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    Strange Valve Shim Adjustment

    I did a valve adjustment today and it mostly went fine but the exhaust for cylinder 1 is being strange so I wanted to run this by someone else for some ideas.

    I started with a 2.7 shim in the tappet and could only get a .03mm feeler in there. I dropped it down to a 2.65 shim and then it jumped to a .10mm feeler. Is it just me or does that math not add up? I did check both shims with a digital caliber multiple times and they were true to size.

    I did take a ride with the 2.65 shim and it made the cylinder 1 exhaust pipe really hot so I'm gonna be going back to the 2.7. I would like to get a little more clearance for that valve but I'm not sure what to do. Is it possible to get in between shims? Like a 2.68? Also what would cause that? A bad lobe, bent cam?

    #2
    Are you sure you checked the clearances with the cams in the correct / exact same positions?
    Current:
    Z1300A5 Locomotive (swapped my Intruder for it), GS450 Cafe Project (might never finish it....), XT500 Commuter (I know - it's a Yamaha )

    Past:
    VL1500 Intruder (swapped for Z1300), ZX9R Streetfighter (lets face it - too fast....), 1984 GSX750EF, 1984 GSX1100EF (AKA GS1150)
    And a bunch of other crap Yamahas....

    Comment


      #3
      A shim with an X on it is in between sizes. 2.65X for instance is what you need. Did you by chance use a zip tie or the motion pro tappett depresser? With the zip tie, there's a possibility of dislodging some soot inside the head giving a false reading if the soot prevents the valve from seating. However, since you ran it for a bit, any soot would probably have been blown out. Just sharing my thoughts for what it's worth.

      Heres a pic of the shim.

      Roger

      Current rides
      1983 GS 850G
      2003 FJR 1300A
      Gone but not forgotten 1985 Rebel 250, 1991 XT225, 2004 KLR650, 1981 GS850G, 1982 GS1100GL, 2002 DL1000, 2005 KLR650, 2003 KLX400

      Comment


        #4
        Don't worry about the "extra" clearance. Many of us will go up to 0.10mm. The extra clearance keeps the valve on the seat just a little bit longer, letting it run cooler. It also reduces lift, duration and overlap, making it run a bit better at lower engine speeds, where some of us spend most of our time. Not everybody hits redline at every shift.

        .
        sigpic
        mine: 2000 Honda GoldWing GL1500SE and 1980 GS850G'K' "Junior"
        hers: 1982 GS850GL - "Angel" and 1969 Suzuki T250 Scrambler
        #1 son: 1986 Yamaha Venture Royale 1300 and 1982 GS650GL "Rat Bagger"
        #2 son: 1980 GS1000G
        Family Portrait
        Siblings and Spouses
        Mom's first ride
        Want a copy of my valve adjust spreadsheet for your 2-valve per cylinder engine? Send me an e-mail request (not a PM)
        (Click on my username in the upper-left corner for e-mail info.)

        Comment


          #5
          Originally posted by hillsy View Post
          Are you sure you checked the clearances with the cams in the correct / exact same positions?
          Yes, I checked the clearances according to the manual with the lobe pointing up (position A in the diagram below). I also checked multiple times and cranked the engine a full rotation after swapping shims so they would be depressed and properly seated.

          Comment


            #6
            Originally posted by Burque73 View Post
            A shim with an X on it is in between sizes. 2.65X for instance is what you need. Did you by chance use a zip tie or the motion pro tappett depresser? With the zip tie, there's a possibility of dislodging some soot inside the head giving a false reading if the soot prevents the valve from seating. However, since you ran it for a bit, any soot would probably have been blown out. Just sharing my thoughts for what it's worth.
            That's good to know the X is in-between. I've got 3 cylinder heads worth of shims so I'll have to double check if I have one like that. I used the motion pro tool. And thanks for your thoughts. That's why I made the post.

            Comment


              #7
              Originally posted by Steve View Post
              Don't worry about the "extra" clearance. Many of us will go up to 0.10mm. The extra clearance keeps the valve on the seat just a little bit longer, letting it run cooler. It also reduces lift, duration and overlap, making it run a bit better at lower engine speeds, where some of us spend most of our time. Not everybody hits redline at every shift. .
              I've seen that some people run with .10mm which is why I left it in and went for a ride but my exhaust pipe was really getting hot. I just installed a 4-1 mac system that came in a black semi glossy finish and just after a short 5 min ride it changed pipe 1 to matte black. The extra heat is what I'm really worried about.

              Comment


                #8
                Those valve clearances either way should not have any notable effect on the exhaust temp - I'd say you have a lean condition from some other source.
                Current:
                Z1300A5 Locomotive (swapped my Intruder for it), GS450 Cafe Project (might never finish it....), XT500 Commuter (I know - it's a Yamaha )

                Past:
                VL1500 Intruder (swapped for Z1300), ZX9R Streetfighter (lets face it - too fast....), 1984 GSX750EF, 1984 GSX1100EF (AKA GS1150)
                And a bunch of other crap Yamahas....

                Comment


                  #9
                  Originally posted by Steve View Post
                  Don't worry about the "extra" clearance. Many of us will go up to 0.10mm. The extra clearance keeps the valve on the seat just a little bit longer, letting it run cooler. It also reduces lift, duration and overlap, making it run a bit better at lower engine speeds, where some of us spend most of our time. Not everybody hits redline at every shift.

                  .
                  WHAT??? You're joking, right?
                  sigpic
                  09 Kaw C14 Rocket powered Barcalounger
                  1983 GS1100e
                  82\83 1100e Frankenbike
                  1980 GS1260
                  Previous 65 Suzuki 80 Scrambler, 76 KZ900, 02 GSF1200S, 81 GS1100e, 80 GS850G

                  Comment


                    #10
                    Nope, not joking. I only hit redline every OTHER shift.

                    .
                    sigpic
                    mine: 2000 Honda GoldWing GL1500SE and 1980 GS850G'K' "Junior"
                    hers: 1982 GS850GL - "Angel" and 1969 Suzuki T250 Scrambler
                    #1 son: 1986 Yamaha Venture Royale 1300 and 1982 GS650GL "Rat Bagger"
                    #2 son: 1980 GS1000G
                    Family Portrait
                    Siblings and Spouses
                    Mom's first ride
                    Want a copy of my valve adjust spreadsheet for your 2-valve per cylinder engine? Send me an e-mail request (not a PM)
                    (Click on my username in the upper-left corner for e-mail info.)

                    Comment


                      #11
                      Originally posted by hillsy View Post
                      Those valve clearances either way should not have any notable effect on the exhaust temp - I'd say you have a lean condition from some other source.
                      Yeah, that didn't seem right to me either. Good to hear that from someone else. This bike also has an issue with no top end acceleration. I suspect this is all connected and based on some reading I've been doing I think the main jet is undersized.

                      Comment


                        #12
                        I swapped the shim back to the 2.70 that was in there before and the exhaust is running cooler again. I'm still surprised how such a slight change made that cylinder run so lean that the pipe changed color in no time. But it did make me pull the trigger on buying larger main jets. The bike just feels starved through all gears but I haven't been able to find a good place to do a full throttle plug chop to verify my suspicion.

                        At this point, I'm just going off all the CV carbs tuning articles that say to start the process
                        by finding amain jet that produces the hardest pull at high rpm.
                        Last edited by Guest; 06-07-2017, 09:53 AM.

                        Comment


                          #13
                          I would describe your jetting, air intake, exhaust etc and let some of the gurus here suggest a likely jetting and needle shimming (or not shimming) so you don't have to buy a bunch of different main jets to experiment with. I admit I'm kind of cheap. Also, most of the gurus here may work more with larger displacements.
                          1983 GS 1100 Guided Laser
                          1983 GS 1100 G
                          2000 Suzuki Intruder 1500, "Piggy Sue"
                          2000 GSF 1200 Bandit (totaled in deer strike)
                          1986 Suzuki Cavalcade GV 1400 LX (SOLD)

                          I find working on my motorcycle mildly therapeutic when I'm not cursing.

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