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80 head, 81 head, valve train compatability

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  • 80 head, 81 head, valve train compatability

    I have an 80 head and an 81 head, I need to make one working head out of the two. I have and 81 xs 1100 special. I have a very large hole burnt through the #3 exhaust valve. I do not have the the cam caps for the 80 head (the guy on ebay that sold me the head swears the caps stay with the cam and by the time my machinist said he was wrong, the PO sold the cam and cam caps). I noticed the 80 valves are smaller and am wondering can they be used in my 81 head or can my 81 cam caps somehow be machined to fit the 80 head?

  • #2
    Then you got rooked in more ways than one, cause 80 and 81 valves are the same. If the valves are smaller they are 79 or earlier valves, and you can't switch them. AFAIK the heads on the 80 and 81 are exactly the same, same part number and all. Geezer on here has a deal for brand new SS valves for both the early and late heads, but I'm not sure if he has any left over from the last order of them or not, and I'm not sure when he will be doing another run of them. He has them custom made through a company that makes stuff like that.
    Cy

    1980 XS1100G (Brutus) w/81H Engine
    Duplicolor Mirage Paint Job (Purple/Green)
    Vetter Windjammer IV
    Vetter hard bags & Trunk
    OEM Luggage Rack
    Jardine Spaghetti 4-2 exhaust system
    Spade Fuse Box
    Turn Signal Auto Cancel Mod
    750 FD Mod
    TC Spin on Oil Filter Adapter (temp removed)
    XJ1100 Front Footpegs
    XJ1100 Shocks

    I was always taught to respect my elders, but it keeps getting harder to find one.

    Comment


    • #3
      as cy already stated,
      if the valves are smaller then its from an earlier
      model engine.


      while ur waiting on getting another valve
      u might also want to establish why the valve burnt in
      the first place so it wont go happening again when
      the valve is replaced.

      a couple of things that can cause this
      worn valve guides - can prevent the valve from seating properly,
      overheating the enging,
      lean running mixture,
      pre-ignition and detonation.

      i burnt one of mine after a cpl of thousand k's
      after i lapped the valves, the thickness of the valve was
      to thin, heres a pic of that valve.



      minimum thickness should be 1mm.

      while u have the head off, pour fuel into the ports and
      check the valves for seapage.

      hope this helps u.
      pete


      new owner of
      08 gen2 hayabusa


      former owner
      1981 xs1100 RH (aus) (5N5)
      zrx carbs
      18mm float height
      145 main jets
      38 pilots
      slide needle shimmed .5mm washer
      fitted with v/stax and uni pod filters

      [url]http://www.youtube.com/watch?v=3pA8dwxmAVA&feature=mfu_in_order&list=UL[/url]

      Comment


      • #4
        Yep, from the factory the 80 and 81 heads would be identical. Exhaust valves on all should be identical no matter what year, but the intakes valves got a little bigger on the 80-81 models. If your head has smaller valves, it may well be a 79 engine instead of an 80. Check the VIN on the engine itself.

        As to the cam caps, since they do not have bearings in them, I'd be very leary of mixing and matching them with worn in cams and heads. You can switch the valves easy enough, but if possible I'd keep the cams and the caps on the head they were with originally. Now, if that causes you problems and makes something not work, well, then I would take my chances and mix and match to get one working. Just not my first choice.
        Life is what happens while your planning everything else!

        When your work speaks for itself, don't interrupt.

        81 XS1100 Special - Humpty Dumpty
        80 XS1100 Special - Project Resurrection


        Previously owned
        93 GSX600F
        80 XS1100 Special - Ruby
        81 XS1100 Special
        81 CB750 C
        80 CB750 C
        78 XS750

        Comment


        • #5
          +1, keep the caps with the head it goes to if possible. You can buy late model (80-82) valves from these guys for about $20 if need be....

          http://www.crc2onlinecatalog.com/Index_Main_Frame.htm
          2H7 (79) owned since '89
          3H3 owned since '06

          "If it ain't broke, modify it"

          ☮

          Comment


          • #6
            You sir, are amazing, for the next twenty four hours you are my hero! I can get the one valve I need and get my bike back together again. Thank you!

            Comment


            • #7
              I would suggest that if your pulling the head off, and the engine has enough wear to have that valve issue, you probably want to replace the cam chain while your in there. And perhaps valve seals, and lap the valves. Funny how the "might-as-wells" add up.
              Life is what happens while your planning everything else!

              When your work speaks for itself, don't interrupt.

              81 XS1100 Special - Humpty Dumpty
              80 XS1100 Special - Project Resurrection


              Previously owned
              93 GSX600F
              80 XS1100 Special - Ruby
              81 XS1100 Special
              81 CB750 C
              80 CB750 C
              78 XS750

              Comment


              • #8
                Originally posted by yamahaluke View Post
                I can get the one valve I need and get my bike back together again. Thank you!
                Yep, just make sure there is no damage to the seat area on the head. You can check for leaks as follows.

                After installing the new valve, place the head on the workbench upside down with the spark plugs in, making sure it is level. Pour gasoline up to the top of each combustion chamber. Wait 15 minutes and see if any of the levels have gone down. If not, there are no leaks and you can install the head with a new head gasket. Do not apply any sealer. HTH, good luck!

                Edit: It's a good idea to scrape off any excess carbon, but be careful not to gouge the aluminum while doing. New valve seals would be a good idea also.
                Last edited by bikerphil; 01-14-2011, 12:18 PM.
                2H7 (79) owned since '89
                3H3 owned since '06

                "If it ain't broke, modify it"

                ☮

                Comment


                • #9
                  "After installing the new valve, place the head on the workbench upside down with the spark plugs in, making sure it is level. Pour gasoline up to the top of each combustion chamber. Wait 15 minutes and see if any of the levels have gone down. If not, there are no leaks and you can install the head with a new head gasket. Do not apply any sealer. HTH, good luck!"

                  works either way,
                  i just find it easier if u pour fuel straight into the ports (head tilted on the side)
                  ull notice straight away if fuel is seaping/leaking between the valve and seat
                  from the combustion chamber.

                  he'l also need to lap any new valve thats put in.
                  pete


                  new owner of
                  08 gen2 hayabusa


                  former owner
                  1981 xs1100 RH (aus) (5N5)
                  zrx carbs
                  18mm float height
                  145 main jets
                  38 pilots
                  slide needle shimmed .5mm washer
                  fitted with v/stax and uni pod filters

                  [url]http://www.youtube.com/watch?v=3pA8dwxmAVA&feature=mfu_in_order&list=UL[/url]

                  Comment


                  • #10
                    Originally posted by petejw View Post
                    he'l also need to lap any new valve thats put in.
                    Yep, that's probably a good idea. When I replaced my bent exhaust valve a few years back, I didn't lap it. I must've got lucky, it runs just fine.
                    2H7 (79) owned since '89
                    3H3 owned since '06

                    "If it ain't broke, modify it"

                    ☮

                    Comment


                    • #11
                      Originally posted by petejw View Post
                      i just find it easier if u pour fuel straight into the ports (head tilted on the side)
                      ull notice straight away if fuel is seeping/leaking between the valve and seat
                      from the combustion chamber.
                      You would probably want to do this somewhere outside rather than inside your basement or workshop...
                      Ken Talbot

                      Comment


                      • #12
                        If you end up mix-matching the caps you could always get some plastigauge and check your clearances. IDK what the spec is but you would be able to compare each one and pick the most reasonable one if you have a few to choose from... I would expect them all to be pretty close...
                        '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


                        • #13
                          The cams are different between the later and earlier xs11s also I think... Personally, I wouldnt buy a head without the cams attached.
                          Skids (Sid Hansen)

                          Down to one 1978 E. Stock air box with K&N filter, 81H pipes and carbs, 8500 feet elevation.

                          Comment


                          • #14
                            hi skids,
                            the cams themselves are interchangable between
                            different model heads,
                            the cam caps and the head are milled together
                            and shouldnt be interchanged,
                            ive heard of others that have used different caps on different heads
                            with out any problems but its not reccomended.
                            pete


                            new owner of
                            08 gen2 hayabusa


                            former owner
                            1981 xs1100 RH (aus) (5N5)
                            zrx carbs
                            18mm float height
                            145 main jets
                            38 pilots
                            slide needle shimmed .5mm washer
                            fitted with v/stax and uni pod filters

                            [url]http://www.youtube.com/watch?v=3pA8dwxmAVA&feature=mfu_in_order&list=UL[/url]

                            Comment


                            • #15
                              Now this is a bit far out there and most likely not worth it (until parts get more scarce) BUT would it be possible to have the head and caps milled down and then insert a bearing in there in place of just the factory surface?
                              Nathan
                              KD9ARL

                              μολὼν λαβέ

                              1978 XS1100E
                              K&N Filter
                              #45 pilot Jet, #137.5 Main Jet
                              OEM Exhaust
                              ATK Fork Brace
                              LED Dash lights
                              Ammeter, Oil Pressure, Oil Temp, and Volt Meters

                              Green Monster Coils
                              SS Brake Lines
                              Vision 550 Auto Tensioner

                              In any moment of decision the best thing you can do is the right thing, the next best thing is the wrong thing, and the worst thing you can do is nothing.

                              Theodore Roosevelt

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