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Dynojet stage 3 tuning HELP

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    Dynojet stage 3 tuning HELP

    Hello everyone. A month ago I decided to install a Dynojet stage 3 on my 550E with 4-1 exhaust and K&N dual oval filters RC-2382. Stripped soaked and rebuilt the carbs with new o rings drilled the slides and installed the Dynojet needles with the E clip on the third groove as instructed with the air adapter connectors also installed and used the 150 Dynojet mains instead of the 155s after seeing a similar thread from a 550 owner doing the same thing on his bike (pilots are stock as instructed from Dynojet)Also new carb boot o-rings and clamps while I was in there. Bike starts up very easy keeps beautiful idle carbs bench & vacuum synched to perfection and mixture screws 2.5 turns out from seated. So the problem is while the bike idles if I crack the throttle the motor briefly sputters/flutters and then clear revs up to 4500-5000 rpm. All testing is done while idling (don’t want to ride it yet after finding this problem and have to tear everything apart again) If I open the throttle gradually and slowly it doesn’t do that at all. Is it needle position related? Or maybe mixture screws need more tinkering? Weak 40 year old carb diaphragm springs? Please help I think I am very close to finally perfecting the whole system. Sorry for the long message tried to put all the info in!
    GS674 Hybrid -1965 Vespa 90 -1958 BMW R26

    #2
    Were the K & N's oiled w/their brand of filter oil?

    What kind of 4-1 exhaust?.

    Could the petcock not be providing enough fuel to meet the increased airflow of the K & N's?

    I would ride it to see where the hesitation actually is, noting throttle position & rpms.

    Then decide where the hesitation resides- pilot-needles-mains or the transition points between.

    Not sure what HP gains are claimed for a stock 550, with jet kit & pipe, but it might just be louder w/stumble over stock & maybe only some gains @ wide open throttle.

    Suppose there's always questions about valve adjustment, float height & if a too restrictive inline fuel filter is starving the carbs or if the vacuum line might not be attached to the petcock.

    Seems all 4-1's have a stumble somewhere when dealing with our era of bikes.
    GS\'s since 1982: 55OMZ, 550ES, 750ET, (2) 1100ET\'s, 1100S, 1150ES. Current ride is an 83 Katana. Wifes bike is an 84 GS 1150ES

    Comment


      #3
      Originally posted by Carter Turk View Post
      Seems all 4-1's have a stumble somewhere when dealing with our era of bikes.
      Mine doesn't. But I had mine jetted by a pro on a dynamometer.
      1982 GS1100E V&H "SS" exhaust, APE pods, 1150 oil cooler, 140 speedo, 99.3 rear wheel HP, black engine, '83 red

      2016 XL883L sigpic Two-tone blue and white. Almost 42 hp! Status: destroyed, now owned by the insurance company. The hole in my memory starts an hour before the accident and ends 24 hours after.

      Comment


        #4
        K&Ns oiled with their specific oil valves adjusted over 500kms ago all tests are done with external fuel tank but for years I have canceled the vacuum operation of the petcock by plugging the lines and using an in-line ON/OFF switch. Everything is in order on the bike I was riding it 1,5 month ago. I was using the <<getto>> method of restricting the air around the air filters using all stock components in the carbs. It was working all right up until 6500-6800 rpms where it would run lean and stop accelerating anymore like hitting an invisible rev limiter. So that’s why I decided to buy the kit and get it over with. I am baffled why when I open the throttle gently on neutral it revs strong but when I blip it or crack on it shows this hesitation. To shed more light the symptom reminds me when our of curiosity in the past I installed the K&Ns without restrictions and rode it around the block you can imagine that after the slightest opening of the throttle it was sputtering and wasn’t revving at all. Now it seems to do almost the same while stationary and while blipping or cracking the throttle. On smooth opening it revs very good with no symptoms.
        Last edited by Kara25; 05-17-2021, 01:39 AM.
        GS674 Hybrid -1965 Vespa 90 -1958 BMW R26

        Comment


          #5
          So after digging more in those forums I found out that over the years people with stage 3s found out that the Dynojet instructions on where to place the OEM washer and the DJ washer are actually wrong. DJ says. Spring -oem washer-dj washer-E clip-plastic donut-plastic cone-circlip. In reality some high regarded forum members stated that it actually the order is: spring-oem washer-E clip-DJ washer-plastic donut-plastic cone-circlip. Gonna swap the washers and see what happens!
          GS674 Hybrid -1965 Vespa 90 -1958 BMW R26

          Comment


            #6
            So installed the DJ washer on top of the E clip and still the same thing. Light feathering of the throttle in neutral produces sputtering. Steady slow opening of the throttle in neutral revs pick up normally. I am baffled. Any help will be appreciated!
            GS674 Hybrid -1965 Vespa 90 -1958 BMW R26

            Comment


              #7
              Originally posted by Rob S. View Post
              Mine doesn't
              I thought you were still horizontal guy or are you healed up & back in the saddle?

              Seems there's always a flat line or dip in the graphs for HP & Torque at a certain throttle opening, that I was referring to as a stumble.

              This was a pull done at the trackday mobile semi-truck awhile back, where dyno operator-Nels said my ignitor was breaking up a 7500 rpms, hence the broken

              lines on a tired/beaten engine.

              Jetting was done in unheated garage by this hack/me after many on/off sessions with carbs & fouled plugs, before discovering worn carb internals, such as oval

              emulsion tubes & broken air/fuel mixture needles.

              20210517_150607 by Carter Turk, on Flickr
              GS\'s since 1982: 55OMZ, 550ES, 750ET, (2) 1100ET\'s, 1100S, 1150ES. Current ride is an 83 Katana. Wifes bike is an 84 GS 1150ES

              Comment


                #8
                Originally posted by Carter Turk View Post
                I thought you were still horizontal guy or are you healed up & back in the saddle?
                Was horizontal, now vertical/diagonal. Trouble is, big red is in my brother's storage unit, and possession is nine tenths...

                "How about we come down this weekend and buy you a nice new shiny bicycle?"

                "I want my motorcycle!"

                Is that 115 rear wheel HP I see from a 550?!?
                Last edited by Rob S.; 05-17-2021, 07:15 PM.
                1982 GS1100E V&H "SS" exhaust, APE pods, 1150 oil cooler, 140 speedo, 99.3 rear wheel HP, black engine, '83 red

                2016 XL883L sigpic Two-tone blue and white. Almost 42 hp! Status: destroyed, now owned by the insurance company. The hole in my memory starts an hour before the accident and ends 24 hours after.

                Comment


                  #9
                  Originally posted by Rob S. View Post
                  Is that 115 rear wheel HP I see from a 550?!?
                  No, a 1229-1150, w/stock cams-valves-gixxer carbs-old yosh-k & n's, w/a lot of miles.

                  Not wanting to hijack thread, just trying to show that sometimes there are different lines compared to a stock graph & maybe that's what being felt (flat, dip in graph) when the throttle is wacked.

                  The lack of velocity stacks inside the air filter confuse the air flow entering the carbs. A random thought of course.
                  GS\'s since 1982: 55OMZ, 550ES, 750ET, (2) 1100ET\'s, 1100S, 1150ES. Current ride is an 83 Katana. Wifes bike is an 84 GS 1150ES

                  Comment


                    #10
                    I understand what you are hypothesizing carter and I know CVs are not know for their mind breaking response to sudden throttle changes but still seems weird I can’t imagine if it does that stationary how it’s gonna behave while starting from a standstill on the road. Guess today is the day that I test drive it
                    GS674 Hybrid -1965 Vespa 90 -1958 BMW R26

                    Comment


                      #11
                      Originally posted by Kara25 View Post
                      So installed the DJ washer on top of the E clip and still the same thing. Light feathering of the throttle in neutral produces sputtering. Steady slow opening of the throttle in neutral revs pick up normally. I am baffled. Any help will be appreciated!
                      Try the same test with the choke pulled a bit. If it improves you are likely lean right at that point, if it gets worse you are rich. At least this gives you some idea of which direction to look. Also, testing at idle in neutral is not really a good test because it will respond differently under load. I would do the choke test and then try a short ride to see how it goes with some load on the engine.

                      Note that you need to be over 1/8 throttle or so before you start getting the needles involved. Below that is all pilot circuit, so don't go adjusting the needles until you have test rode it some.


                      Mark
                      1982 GS1100E
                      1998 ZX-6R
                      2005 KTM 450EXC

                      Comment


                        #12
                        Mark speak of the devil. I am just outside my garage I took it for a short ride (the most it could carry me in that condition) up until 4000- 4.500 revs in first second or third things seem ok after that opening the throttle makes it sputter fall on its face horribly I pulled the choke and it got EVEN worse if you can believe that it almost killed the motor entirely.so I believe the needle must be raised meaning I have to move the E clip from the third groove from the top which DJ says is base setting on the second one from the top which will lean things out. Garage smells like gas galore so it must be pig rich. Tomorrow when it has cooled I will also take out the plugs to verify but I think they will be pitch black
                        GS674 Hybrid -1965 Vespa 90 -1958 BMW R26

                        Comment


                          #13
                          You got so much to learn about building power, none of the engine tuners here wanna write anything.
                          It starts on the inside, not the carburetors. Buy a book about building engine power.
                          "Only fe' collected the old way, has any value." from His Majesty O'Keefe (1954 film)
                          1982 GS1100G- road bike, body, seat and suspension modded
                          1990 GSX750F-(1127cc '92 GSXR engine) track bike, much re-engineered
                          1987 Honda CBR600F Hurricane; hooligan bike, restored

                          Comment


                            #14
                            Sorry bill wasn’t trying to build power anyway. Just wanted to jet my carbs 😂
                            GS674 Hybrid -1965 Vespa 90 -1958 BMW R26

                            Comment


                              #15
                              Ok, you say it idles ok and runs up to 4000 RPM, then floods.
                              I'm thinking you got too big main jets and the needles are too high.
                              Put in 1 size smaller jets that OEM to lean out WOT.
                              Drop the needles as far as adjustable to lean the midrange.
                              Test ride the bike.
                              "Only fe' collected the old way, has any value." from His Majesty O'Keefe (1954 film)
                              1982 GS1100G- road bike, body, seat and suspension modded
                              1990 GSX750F-(1127cc '92 GSXR engine) track bike, much re-engineered
                              1987 Honda CBR600F Hurricane; hooligan bike, restored

                              Comment

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