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  • Slight backfiring

    Hey guys did a post about hesitation and backfiring a couple of weeks back. Fully rebuilt the carb.Problem pretty much fixed. Still having a slight backfiring when on deceleration/coasting in gear. I have a baron jet kit 172.5 main 40 pilot pms 2 1/2 out needle clip 4th groove. Baron bak and v&h longshots. Any ideas would be appreciated. Thanks in advance

  • #2
    Air leak somewhere? Is AIS plugged/removed? Enricher plastic cover cracked? Manifold cracked/leaking?
    LET'S RIDE

    Comment


    • #3
      is it backfiring from carb or exhaust? I see a lot of longshots with a yellow spot in the middle of the bike. If yours has that discoloration on the pipe the exhaust joint under that spot needs to be cleaned up and tightened. An exhaust leak can cause a decel pop. If it is an intake pop try another 1/4 turn out on the pms.

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      • #4
        Exhaust side, already checked pipes from barrels to end of pipes no leaks. Something I just came across jet kit bak and longshots were in stalled when I purchased the bike many moons ago. While I rebuilt the carb pms was set 2 1/2 turns. I looked up the instructions on baron website and it said it should be set at 3 1/2 turns for that jetting. Seems that bike ran a tad rich but runs good for years. If you add a turn out doesn't that make run a bit more rich

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        • #5
          Lug Nut, ais removed enricher cover checked at rebuild intake manifold brand new

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          • #6
            turning it out does make it richer, The 3 1/2 turns in the instructions is for using a 35 pilot jet not a 40.

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            • #7
              Got it, so I wonder now why it has a 40 pilot jet and it's set at 21/2 turns. Maybe the the fat jet is making have that slight backfiring at deceleration/coasting in gear ??????

              Comment


              • davej
                davej commented
                Editing a comment
                The 40 pilot is the correct pilot jet. It took a lot of testing and a few dynos to figure out the the 35 pilot that comes suggested in the barons kit does not work as well as the 40 pilot.

            • #8
              longshot with or without baffles? How high rpm when backfire happens is it a high rpm decel?

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              • #9
                With baffles, it happens when your decelerating like coming up to light or another example is when your coming down a mountain road decelerating into a turn in gear or when your using the motor to slow you down. It almost like a blubbering popping sound. If that makes any sense. And when I said mountain road not at altitude.

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                • #10
                  Correction the main jet needle is at 5th groove not at the 4th like pervious mentioned

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                  • #11
                    Originally posted by Star415 View Post
                    Correction the main jet needle is at 5th groove not at the 4th like pervious mentioned
                    Move to 4th.... Set pms 2.5 turns out... Go test ride
                    LET'S RIDE

                    Comment


                    • davej
                      davej commented
                      Editing a comment
                      that would be the correct thing to do if it is a Barons 5 groove needle. If you would verify to us how many grooves on the needle you are using, 5 or 6 grooves?

                  • #12
                    Baron needle 6 grooves. Bike has baron bak, v&h longshots w/baffles. carb has in it right now 172.5 main 40 pilot clip 5th groove 2 1/2 turns out idle set around 900 rpm

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                    • #13
                      Barons needle is only 5 grooves. You have a different brand needle if it is 6 groove. It's probably a Speedstar needle. If it is a Speedstar you would leave the clip in th 5th groove and step up to a 177.5 or 180 mainjet

                      It could also be a dynojet needle with 6 groove. I'll post a sheet with needle measurements to determine what needle you have.

                      Comment


                      • Shotround
                        Shotround commented
                        Editing a comment
                        The barons kit I ordered earlier this year has 6 slots. Guess I now have a reason to acquire a caliper. Only indications it was a barons product was the instructions and the contents matched the list.

                    • #14
                      Click image for larger version  Name:	needle comparison chart.jpeg Views:	0 Size:	448.7 KB ID:	129308

                      Comment


                      • davej
                        davej commented
                        Editing a comment
                        You should be able to determine the brand by just measuring the point end with a digital caliper.

                    • #15
                      Will do this afternoon Thanks

                      Comment


                      • #16
                        Shotround, is the kit for a 1600 or 1700 motor just wondering. When I bought my R* in 2003 the guy that owned it told me that he used the kit that came with baron bak so I presume it's a baron needle.

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                        • #17
                          It’s a kit suitable for both engines per the description. I got it from the dealer. So I would believe the kit is legit.
                          Attached Files

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                          • #18
                            yep the kit works in both 1600 and 1700 carbs. The only difference is the size jets used.

                            Comment


                            • #19
                              They both have the same carb I was told mikuni bsr40. What year is your bike and what jets did you use and clip setting. Or did you go by instructions

                              Comment


                              • davej
                                davej commented
                                Editing a comment
                                The carbs are both BSR40 but they had a little modification in the starter jet on the 1700's.

                            • #20
                              After doing a little digging around I found that I may have mis-spoke about what needle you have. In the tech articles it claims that a barons needle does have 6 grooves.

                              I also found that there were at least 2 different kits made.1 kit was for 99-05 that the instructions called for clip in the 4th groove.
                              Then they come out with the BA2420RD 99-07 kit and the instructions say 4th groove for 04-07 and 5th groove for 99-03. I'm pretty sure that I have worked on carbs with 5 groove Barons needles. I wonder if the earlier kit was 5 groove and the later kit has 6 grooves.

                              Comment

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