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Dynojet stage 3 tuning HELP

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    #31
    Before you found the fix, I read your posts and it sounded like you thought the bike was running very rich. I thought the opposite, that the problem you described was actually momentary fuel starvation, caused by a sudden drop in vacuum when you opened the throttle any quicker than the set up could handle. Pods will do that to CV's.
    I made a reply suggesting to richen the pilot circuit or jet needle circuit, sent the reply, then realized I missed two pages of your thread and you had found the fix. I deleted that post.
    If your nylon ring is similar to the ones used in the VM series carbs, it is quite thick and does force the jet needle downward and that leans the mixture at 1/5 to approx' 3/4 throttle. Removing it would richen the mixture by more than one needle clip position...much richer. On my VM's, it doesn't cause any issues, in fact, it needs to be installed or there will be metal to metal contact.
    I'm just glad you're happy with your bike now. Owning these old bikes can be frustrating when you factor in age, wear, previous owners, etc. At least with the GSR you're not alone. We've all been there. Have fun!
    And on the seventh day,after resting from all that he had done,God went for a ride on his GS!
    Upon seeing that it was good, he went out again on his ZX14! But just a little bit faster!

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      #32
      Originally posted by Kara25 View Post
      SUCCESS.! Thanks to Bill and everyone else who commented here! My thought about removing completely the plastic donut on top of the needle was correct. FINAL SETTINGS. 550E with K&N -RC2382 and 4-1 : stock pilot/150DJ mains/ and most important. Spring/OEM washer/E-Clip on 3rd groove/DJ washer/plastic cone/circlip. Bike runs like raped ape HOLY SÂ&@ÂÂT starts with normal amounts of choke(not fully open like before even in summer months) drops down to perfect idle 1100-1150 rpms and most importantly GREAT MIDRANGEÂÂ>TOP END. I should have spent the money earlier on the kit but itÂs never too late!
      I am about to configure the same setup to a '80 550L. Thank you very much for providing the final settings! I will report back with the progress

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        #33
        Hi mate.! My opinion is do all the modifications as the instructions of the kit say to do. Dont tap the air bits just push them in place with the little tool they provide and pour some glue which is also provided on the perimeter of each air restrictor thingy. Drilling the slides with the smaller bit of the 2 provided i think is essential just be careful cause the hole on the slides is at an angle and you have to follow the same pattern nice and easy dont rush the drilling. Its nerve racking i know but just do it slowly a little at a time. When i did everything the difference was crazy at least on my bike with a 4-1 marving racing exhaust and the dual K&Ns. Now the bike is not a 550 anymore i converted it to a 674cc using gs650 parts. Completely different machine performance wise jboge123
        GS674 Hybrid -1965 Vespa 90 -1958 BMW R26

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          #34
          Your bike looks great and I’m glad to hear it’s running well. Good to know some of those tips about the Dyno jet kit. I will have the same K&N’s but my exhaust is a MAC 4 into 1 with a performance baffle. Hopefully the settings you listed will be close to what I need for my bike which is otherwise a stock ‘80 550L

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            #35
            Logic says that if everything is in order you will notice the same benefits as i did last summer when i installed it. Thats the beauty of those DJ kits they take out the majority of the guess work for people who dont have tens of jets,needles etc laying around to make many many trial and error fittings and stuff. Only bad thing with those machines is that it NEVER ENDS if you really like your bike and want to keep it instead of getting a bigger cc motor you will constantly be purchasing upgrades and trying to squeeze out more from it. I am looking now on getting a set of mikuni RS carbs for the new engine. Did i say it never ends???
            GS674 Hybrid -1965 Vespa 90 -1958 BMW R26

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              #36
              Well I’m going to give it a shot by tuning my bike to the specs you listed out in your post. granted, you have a larger head than my stock 550, so I don’t know if that will have a significant impact on the settings. I hear you buddy.. there’s always one more thing to add hahah. I am trying to post a screenshot of my bike.. I modified it to turn it into a brat bike and I run TKC 80 knobby tires. I like to take it down dirt roads

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                #37
                No you got it backwards. The settings i have written here was when the bike was still a 550 with dual K&Ns and the 4-1 marving. So you will have no problems to get in the sweet spot by following them and then fine tune. After making the conversion only thing i had to do on the already dynojetted carbs from the 550 was swap out the main from the smaller of the 2 sets that was included on the kit and i was running as a 550 to the bigger ones to accomodate for the increase in cc. If memory is correct now i have the 155(?) Dynojet mains in there. The bigger of the two provided.
                GS674 Hybrid -1965 Vespa 90 -1958 BMW R26

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                  #38
                  Ah okay, very good to know! Thank you sir

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                    #39
                    Carbs were ultrasoniced today, all orings replaced, and stage 3 kit installed! I decided against drilling the slides for now just in case my bike were for some reason not work with the new air filters I figure I can atleast go back to stock. I did install the air correctors and the 150 main jets.

                    I followed the needle settings exactly as you described. With the E clip, did you put that on the 3rd slot (counting from the top of the needle downwards).

                    thank you

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                      #40
                      So? What are the results?
                      GS674 Hybrid -1965 Vespa 90 -1958 BMW R26

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                        #41
                        I’m waiting for the two petcock bolt gaskets to arrive this week and then I will connect everything and give her a go!

                        When you said the 3rd slot on the needle, you meant 3rd from the top?

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                          #42
                          Yes its the position that the instructions tell you to start with. If i remember correctly i had to go 1 step lower 4th slot to eliminate completely a lean bog at mid range at the end
                          GS674 Hybrid -1965 Vespa 90 -1958 BMW R26

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                            #43
                            Just for future reference, you can drill jets using SAE (not Metric), fractional, Letter and Number drills, as those drills go in increments of .001" of an inch, some even less. If you go too big, you solder the, and you drill the hole to a smaller size. Happy you got your bike right, I knew you would.

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                              #44
                              Well after 3 years of the bike having sit ( after not running) she fired up quite nicely with just half choke and about 10 seconds of working the starter.

                              However, I didn’t put the oil filter gasket on quite right and oil started pouring out (oops!). I also had a consistent leak from carb number 3 Although I completely rebuilt the carbs, ultrasoniced, new oring kit.. I did not wet bench test them.

                              none the less.. I’m quite pleased with how she started and fired all 4 cylinders using these new dual pods and the stage 3 DK kitz

                              ill keep you posted on how things come along once I get the carb leak corrected!

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                                #45
                                Leaks down there can be deceving. Did you replace the orings on the connecting T things between the carbs?? Those things need to be from a special material not common ones from the hardware store cause they dry out very quick and leak! Otherwise try tapping the bowl with the back side of a screwdriver it might be that the float is sticking momentarily. Yeah always a plus to fill the carbs OFF the bike to test i put them on a guitar stand fill them and let them sit for 30 minutes to be sure before bolting them on the bike . As for the filter gasket try next time getting some vaseline and working the oring on the groove with your fingers it will quickly take the correct shape and stay put in the groove while you bolt it downjboge123
                                Last edited by Kara25; 06-04-2023, 11:56 PM.
                                GS674 Hybrid -1965 Vespa 90 -1958 BMW R26

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