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FJ1100 fork conversion

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  • Yep, a lot going on....

    First, if you're installing emulators, you don't need to drill that hole. The emulator takes over the function of the factory valve. That's why I completely removed the valve from mine; it would no longer work as designed. I also welded up the original 'adjustment holes'.

    As to the stops, I wasn't comfortable removing them as that's the lower limiter at full fork compression but leaving them in place as-is created several problems. As noted, the original 'circuitry' is such that on compression, oil is forced out the holes below the stops, through the 'anti-drive' valves, then back into the forks. If you remove the valves and block the holes, the oil has no path and the fork will be hydraulically 'locked'.

    The original number of holes and sizes in the damper rod was selected to control damping, but again, this function is now transferred to the emulator and is adjusted there. Hole size is no longer important as long as it's big enough to not restrict flow. In other words, too big is OK, too small isn't. Now, my emulators were designed for 39mm Harley forks and they specified four pretty large holes to be drilled in the OEM damper. These were larger than I was comfortable with drilling in the smaller FJ dampers, so I drilled the stop to allow flow past the stop using the OEM holes plus additional holes above the stop that would present the same or more opening than what the four larger holes represented. You could drill more than four holes above the stop for the same effect. One other reason I drilled the stops as that lets me use the lower fork screw as a drain hole; that screw is originally used to 'index' the damper rod so that the adjustment at the top is correct, no longer needed as the factory damper is gone. The holes allow the oil to drain past the stop.
    Fast, Cheap, Reliable... Pick any two

    '78E original owner - resto project
    '78E ???? owner - Modder project FJ forks, 4-piston calipers F/R, 160/80-16 rear tire
    '82 XJ rebuild project
    '80SG restified, red SOLD
    '79F parts...
    '81H more parts...

    Other current bikes:
    '93 XL1200 Anniversary Sportster 85RWHP
    '86 XL883/1200 Chopper
    '82 XL1000 w/1450cc Buell, Baker 6-speed, in-progress project
    Cage: '13 Mustang GT/CS with a few 'custom' touches
    Yep, can't leave nuthin' alone...

    Comment


    • Oops, I forgot about the springs....

      If the spacer is gone, you probably have aftermarket springs. Now, I'll respectfully disagree with Marty about the suitability of progressive springs. I personally prefer progressive-wound springs (I'm more into comfort), the damping is really a separate issue from the springs. Either will work if properly set up. From what I could find out, the stock FJ springs weren't very good and it was recommended that they be replaced as a first upgrade.
      Fast, Cheap, Reliable... Pick any two

      '78E original owner - resto project
      '78E ???? owner - Modder project FJ forks, 4-piston calipers F/R, 160/80-16 rear tire
      '82 XJ rebuild project
      '80SG restified, red SOLD
      '79F parts...
      '81H more parts...

      Other current bikes:
      '93 XL1200 Anniversary Sportster 85RWHP
      '86 XL883/1200 Chopper
      '82 XL1000 w/1450cc Buell, Baker 6-speed, in-progress project
      Cage: '13 Mustang GT/CS with a few 'custom' touches
      Yep, can't leave nuthin' alone...

      Comment


      • I have tried the Progressive springs and I did not like them with the emulators. I went with the HD emulators as Steve had mentioned and Sonic straight wound springs (.90 Kg/mm). The Mikes emulators will be too small for the diameter of the FJ springs. I got rid of the adjustable rebound damping and drilled one small hole in the side of the damper tube about an 1" or 2 down from the top. The bike runs like it is on rails as compared to before and I have put a good 35K on them with no problems.
        2H7 (79) owned since '89
        3H3 owned since '06

        "If it ain't broke, modify it"

        Comment


        • Do either of you guys have a link for the emulators you used? I'd like to take a look at them and com pair prices against the racetech emulators. This is the first I heard about the Mikes XS 650 emulators not working... That's a bummer.

          I think this is how I'm going to handle the whole anti-dive valve and the stops subject. Im keeping the anti-dive valve body but have gutted it.

          Here I the valve disassembled.



          Going to machine a disk to replace the one with the hole in it so the valve body is sealed an will allow the return flow path for the oil. I figured I could live with the asthetics of leaving the empty valve body on the lower fork leg.

          '79 XS11 F
          Stock except K&N

          '79 XS11 SF
          Stock, no title.

          '84 Chevy K-10 "Big Blue"
          GM 350, Muncie SM465, NP208, GM 10 Bolt with 3.42gears turnin 31x10.5 Baja Claws

          "What they do have is an implacable, unrelenting presence and movement that bespeaks massive power lurking behind paint and chrome. They don't wail like a screeching ninja, the don't rumble like a harley. They just growl like a spactic, stressed out badger waiting to rip your face off and eat your soul." Trainzz~RIP~

          Comment


          • What is the FJ fork diameter. JP Cycles sells Chinese knockoff emulators for Harleys. If the FJ is the same as Harley (41 mm?), you're in!

            Traxxion Dynamics sells the real deal for a little less than RaceTech and includes the necessary support to get it right. All sizes.
            Last edited by jetmechmarty; 08-21-2014, 09:24 PM.
            Marty (in Mississippi)
            XS1100SG
            XS650SK
            XS650SH
            XS650G
            XS6502F
            XS650E

            Comment


            • That's what I have is the Chinese knockoff emulator, 41MM, I think they were $50.

              Don't forget, there is nothing really special about these forks. The only advantage I've found is that they are much more stable, they clamp the axle on both sides, and the slider bushes can be easily replaced. Many guys with the FJ bikes ditch these forks for cartridge forks. If you use the 1200 lowers, you could probably fit some blue spot calipers with no adapter bracket needed.
              2H7 (79) owned since '89
              3H3 owned since '06

              "If it ain't broke, modify it"

              Comment


              • Originally posted by jetmechmarty View Post
                What is the FJ fork diameter. JP Cycles sells Chinese knockoff emulators for Harleys. If the FJ is the same as Harley (41 mm?), you're in!

                Traxxion Dynamics sells the real deal for a little less than RaceTech and includes the necessary support to get it right. All sizes.
                Thanks, I will look into them tomorrow. The FJ forks are 41 mm tubes. Steve said he used HD emulators, I'm not sure where they came from... I sent Phil a message and he said he ended up replacing the XS650 ones with proper sized ones. He said he had concerns with them seating properly in the damper...
                '79 XS11 F
                Stock except K&N

                '79 XS11 SF
                Stock, no title.

                '84 Chevy K-10 "Big Blue"
                GM 350, Muncie SM465, NP208, GM 10 Bolt with 3.42gears turnin 31x10.5 Baja Claws

                "What they do have is an implacable, unrelenting presence and movement that bespeaks massive power lurking behind paint and chrome. They don't wail like a screeching ninja, the don't rumble like a harley. They just growl like a spactic, stressed out badger waiting to rip your face off and eat your soul." Trainzz~RIP~

                Comment


                • Back in post 134, Steve's 39MM emulators are sitting down inside the damper rod, the 41MM ones I have sit on top of the rod. Also the Mikes ones I have with the spacer sit on top. I guess it will work either way, but Steve hasn't tested his yet.
                  2H7 (79) owned since '89
                  3H3 owned since '06

                  "If it ain't broke, modify it"

                  Comment


                  • Originally posted by jetmechmarty View Post
                    What is the FJ fork diameter. JP Cycles sells Chinese knockoff emulators for Harleys. If the FJ is the same as Harley (41 mm?), you're in!

                    Traxxion Dynamics sells the real deal for a little less than RaceTech and includes the necessary support to get it right. All sizes.
                    Are you sure it was JP? I looked and they only had Race Tech... I'll continue searching.
                    '79 XS11 F
                    Stock except K&N

                    '79 XS11 SF
                    Stock, no title.

                    '84 Chevy K-10 "Big Blue"
                    GM 350, Muncie SM465, NP208, GM 10 Bolt with 3.42gears turnin 31x10.5 Baja Claws

                    "What they do have is an implacable, unrelenting presence and movement that bespeaks massive power lurking behind paint and chrome. They don't wail like a screeching ninja, the don't rumble like a harley. They just growl like a spactic, stressed out badger waiting to rip your face off and eat your soul." Trainzz~RIP~

                    Comment


                    • More reading from...

                      http://www.fjmods.co.uk/emulators.htm

                      Race Tech Emulators:

                      Are there any FJ specific installation requirements?

                      The RT Emulator that fits all FJs is part number FEGV S4101. The FJ forks can be broken down into two basic designs. The 84-90 model years with adjustable rebound damping, and the 91+ model years without adjustable rebound damping.

                      The 91+ years only require removal of the damper rods to drill the aforementioned holes in them. Once the damper rod is re-installed, the Emulators can be placed in the forks and you are ready to ride.

                      On the 84-90 model years, the top of the damper rod may need to be slightly modified to allow the Emulator to fit flush on top . I will allow Rich Baker to explain. Rich wrote these instructions after installing Emulators in his '90 FJ, and they were originally posted on the Yahoo FJ club.

                      "There is a rotating valve, with a D-shaped hole in the center of it, in the top of the damper rod. The rebound damping is adjustable by rotating this valve. The valve is inside the damper rod, and has 2 holes (one larger than the other) in it's side that line up with a larger hole in the side of the damper rod. Minimum rebound damping = large hole, medium rebound damping = smaller hole, and maximum rebound damping = no hole. These holes are 120degrees and 240degrees apart. A D-shaped rod extends down from the rebound adjuster in the fork cap, through the spring, to the rotating valve. You need to cut this rod about an inch from the fork cap's 'spring seat.' The rebound valve is held in the damper rod with a circlip similar to the fork's seals. I had to take my Dremel to the top of the rebound valve and remove some, but not all of the 'D' to clear the bolt/nut on the bottom of the Emulator (the nut clears, but the bolt sticking through, hits the flat of the D). By 'hogging out' the top of the 'D' in the rebound valve, you can now use the D-shaped rod and pliers to adjust the rebound damping, after removing the fork spring and Emulator." Thanks Rich, for allowing me to use these instructions here. If the Emulators fit flush on the top of your damper rod no modifications to the damper rod are required.

                      I should add that installing Emulators will disable the anti-dive system of the '84-'87 model years. On the anti-dive model forks your existing compression orifices are under the tapered spindle (AKA oil lock piece). The new compression holes you drill should be above the tapered spindle but as low as possible. This will mean you will have to ignore Race Tech's instructions and not drill out your existing compression holes, but drill 6 completely new ones. With new holes in place above the spindle, oil will now flow up the inside of the damper rod before being forced through the anti-dive assembly. Once the Emulators are properly installed you can either leave your anti-dive assembly in place or remove it and install a block off plate. Normally, when installing a block-off plate, you will need to machine a passage for oil to flow from one orifice to another. However, with Emulators installed you can install a flat block-off plate. The oil passage is not needed, as oil no longer flows through that part of the fork. This procedure is not as difficult as it sounds. Just remember to drill the 6 - 5/16" holes in the damper rod as low as possible, above the tapered spindle.

                      The Emulators that fit the FJ will add 12mm of effective length to the damper rod, so you will need to reduce your spring spacer length by the same amount. Race Tech recommends 15W fork oil, filled to 130mm below the top of the fork tube. This level is measured when the forks are fully compressed, and neither the springs nor the emulators are in the forks. Race Tech also recommends 2.5 turns of preload on the valve spring be used as the staring point. Final settings on the fork oil weight, level and spring preload may vary according to personal preferences.
                      '79 XS11 F
                      Stock except K&N

                      '79 XS11 SF
                      Stock, no title.

                      '84 Chevy K-10 "Big Blue"
                      GM 350, Muncie SM465, NP208, GM 10 Bolt with 3.42gears turnin 31x10.5 Baja Claws

                      "What they do have is an implacable, unrelenting presence and movement that bespeaks massive power lurking behind paint and chrome. They don't wail like a screeching ninja, the don't rumble like a harley. They just growl like a spactic, stressed out badger waiting to rip your face off and eat your soul." Trainzz~RIP~

                      Comment


                      • Wade, I got my 41mm emulators from Debrix Cycles, unfortunately they seem to have gone out of business.
                        2H7 (79) owned since '89
                        3H3 owned since '06

                        "If it ain't broke, modify it"

                        Comment


                        • Fork Damper Valve Set

                          If you know the fork size of the listed Harley models, you can determine fitment. This vendor also deals in Race Tech.
                          Marty (in Mississippi)
                          XS1100SG
                          XS650SK
                          XS650SH
                          XS650G
                          XS6502F
                          XS650E

                          Comment


                          • Originally posted by WMarshy View Post
                            On the 84-90 model years, the top of the damper rod may need to be slightly modified to allow the Emulator to fit flush on top . I will allow Rich Baker to explain. Rich wrote these instructions after installing Emulators in his '90 FJ, and they were originally posted on the Yahoo FJ club.

                            "There is a rotating valve, with a D-shaped hole in the center of it, in the top of the damper rod. The rebound damping is adjustable by rotating this valve. The valve is inside the damper rod, and has 2 holes (one larger than the other) in it's side that line up with a larger hole in the side of the damper rod. Minimum rebound damping = large hole, medium rebound damping = smaller hole, and maximum rebound damping = no hole. These holes are 120degrees and 240degrees apart. A D-shaped rod extends down from the rebound adjuster in the fork cap, through the spring, to the rotating valve. You need to cut this rod about an inch from the fork cap's 'spring seat.' The rebound valve is held in the damper rod with a circlip similar to the fork's seals. I had to take my Dremel to the top of the rebound valve and remove some, but not all of the 'D' to clear the bolt/nut on the bottom of the Emulator (the nut clears, but the bolt sticking through, hits the flat of the D). By 'hogging out' the top of the 'D' in the rebound valve, you can now use the D-shaped rod and pliers to adjust the rebound damping, after removing the fork spring and Emulator." Thanks Rich, for allowing me to use these instructions here. If the Emulators fit flush on the top of your damper rod no modifications to the damper rod are required..
                            I'd be a bit leery of leaving the existing rebound valve in place as noted. IIRC, the 'detents' for the valve are at the fork cap and once you remove the rod so the emulator fits, it's possible for the valve to rotate out of position. Now, it's been a long time since I was inside these forks and the details aren't clear about that, but that's something I'd look at....
                            Last edited by crazy steve; 08-22-2014, 01:47 PM.
                            Fast, Cheap, Reliable... Pick any two

                            '78E original owner - resto project
                            '78E ???? owner - Modder project FJ forks, 4-piston calipers F/R, 160/80-16 rear tire
                            '82 XJ rebuild project
                            '80SG restified, red SOLD
                            '79F parts...
                            '81H more parts...

                            Other current bikes:
                            '93 XL1200 Anniversary Sportster 85RWHP
                            '86 XL883/1200 Chopper
                            '82 XL1000 w/1450cc Buell, Baker 6-speed, in-progress project
                            Cage: '13 Mustang GT/CS with a few 'custom' touches
                            Yep, can't leave nuthin' alone...

                            Comment


                            • Originally posted by crazy steve View Post
                              I'd be a bit leery of leaving the existing rebound valve in place as noted. IIRC, the 'detents' for the valve are at the fork cap and once you remove the rod so the emulator fits, it's possible for the valve to rotate out of position. Now, it's been a long time since I was inside these forks and the details aren't clear about that, but that's something I'd look at....
                              The detent is not in the cap, its down in the top of the damper rod between it and the rebound valve. Last night I dropped the detent ball when I removed the damper valve from the rod and thought 'well, I wont be needing that anyways'.


                              Originally posted by jetmechmarty View Post
                              Fork Damper Valve Set

                              If you know the fork size of the listed Harley models, you can determine fitment. This vendor also deals in Race Tech.
                              Thanks!
                              Last edited by WMarshy; 08-22-2014, 02:35 PM.
                              '79 XS11 F
                              Stock except K&N

                              '79 XS11 SF
                              Stock, no title.

                              '84 Chevy K-10 "Big Blue"
                              GM 350, Muncie SM465, NP208, GM 10 Bolt with 3.42gears turnin 31x10.5 Baja Claws

                              "What they do have is an implacable, unrelenting presence and movement that bespeaks massive power lurking behind paint and chrome. They don't wail like a screeching ninja, the don't rumble like a harley. They just growl like a spactic, stressed out badger waiting to rip your face off and eat your soul." Trainzz~RIP~

                              Comment

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