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79 special engine into xj

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  • #1

    79 special engine into xj

    I am looking at picking up an engine w/carbs from a '79 xs1100sf. My bike is an '82 xj maxim. Shouldn't be a problem right? Besides the engine, what else will I need off the bike for my frame? Vaccuum advance,ect. The Idea is to make either my xj an 1179 or build the other. should I just ride mine and build the '79 engine or slap in the '79 and build the xj so I have the numbers frame and engine sync'd. The milage on my xj is 35K mile and the '79 is roughly the same. I think i'm getting a fair deal on the engine, so I'd like to look at the positives. (Positives, like when I screw up one engine I have another.) I would welcome any inputs including negitives on doing this. I have read alot of the engine swap threads, so I'm looking for what I might have missed or anyone's personal experience having done this.
    Thanks,
    Dan
    Last edited by barberad; 11-20-2008, 03:06 PM.
    Current Rides: '82 XJ w/Jardine 4-1's, GIVI flyscreen, '97 Triumph Trophy 1200
    Former Rides: '71 CB350, '78 400 Hawk, '75 CB550/4;
    while in Japan: '86 KLR250, '86 VT250Z, '86 XL600R, '82 CB450(Hawk II), '96 750 Nighthawk, '96 BMW F650
    Tags: None
  • #2
    The '79 has a different charging system, and ignition system. Easiest thing is get the engine, swap out the XJ parts into the '79, and ride it while you are doing the XJ engine. I would go the 1196 kit, as it's a little less money, and you WILL have a second set of barrels if you need them later.
    This is just MY opinion, and we ALL know about opinions.....
    Ray Matteis
    KE6NHG
    XS1100 E '78 (winter project)
    XS1100 SF Bob Jones worked on it!

    Comment

    • #3
      Yup, do just as DiverRay says. I did similar with my XJ1100.
      K. Johnson
      -1978 XS750SF - brought back from the dead with carb
      triple clean and boots
      -1982 XJ1100J - brought back from the dead by
      replacing motor after throwing #4 rod
      -1985 XJ750XN - shim job, oil change, ride. not bad for
      $500 including new rear tire.

      Comment

      • #4
        Yup.. use the alternator (Rotor and stator) and pickups from the XJ. Also, the XS motor has an oil presure sensor on the back of the motor by the oil tube that feeds the head. The XJ won't have anything to use this. If you use the oil pan from the XJ on the XS motor, you'll be able to re-attach the wire to it and keep that oil light off on the dash.

        On the carbs themselves, there's the enrichener rod you'll have to change out to be able to use the choke lever the XJ has on the handlebars. Otherwise, you'll have to just use the lever that comes with them and do it manually from the side of the carbs. I have also been told that the carb inlet bells on the early carbs are 52mm and that the XJ's are 54mm. Don't know for sure or if that will make any difference if using the XJ air box and boots.


        Tod
        Try your hardest to be the kind of person your dog thinks you are.

        You can live to be 100, as long as you give up everything that would make you want to live to be 100!

        Current bikes:
        '06 Suzuki DR650
        *'82 XJ1100 with the 1179 kit. "Mad Maxim"
        '82 XJ1100 Completely stock fixer-upper
        '82 XJ1100 Bagger fixer-upper
        '82 XJ1100 Motor/frame and lots of boxes of parts
        '82 XJ1100 Parts bike
        '81 XS1100 Special
        '81 YZ250
        '80 XS850 Special
        '80 XR100
        *Crashed/Totalled, still own

        Comment

        • #5
          Originally posted by trbig View Post
          Yup.. use the alternator (Rotor and stator) and pickups from the XJ. Also, the XS motor has an oil presure sensor on the back of the motor by the oil tube that feeds the head. The XJ won't have anything to use this. If you use the oil pan from the XJ on the XS motor, you'll be able to re-attach the wire to it and keep that oil light off on the dash.

          On the carbs themselves, there's the enrichener rod you'll have to change out to be able to use the choke lever the XJ has on the handlebars. Otherwise, you'll have to just use the lever that comes with them and do it manually from the side of the carbs. I have also been told that the carb inlet bells on the early carbs are 52mm and that the XJ's are 54mm. Don't know for sure or if that will make any difference if using the XJ air box and boots.


          Tod
          Could I just get away with re-attaching the XJ carbs to the XS motor? I have no airbox, I think the carb boots are the same. And were the XJ carbs also part of the XS evolution process as well? Not sure which other engines had the same carbs, haven't looked at the parts site yet.
          Dan
          Current Rides: '82 XJ w/Jardine 4-1's, GIVI flyscreen, '97 Triumph Trophy 1200
          Former Rides: '71 CB350, '78 400 Hawk, '75 CB550/4;
          while in Japan: '86 KLR250, '86 VT250Z, '86 XL600R, '82 CB450(Hawk II), '96 750 Nighthawk, '96 BMW F650

          Comment

          • #6
            If you aren't using an air box, the outlet side of the carbs are all the same.

            The XJ carbs may or may not work for you. I threw a set of XS carbs on mine one time and it did OK.. but ended up putting the XJ ones back on. The jetting is completely different on the XS versus the XJ carbs. Main jets on an XS may run in the 140's, and maybe a 42 for the pilot jets. XJ's go the other way.. .bigger pilots.. 47.5 stock, and smaller mains.. 112.5. I seem to remember the mains on the XS carbs I used as 110's and 120's.. the inside pair being different than the outside.

            All that said... replacing the enrichener rod is pretty simple.. a few set screws holding it in place. BUT.. there are a couple little spring loaded steel balls you need to be careful with on the rod. Easy to see and watch for.. as long as you don't let them shoot out.. lol. Just be careful and you won't have any problems. It sounds scarier than it is. If you can swap a motor, you can replace a simple enrichener rod.

            Tod
            Try your hardest to be the kind of person your dog thinks you are.

            You can live to be 100, as long as you give up everything that would make you want to live to be 100!

            Current bikes:
            '06 Suzuki DR650
            *'82 XJ1100 with the 1179 kit. "Mad Maxim"
            '82 XJ1100 Completely stock fixer-upper
            '82 XJ1100 Bagger fixer-upper
            '82 XJ1100 Motor/frame and lots of boxes of parts
            '82 XJ1100 Parts bike
            '81 XS1100 Special
            '81 YZ250
            '80 XS850 Special
            '80 XR100
            *Crashed/Totalled, still own

            Comment

            • #7
              My 1980 special is running XJ head and carbs. No problem mating with the airbox. A little WD 40 makes things easier, but I noticed no difference installing the originals or the XJ carbs. I just hold the enricher bar with my thumb while the engine warms up. May rig a choke wire some day, but the thumb works for now.
              1980 XS 11 Special: The King of Kong, 9th wonder of the world. Pacifico fairing, chopped shield, Yamaha hard bags, Diamond seat, T-Kat fork brace, XJ top end, YICS Eliminator, '80 carbs from Spyder Cycle Works, K&N Air filter, Fuse block, stainless steel valves & reg/rect from Oregon MC Parts. Raptor CCT, XJ air shocks, 850 FD, Sportster mufflers, Standard handle bar, Tusk Bar Risers, SS braided brake lines. Cat Eye speedometer. HID projector beam headlight, LED running lights.

              Comment

              • #8
                My XJ is running a 78 lower end, 79 cylinders, XJ head, cams, and carbs. works very well so far.
                K. Johnson
                -1978 XS750SF - brought back from the dead with carb
                triple clean and boots
                -1982 XJ1100J - brought back from the dead by
                replacing motor after throwing #4 rod
                -1985 XJ750XN - shim job, oil change, ride. not bad for
                $500 including new rear tire.

                Comment

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