct timing. Well yesterday ( Tuesday )he pulled off the cover without removing the rocker arms ha ha. Consequently the cam gears slipped and he has no way of knowing if they were previously misstimed. Someone had previously put their own marks? on the cams which have no relation to the factory marks ( could these be cam I.D colours ).
                          I have too much on at home at the moment but will go over after the weekend with a degree wheel and check the cam timing if he hasn't sorted it before.

                          Update: I spoke to Phil today and he has reassembled the bike with the factory cam marks aligned. He ran it up last night ( Wednesday ) and there is a definite improvement although the on idle is now rough but if the cam/s were "out" originally this would not appear to be surprising I think. He will road test it after work tonight, so I will let you know what is up.
                          Thanks for your advice.

                          Wheelie bars are on the 'to do sometime'
                          list before I scone myself properly. The head feels Ok today, no more leaks

                          cheers, Ken
                          Ken.

                          Comment


                          • #14
                            The diaphram in the carb might be pinched , the throttle slide will not rise from the closed position if this is the case . Check it by removing the air cleaner cover , starting engine and trying to rev the engine while observing the action of the throttle slide.

                            Comment


                            • #15
                              This problem was there with the CV carb and also when the HS40 was substituted. The HS40 slide operates using spring and cables so that will not be the prob here.
                              All knowledge is good ( mostly )--thanks.

                              cheers, Ken
                              Ken.

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