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MIKUNI Choke plunger seat replacement and Air corrector jets for GS fours VM's

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    #16
    Eh, so do I understand this correctly; these worn seats cause the choke circuit to leak fuel?

    How to test? Cause mine sure as hell don't look like the provided picture. But I have observed a few of the described issues.
    #1: 1979 GS 550 EC "Red" – Very first Bike / Overhaul thread        New here? ☛ Read the Top 10 Newbie mistakes thread
    #2: 1978 GS 550 EC "Blue" – Can't make it a donor / "Rebuild" thread     Manuals (and much more): See Cliff's homepage here
    #3: 2014 Moto Guzzi V7 II Racer – One needs a runner while wrenching
    #4: 1980 Moto Guzzi V65C – Something to chill

    Comment


      #17
      Originally posted by roeme View Post
      Eh, so do I understand this correctly; these worn seats cause the choke circuit to leak fuel?

      How to test? Cause mine sure as hell don't look like the provided picture. But I have observed a few of the described issues.
      Yes! They go hard and distorted with age and depending on wear you can suffer anything from slight rich running, sooty plugs to very poor running, idling issues, loss of power and increased fuel consumption etc.
      It's tricky to test them ( apart from them being visually indented and hard ) but chances are they are most likely leaking to some degree if they are the rubber tipped type found in MIKUNI carbs and with the use of Ethanol fuel accelerating the seal materials degradation their function will only get worse.
      The one in the pic is from a VM slide carb with metering needle attached as used on early GS's and KZs but some don't have the needle as on some Yamahas etc.
      There is no downside to fitting new seals as i use ethanol resistant Viton which they originally didn't so won't degrade with fuel contact once done and then they can be ruled out of any future fuelling problems.
      I can do any rubber tipped plungers and originally developed this to repair the obsolete ones that are no longer produced.
      The plungers for some later machines may still be available from the dealers but chances are the seals are Nitrile and not Viton so will still develop problems with modern fuel..
      Last edited by zed1015; 09-22-2023, 06:17 PM.
      Mikuni Viton Choke Plunger Seat Renewal.
      VITON Choke plunger seals .KAWASAKI Z1,Z900,Z650,Z1000,Z1R,SUZUKI GS1000,GSXR,RF | eBay

      Air Corrector Jets for Mikuni VM 24, 26 and 28mm carbs .
      https://www.ebay.co.uk/itm/254380193...84.m1555.l2649



      sigpic

      Comment


        #18
        Ah, thanks for the clarification (Luckily, no ethanol fuel around here unless you specifically seek it out).
        #1: 1979 GS 550 EC "Red" – Very first Bike / Overhaul thread        New here? ☛ Read the Top 10 Newbie mistakes thread
        #2: 1978 GS 550 EC "Blue" – Can't make it a donor / "Rebuild" thread     Manuals (and much more): See Cliff's homepage here
        #3: 2014 Moto Guzzi V7 II Racer – One needs a runner while wrenching
        #4: 1980 Moto Guzzi V65C – Something to chill

        Comment


          #19
          This looks like a service I will be seeking out as my bike has most of the classic problems outlined. Sooty plugs, lower than expected mpg, etc., etc., etc.

          I will be in touch in the near future.
          Larry

          '79 GS 1000E
          '93 Honda ST 1100 SOLD-- now residing in Arizona.
          '18 Triumph Tiger 800 (gone too soon)
          '19 Triumph Tiger 800 Christmas 2018 to me from me.
          '01 BMW R1100RL project purchased from a friend.

          Comment


            #20
            Just wanted to say I had a great experience with Rob and his work. He rebuilt the choke plungers for my 1980 GS1000G. The bike had never run under my ownership, so I can't do a before and after comparison but the bike is running now after a full carb rebuild and it seems to be running great! I haven't even vacuum balanced the carbs yet and they already feel like they run like new. No idea if the choke plunger rebuild contributed to this, but it certainly hasn't hurt anything. Thanks Rob, for the peace of mind. He does good work.

            Comment


              #21
              Originally posted by alke46 View Post
              This looks like a service I will be seeking out as my bike has most of the classic problems outlined. Sooty plugs, lower than expected mpg, etc., etc., etc.

              I will be in touch in the near future.
              I sent mine to Rob yesterday, 12/17/21. I will report the results when the bike is road-ready again. That will be early in 2022 I hope.
              Larry

              '79 GS 1000E
              '93 Honda ST 1100 SOLD-- now residing in Arizona.
              '18 Triumph Tiger 800 (gone too soon)
              '19 Triumph Tiger 800 Christmas 2018 to me from me.
              '01 BMW R1100RL project purchased from a friend.

              Comment


                #22
                Just chiming in to say that I got my plungers back yesterday, just a couple of days short of one month round trip to the UK and now home.

                I'm not complaining. It's just the nature of the beast when trying to ship overseas and back during the holiday season. The USPS gets overwhelmed easily this time of year.

                Thanks for the service you provide Rob. They look like new. Almost too good to go back on the carbs.
                Larry

                '79 GS 1000E
                '93 Honda ST 1100 SOLD-- now residing in Arizona.
                '18 Triumph Tiger 800 (gone too soon)
                '19 Triumph Tiger 800 Christmas 2018 to me from me.
                '01 BMW R1100RL project purchased from a friend.

                Comment


                  #23
                  Originally posted by alke46 View Post
                  Thanks for the service you provide Rob. They look like new. Almost too good to go back on the carbs.
                  Thanks, Larry.
                  I always treat the plungers as my own and make sure they are returned the best they can be and as well as fitting the Viton seals i always clean, polish and straighten them etc first if needed which i don't mention as i consider that part of the service.
                  Shipping time worldwide USA , AUS , NZ etc is usually 7 to 10 days each way but i've had the odd one do it in 4 and then a couple have took a month due to busy holidays etc.
                  Every set has made it back home though which is the main thing..
                  Last edited by zed1015; 01-22-2022, 03:20 PM.
                  Mikuni Viton Choke Plunger Seat Renewal.
                  VITON Choke plunger seals .KAWASAKI Z1,Z900,Z650,Z1000,Z1R,SUZUKI GS1000,GSXR,RF | eBay

                  Air Corrector Jets for Mikuni VM 24, 26 and 28mm carbs .
                  https://www.ebay.co.uk/itm/254380193...84.m1555.l2649



                  sigpic

                  Comment


                    #24
                    Plungers to the rich and famous.
                    Latest batch of refurbed choke plungers and air corrector jets ( Main air jet conversion for VM carb banks running pods ) all packed ready for their return trip to the New Zealand workshops of a certain Mr Crosby ( and it ain't Bing ).
                    PICT0230.jpg
                    Last edited by zed1015; 05-12-2022, 03:30 AM.
                    Mikuni Viton Choke Plunger Seat Renewal.
                    VITON Choke plunger seals .KAWASAKI Z1,Z900,Z650,Z1000,Z1R,SUZUKI GS1000,GSXR,RF | eBay

                    Air Corrector Jets for Mikuni VM 24, 26 and 28mm carbs .
                    https://www.ebay.co.uk/itm/254380193...84.m1555.l2649



                    sigpic

                    Comment


                      #25
                      Just got round to fitting the plungers refurbished by Rob and they have transformed the slow running and idle of my GS550. Couldn’t get the bike to idle correctly previously and since having the seals done the carbs were easy to set up and now idles perfectly. Recommended!

                      Comment


                        #26
                        I failed to report back my findings after getting my bike back on the road. I am super satisfied with the results after putting it all back together.

                        To date I have put on almost 3,000 miles and I can tell you that EVERY TIME I stop, for stop signs, or just sitting in traffic my tach shows 1100, maybe 1200 rpms. It never fails and I believe I owe all of this to Rob and his service of the choke plunger seats.

                        Very satisfied customer and highly recommend this service to anybody that rides with these cv or vm carburetors.

                        Thanks again Rob.
                        Larry

                        '79 GS 1000E
                        '93 Honda ST 1100 SOLD-- now residing in Arizona.
                        '18 Triumph Tiger 800 (gone too soon)
                        '19 Triumph Tiger 800 Christmas 2018 to me from me.
                        '01 BMW R1100RL project purchased from a friend.

                        Comment


                          #27
                          Just got my set back from Robert. ABSOUTELY AMAZING is all i can say!!!! Each was polished to perfection and in its own individual tiny zip loc baggie. I enthusiastically fully recommend you take advantage of his services soon as possible.Many thanks to you Robert.
                          MY BIKES..1977 GS 750 B, 1978 GS 1000 C (X2)
                          1978 GS 1000 E, 1979 GS 1000 S, 1973 Yamaha TX 750, 1977 Kawasaki KZ 650B1, 1975 Honda GL1000 Goldwing, 1983 CB 650SC Nighthawk, 1972 Honda CB 350K4, 74 Honda CB550

                          NEVER SNEAK UP ON A SLEEPING DOG..NOT EVEN YOUR OWN.


                          I would rather trust my bike to a "QUACK" that KNOWS how to fix it rather than a book worm that THINKS HE KNOWS how to fix it.

                          Comment


                            #28
                            Just an update to say that i can now repair ALL classic and modern 4 stroke and 2 stroke rubber tipped choke plungers, not just Mikuni but also Keihin, Teikie, Dellorto etc.
                            Price remains the same for overseas postage.
                            UK post now up 50p to £3.50 due to increased RM postal rates.
                            Thanks.
                            Last edited by zed1015; 09-03-2023, 07:31 PM.
                            Mikuni Viton Choke Plunger Seat Renewal.
                            VITON Choke plunger seals .KAWASAKI Z1,Z900,Z650,Z1000,Z1R,SUZUKI GS1000,GSXR,RF | eBay

                            Air Corrector Jets for Mikuni VM 24, 26 and 28mm carbs .
                            https://www.ebay.co.uk/itm/254380193...84.m1555.l2649



                            sigpic

                            Comment


                              #29
                              What’s the cost in dollars?
                              V
                              Gustov
                              80 GS 1100 LT, 83 1100 G "Scruffy"
                              81 GS 1000 G
                              79 GS 850 G
                              81 GS 850 L
                              83 GS 550 ES, 85 GS 550 ES
                              80 GS 550 L
                              86 450 Rebel, 70CL 70, Yamaha TTR125
                              2002 Honda 919
                              2004 Ural Gear up

                              Comment


                                #30
                                Originally posted by gustovh View Post
                                What’s the cost in dollars?
                                V
                                Price Returned per set of four plungers worldwide is £61 which is around $75 at the current exchange rate.
                                Air corrector jets are £41 a set posted which is around $50.
                                Last edited by zed1015; 09-23-2023, 02:33 AM.
                                Mikuni Viton Choke Plunger Seat Renewal.
                                VITON Choke plunger seals .KAWASAKI Z1,Z900,Z650,Z1000,Z1R,SUZUKI GS1000,GSXR,RF | eBay

                                Air Corrector Jets for Mikuni VM 24, 26 and 28mm carbs .
                                https://www.ebay.co.uk/itm/254380193...84.m1555.l2649



                                sigpic

                                Comment

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