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  4. CB750 scrambler project

CB750 scrambler project

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  • CalumC Calum

    Yes yes yes yes yes!

    Looks like an awesome project!

    Louis-DT-WRL Offline
    Louis-DT-WRL Offline
    Louis-DT-WR
    wrote on last edited by
    #9

    @Calum thanks, it's a bit of a crazy one. Time consuming too.
    Still need the engine but looking for a decent at a good price

    1 Reply Last reply
    0
    • pedrobatista10P pedrobatista10

      woow, looking great.

      your bottom forks what you used? powder coating?

      Louis-DT-WRL Offline
      Louis-DT-WRL Offline
      Louis-DT-WR
      wrote on last edited by
      #10

      @pedrobatista10 which part?
      The front forks aren in good condition.
      Swingarm is powder coated

      1 Reply Last reply
      0
      • pedrobatista10P Offline
        pedrobatista10P Offline
        pedrobatista10
        wrote on last edited by
        #11

        @Louis-DT-WR i mean where the calippers mount on the fork. that black is original? it looks great thats why i asked. i may need to do the same on my rs250 forks.

        Louis-DT-WRL 1 Reply Last reply
        0
        • pedrobatista10P pedrobatista10

          @Louis-DT-WR i mean where the calippers mount on the fork. that black is original? it looks great thats why i asked. i may need to do the same on my rs250 forks.

          Louis-DT-WRL Offline
          Louis-DT-WRL Offline
          Louis-DT-WR
          wrote on last edited by
          #12

          @pedrobatista10 it's original. Matt black.

          Got my front tyre on

          alt text
          alt text

          NINJAN 1 Reply Last reply
          3
          • Louis-DT-WRL Louis-DT-WR

            @pedrobatista10 it's original. Matt black.

            Got my front tyre on

            alt text
            alt text

            NINJAN Offline
            NINJAN Offline
            NINJA
            wrote on last edited by
            #13

            @Louis-DT-WR A twin disc set-up sweettttttt!!!!

            SEDUCED BY THE DARK SIDE!!!

            Louis-DT-WRL 1 Reply Last reply
            1
            • NINJAN NINJA

              @Louis-DT-WR A twin disc set-up sweettttttt!!!!

              Louis-DT-WRL Offline
              Louis-DT-WRL Offline
              Louis-DT-WR
              wrote on last edited by
              #14

              @NINJA yes indeed, it's the R6 front wheel

              NINJAN 1 Reply Last reply
              0
              • Louis-DT-WRL Louis-DT-WR

                @NINJA yes indeed, it's the R6 front wheel

                NINJAN Offline
                NINJAN Offline
                NINJA
                wrote on last edited by
                #15

                @Louis-DT-WR Are you building this for off-road on on-road use, or a bit of both?

                SEDUCED BY THE DARK SIDE!!!

                Louis-DT-WRL 1 Reply Last reply
                0
                • NINJAN NINJA

                  @Louis-DT-WR Are you building this for off-road on on-road use, or a bit of both?

                  Louis-DT-WRL Offline
                  Louis-DT-WRL Offline
                  Louis-DT-WR
                  wrote on last edited by
                  #16

                  @NINJA road and gravel tracks but mostly for the fun of building it.
                  The bikes too heavy for off-road and the suspension is too hard and not enough travel.

                  It's a bit of a madmax/walking dead type of bike

                  1 Reply Last reply
                  1
                  • Louis-DT-WRL Offline
                    Louis-DT-WRL Offline
                    Louis-DT-WR
                    wrote on last edited by
                    #17

                    Together they look like this.

                    Brat style
                    alt text

                    1 Reply Last reply
                    1
                    • Louis-DT-WRL Offline
                      Louis-DT-WRL Offline
                      Louis-DT-WR
                      wrote on last edited by
                      #18

                      Frame is now powdered
                      New tapered headset bearings installed.
                      Front end half on
                      New top bushes for the rear shocks to make it compatible.
                      Here's a little mock up.

                      Just waiting for my new bike lift to come.
                      I've got some pod filters on order + crank case vent filters.
                      Rejetted carbs using an online calculator (I will fine tune but as a starting point for the intake and exhaust mods)

                      I have a slightly nicer/longer seat now which will suit my stealth appearance.
                      alt text
                      alt text
                      alt text
                      alt text
                      alt text
                      alt text
                      alt text
                      alt text

                      It's very hard to visualize in your head but I think it's looking more or less like how I hoped

                      1 Reply Last reply
                      3
                      • Louis-DT-WRL Offline
                        Louis-DT-WRL Offline
                        Louis-DT-WR
                        wrote on last edited by
                        #19

                        After a bit of haggling I got an engine from a 12k mile bike (running) with warranty. I believe that is genuine, I will remove sump and cam cover to inspect+ comp test. And flush the lubrication system.

                        However the seller advertised it as a CB 750 nighthawk 1992 to 2003. It looks identical apart from what I couldn't see in the pictures.... It has No clutch arm!. Meaning it needs a hydraulic slave cylinder.

                        Also the electrics are not compatible with my loom, the cbx750 engine has loads more wires for shift lights, selector drum position etc.
                        I've now got to get the pulse generator sorted, source the main generator+ cover, starter motor+ cover.
                        The CBX has larger valves, maybe just exhaust?
                        Both engines have pros and cons.

                        Right enough spending for a bit 😅 luckily selling some old DT parts has really helped.
                        A bit of elbow grease and this engine really came up .... I haven't even painted it
                        alt text
                        alt text
                        alt text

                        Thinking about mounting the lights to this and using the slots for height adjustment.
                        alt text
                        alt text

                        markus.wM 1 Reply Last reply
                        2
                        • Louis-DT-WRL Louis-DT-WR

                          After a bit of haggling I got an engine from a 12k mile bike (running) with warranty. I believe that is genuine, I will remove sump and cam cover to inspect+ comp test. And flush the lubrication system.

                          However the seller advertised it as a CB 750 nighthawk 1992 to 2003. It looks identical apart from what I couldn't see in the pictures.... It has No clutch arm!. Meaning it needs a hydraulic slave cylinder.

                          Also the electrics are not compatible with my loom, the cbx750 engine has loads more wires for shift lights, selector drum position etc.
                          I've now got to get the pulse generator sorted, source the main generator+ cover, starter motor+ cover.
                          The CBX has larger valves, maybe just exhaust?
                          Both engines have pros and cons.

                          Right enough spending for a bit 😅 luckily selling some old DT parts has really helped.
                          A bit of elbow grease and this engine really came up .... I haven't even painted it
                          alt text
                          alt text
                          alt text

                          Thinking about mounting the lights to this and using the slots for height adjustment.
                          alt text
                          alt text

                          markus.wM Offline
                          markus.wM Offline
                          markus.w
                          wrote on last edited by
                          #20

                          @Louis-DT-WR loving the build so far. I fell in love with honda back in the late 90's after owning an nc30 for a couple of years. I must say for a "probably going to take a long time" project, (your words) lol. You have sure progressed quickly enough. At this rate you'll be riding it within the next week or two.

                          Louis-DT-WRL 1 Reply Last reply
                          0
                          • markus.wM markus.w

                            @Louis-DT-WR loving the build so far. I fell in love with honda back in the late 90's after owning an nc30 for a couple of years. I must say for a "probably going to take a long time" project, (your words) lol. You have sure progressed quickly enough. At this rate you'll be riding it within the next week or two.

                            Louis-DT-WRL Offline
                            Louis-DT-WRL Offline
                            Louis-DT-WR
                            wrote on last edited by Louis-DT-WR
                            #21

                            @markus-w thank you, I still need so many parts.

                            I have no experience with these bikes so i don't know how anything goes.
                            I need all the brake/ clutch hoses, front will have to be custom.
                            Levers, pedals, footrests, controls. Cables.
                            The biggest headache is the electrics.

                            I can't understand why it's a push pull cable on the diagrams when the CV carbs are sprung loads on the butterfly valves. Doesn't make sense.

                            This engine is all new to me, I can't get any information about what year and model bike it is. Engine code is RC17E.

                            I'm not entirely sure if this is a breather pipe or a return pipe ..,.
                            Can see it on diagrams, it looks like it bridges the two sides of the cylinder assembly.

                            alt text

                            markus.wM 1 Reply Last reply
                            0
                            • Louis-DT-WRL Offline
                              Louis-DT-WRL Offline
                              Louis-DT-WR
                              wrote on last edited by
                              #22

                              Wheels on.
                              alt text
                              alt text
                              alt text

                              1 Reply Last reply
                              0
                              • Louis-DT-WRL Louis-DT-WR

                                @markus-w thank you, I still need so many parts.

                                I have no experience with these bikes so i don't know how anything goes.
                                I need all the brake/ clutch hoses, front will have to be custom.
                                Levers, pedals, footrests, controls. Cables.
                                The biggest headache is the electrics.

                                I can't understand why it's a push pull cable on the diagrams when the CV carbs are sprung loads on the butterfly valves. Doesn't make sense.

                                This engine is all new to me, I can't get any information about what year and model bike it is. Engine code is RC17E.

                                I'm not entirely sure if this is a breather pipe or a return pipe ..,.
                                Can see it on diagrams, it looks like it bridges the two sides of the cylinder assembly.

                                alt text

                                markus.wM Offline
                                markus.wM Offline
                                markus.w
                                wrote on last edited by
                                #23

                                @Louis-DT-WR I think it is spring loaded as well with the push pull throttle cable or how else would the throttle shut off when you let it go? Or have I miss interpreted you?

                                Louis-DT-WRL 1 Reply Last reply
                                0
                                • markus.wM markus.w

                                  @Louis-DT-WR I think it is spring loaded as well with the push pull throttle cable or how else would the throttle shut off when you let it go? Or have I miss interpreted you?

                                  Louis-DT-WRL Offline
                                  Louis-DT-WRL Offline
                                  Louis-DT-WR
                                  wrote on last edited by
                                  #24

                                  @markus-w it only needs a single pull cable same as the DT but the diagram shows 2 cables.

                                  This pipe in the front of the engine must be a breather I can't see what else is would do.

                                  markus.wM 1 Reply Last reply
                                  0
                                  • Louis-DT-WRL Louis-DT-WR

                                    @markus-w it only needs a single pull cable same as the DT but the diagram shows 2 cables.

                                    This pipe in the front of the engine must be a breather I can't see what else is would do.

                                    markus.wM Offline
                                    markus.wM Offline
                                    markus.w
                                    wrote on last edited by
                                    #25

                                    @Louis-DT-WR you're probably right on it only needing one cable but U.S DOT requires two by law incase the spring fails or throttle slide sticks. Contrary to their name they don't actually push, when you shut off throttle the push cable actually pulls the throttle closed. As for the dtr having single cable maybe they weren't sold in U S.A or maybe that law comes in for bikes of a certain size/power. My 1989 nc30 had two.
                                    And yes it is a breather pipe, they sometimes are routed back into the carb manifold so any nasty emissions are burnt off. Hope this helps.

                                    Louis-DT-WRL 1 Reply Last reply
                                    0
                                    • markus.wM markus.w

                                      @Louis-DT-WR you're probably right on it only needing one cable but U.S DOT requires two by law incase the spring fails or throttle slide sticks. Contrary to their name they don't actually push, when you shut off throttle the push cable actually pulls the throttle closed. As for the dtr having single cable maybe they weren't sold in U S.A or maybe that law comes in for bikes of a certain size/power. My 1989 nc30 had two.
                                      And yes it is a breather pipe, they sometimes are routed back into the carb manifold so any nasty emissions are burnt off. Hope this helps.

                                      Louis-DT-WRL Offline
                                      Louis-DT-WRL Offline
                                      Louis-DT-WR
                                      wrote on last edited by
                                      #26

                                      @markus-w great thanks but I have a dt200wr which was sold in the US and that wasn't push-pull.
                                      The carbs to have slots for two cables day + choke cable.

                                      the CB 750 doesn't seem to have that breather pipe, but on this cbx750 it does.

                                      Brains hurting from all the learning on this build haha.

                                      I'm happy the rolling chassis is done.

                                      markus.wM 1 Reply Last reply
                                      0
                                      • Louis-DT-WRL Louis-DT-WR

                                        @markus-w great thanks but I have a dt200wr which was sold in the US and that wasn't push-pull.
                                        The carbs to have slots for two cables day + choke cable.

                                        the CB 750 doesn't seem to have that breather pipe, but on this cbx750 it does.

                                        Brains hurting from all the learning on this build haha.

                                        I'm happy the rolling chassis is done.

                                        markus.wM Offline
                                        markus.wM Offline
                                        markus.w
                                        wrote on last edited by
                                        #27

                                        @Louis-DT-WR my thirst for knowledge has got the better of me I've just done a bit of googling and apparently it's only four strokes have 2 cables because the extra vacuum created by a 4 stroke can cause the throttle slide to flutter and jam against the side of the body. That seems to me the most logical explanation so far.

                                        Louis-DT-WRL 1 Reply Last reply
                                        0
                                        • markus.wM markus.w

                                          @Louis-DT-WR my thirst for knowledge has got the better of me I've just done a bit of googling and apparently it's only four strokes have 2 cables because the extra vacuum created by a 4 stroke can cause the throttle slide to flutter and jam against the side of the body. That seems to me the most logical explanation so far.

                                          Louis-DT-WRL Offline
                                          Louis-DT-WRL Offline
                                          Louis-DT-WR
                                          wrote on last edited by
                                          #28

                                          @markus-w possible. The other thing with this engine is why does it have 2 oil fillers caps 🤷‍♂️ 1 says (don't open) but that's the sprocket side.
                                          In some pictures I see that's where the dipstick is on some bikes. My dipsticks on the clutch cover side like most bikes.

                                          Haynes don't do a cbx750 manual.
                                          Just going to persist working through all the small bits.

                                          Louis-DT-WRL 1 Reply Last reply
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