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  • Big Bore standard muffler upgrade.

    Hi there,

    After fitting the 88cc big bore kit to a friends Z50 with a stock muffler we found the stock muffler is quite a restriction.

    I have been having issues with getting it tuned properly and this mod will help a lot.

    He wanted to keep the stock factory look so bought a new muffler when we did the resto.

    I will be using the old aftermarket muffler and turning it into a higher flowing muffler and exhaust.

    I have some 25mm OD by 1.2mmn wall tube and will be sand bending it to shape.

    I will use a combination of forms and heat to get the desired bends

    Then i will cut open the muffler and remove the original pipework and weld in the bigger bore tube

    I will also redesign/remove any restrictions inside the muffler to improve airflow.

    Here are some photos of what i have so far.

    Just waiting on a router bit to scallop out the form to 25mm to allow the tube to fit.

    More to follow!

    Cheers.


  • #2
    The aftermarket chinese copy exhausts are a bigger bore pipe and not as restrictive. If that helps
    Once I thought I was wrong, I was mistaken

    Comment


    • #3
      Originally posted by Peter View Post
      The aftermarket chinese copy exhausts are a bigger bore pipe and not as restrictive. If that helps
      Thanks for letting me know that Peter i will keep that in mind.

      Cheers.

      Comment


      • #4
        Have you seen the 10 speed road bike handlebar exhaust mod ,?
        its engine oil madge ,,,
        Your soaking in it ,,!!

        Comment


        • #5
          http://www.monkeybikeoz.com.au/forum...ike-handlebars
          Classic Honda 50's Australia - Visit our online store at - www.classichonda50saustralia.com.au

          PERFORMANCE, REPRODUCTION AND OEM PARTS TO SUIT OLD AND NEW HONDA AND OTHER 4 STROKE MINIBIKES AND MOTORBIKES INCLUDING KAWASAKI, YAMAHA AND SUZUKI.

          Parts to Suit: Honda Z50A, Z50J1, Z50JZ, Z50R, Z50JDM, Z50M, QA50, QR50, MR50, XR50, CRF50, ATC70, CT70, CZ100, MSX125 (Grom), ST70, SL70, XL70, TRX70, XR75, XR80, TRX90, Kawasaki KLX110 and Z125 models to name a few.

          Comment


          • #6
            That is so cool !

            Certainly save some time doing it that way.


            Comment


            • #7
              Hi there,

              Here are a few more photos of the exhaust being bent up.

              I welded up one end then filled the tube with dry compacted fine sand.

              I plugged the other end with a dowel wedge and tape.

              After clamping the form and tube to the bench we bent the tube round the form as far as it would go.

              There was a bit of deformation due to the softness of the wood but as you can see it's not too bad

              I will get the rest of this tight radius bent using LPG torch.

              Cheers.

              Comment


              • #8
                Hi there,

                Got a bit more done on the exhaust.

                Finished the bending of the header and cut open the muffler

                Made up a jig to hold everything roughly where it needs to be.

                I will tack weld everything first and check on the bike

                There is a silencer can inside,at the exit end, that you can see, and it is quite restricted.

                I will remove this and come up with something freer flowing.

                I managed to get the header pretty close to the original shape. This was important as i want to be able to refit the factory covers.

                Cheers.

                Comment


                • #9
                  Is that the JDM Honda 50 exhaust with the smaller tailpipe?
                  Classic Honda 50's Australia - Visit our online store at - www.classichonda50saustralia.com.au

                  PERFORMANCE, REPRODUCTION AND OEM PARTS TO SUIT OLD AND NEW HONDA AND OTHER 4 STROKE MINIBIKES AND MOTORBIKES INCLUDING KAWASAKI, YAMAHA AND SUZUKI.

                  Parts to Suit: Honda Z50A, Z50J1, Z50JZ, Z50R, Z50JDM, Z50M, QA50, QR50, MR50, XR50, CRF50, ATC70, CT70, CZ100, MSX125 (Grom), ST70, SL70, XL70, TRX70, XR75, XR80, TRX90, Kawasaki KLX110 and Z125 models to name a few.

                  Comment


                  • #10
                    Originally posted by Classic Honda 50's View Post
                    Is that the JDM Honda 50 exhaust with the smaller tailpipe?
                    Hi Jamie,

                    It has Musket NZ stamped on the silencer and i found Musket Mufflers NZ online.

                    Cheers

                    Comment


                    • #11
                      I have spoken to them a few times in regard to making a big bore version of their exhaust, interesting how they use what looks to be an internal exhaust rather than the labarynth set-up.
                      Classic Honda 50's Australia - Visit our online store at - www.classichonda50saustralia.com.au

                      PERFORMANCE, REPRODUCTION AND OEM PARTS TO SUIT OLD AND NEW HONDA AND OTHER 4 STROKE MINIBIKES AND MOTORBIKES INCLUDING KAWASAKI, YAMAHA AND SUZUKI.

                      Parts to Suit: Honda Z50A, Z50J1, Z50JZ, Z50R, Z50JDM, Z50M, QA50, QR50, MR50, XR50, CRF50, ATC70, CT70, CZ100, MSX125 (Grom), ST70, SL70, XL70, TRX70, XR75, XR80, TRX90, Kawasaki KLX110 and Z125 models to name a few.

                      Comment


                      • #12
                        i like watching everyone's homemade parts and mods and you cosmo have been busy lately making some great molds and parts, this is another good mod thats saves a bit of coin and gives you a bit of pride in what youve done. Babu is a ideas man too and has made some awesome parts....... about time he built another bike too!
                        You have two parts of brain, 'left' and 'right'. In the left side, there's nothing right. In the right side, there's nothing left.

                        Comment


                        • #13
                          Originally posted by Classic Honda 50's View Post
                          I have spoken to them a few times in regard to making a big bore version of their exhaust, interesting how they use what looks to be an internal exhaust rather than the labarynth set-up.
                          I think they would sell heaps if they made em'

                          I think i will do a series of baffle walls and a baffle type exit pipe

                          Cheers

                          Comment


                          • #14
                            Hi there,

                            Here are some more photos of the muffler / exhaust

                            I will go with a two chamber design and hopefully it wont be too loud

                            The rear baffle i will bend forwards and up a bit to allow more room in the second chamber and this should help with slowing sound waves down.

                            Cheers

                            Comment


                            • #15
                              Hi there,

                              A bit more progress on the muffler.

                              I added a second smaller pipe to increase flow

                              I then tack welded the outer cover on and taped up the join and fitted the system onto the bike to test the noise level

                              It sounded good with a bit of a bark, but not at all loud, so i will weld it up!

                              Cheers.

                              Comment

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