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shutting off automotive engine cylinders

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  • shutting off automotive engine cylinders

    when they say a modern engines can shut off cylinders to save fuel, what happens? and does it make the engine wear funny?

    when i run on less than four on the xs11 it's not really running,

    thinkin of pickin up an 09 camaro 400 horses and 30 mpg
    "a good man knows his limitations" dirty harry
    History
    85 Yamaha FJ 1100
    79 yamaha xs1100f
    03 honda cbr 600 f4
    91 yamaha fzr 600
    84 yamaha fj 1100
    82 yamaha seca 750
    87 yamaha fazer
    86 yamaha maxim x
    82 yamaha vision
    78 yamaha rd 400

  • #2
    As I understand it, it shuts off the fuel and the spark to the cylinders it doesn't want to run. the rest is the same. Don't hold me to it but that's how I heard they work. the oil still lubricated everything, they just don't fire. I believe the lack of spark and fuel makes the engine run like the dead cylinders are not there. That's my story and I'm sticking to it.....at least till someone has a better explanation as to how they work. have a nice day and ride safe.
    I am the Lorax, I speak for the Trees

    '80 XS1100 SG (It's Evil, Wicked, Mean & Nasty)

    '79 XS1100 F R (IL Barrachino)

    '00 Suzuki Intruder 1400 (La Soccola)

    '77 KZ400s (La Putana)

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    • #3
      sorta

      Sorta but a valve would also have to be open so there is no compression or else the purpose would be defeated. Dontca think ?
      Doug
      Doug Mitchell
      82 XJ1100 sold
      2006 Suzuki C90 SE 1500 CC Cruiser sold
      2007 Stratoliner 1900 sold
      1999 Honda Valkyrie interstate
      47 years riding and still learning, does that make me a slow learner?

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      • #4
        Quite possible, but I believe it would be a whole lot more difficult to disable valves than fuel and spark. but then again, honda does something like that on those V-Tech engines...supposed to be an 8 valve motor at low rpm (better Torque), and a 16 valve at higher RPM (Breathes better). I don't understand how exactly that one works either. have a nice day and ride safe.
        I am the Lorax, I speak for the Trees

        '80 XS1100 SG (It's Evil, Wicked, Mean & Nasty)

        '79 XS1100 F R (IL Barrachino)

        '00 Suzuki Intruder 1400 (La Soccola)

        '77 KZ400s (La Putana)

        Comment


        • #5
          Really wouldn't be that difficult, Lorax.
          Some big single cylinder bikes have compression relief levers. It just pulls on a gizmo by the cam, a lever comes down and holds the exhaust valve open a little on the compression stroke.
          Bike starts with less effort on your "kicking leg".
          Just need a gizmo to hold the exhaust valve open and an extra throttle plate type thing to block the air/fuel from entering the cylinder.
          Cadillac did something like this twenty years ago. Car ran on eight cylinders... then once at highway speed, would shut down two of them to save on fuel. I'm not familiar with what system they used for that. It may have alternated cylinders to even out vibration
          "Damn it Jim, I'm a doctor, not a mechanic!' ('Bones' McCoy)

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          • #6
            Stops

            valves from working. No intake = no compression, no exhaust needed. Down stroke = little vacuum and upstroke = little compression. Of course no fuel injected. Cadillac has been doing that for years....
            You can't stay young forever, but you can be immature for the rest of your life...

            '78E "Pathfinder" Show bike...
            Lovingly restored by Dave Delzell
            Drilled airbox
            Tkat fork brace
            Hardly mufflers
            late model carbs
            Newer style fuses
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            • #7
              Cylinder shut off

              The valves are closed so that the affected cylinder does not act as an air pump. That would send unburned oxygen to the O2 sensors which would then richen the mixture. The injectors are shut off but the spark plug continues to fire.
              On some of the cars, the cylinders are activated after a certain number of "dead" revelutions to help keep the cylinder temperature in the active range.
              Walt
              80 XS11s - "Landshark"
              79 XS11s
              03 Valkyrie
              80 XS Midnight Special - Freebee 1
              78 Honda CB125C - Freebee 2
              81 Suzuki 850L - Freebee 3

              Comment


              • #8
                Well, you really do learn something new every day. Prom, now that you mention it, when I was but a whelp, I had a moped, if my memory serves me correctly, it had a cable operated compression release on it. thanks for the reminder. neat - o - keen technology...multiple displacement engines. what will they think of next?
                I am the Lorax, I speak for the Trees

                '80 XS1100 SG (It's Evil, Wicked, Mean & Nasty)

                '79 XS1100 F R (IL Barrachino)

                '00 Suzuki Intruder 1400 (La Soccola)

                '77 KZ400s (La Putana)

                Comment


                • #9
                  old trick new dog.

                  GM tried this before back in the 80s,with their higher end cars, they dropped anywhere from 2 to 4 cylinders using sensors connected to the main computer, but they had trouble with them cutting in and out at odd times, like while trying to pass another car. With the improvements in computers now it sounds more probable now. Someone even come up with a computer that makes GM's crossfire injection work the way it was intended,but wouldn't because at the time they didn't have the computer technology to make it work. I think Prom was right it worked by using a controlled valve system to decompress the cylinders, and now with todays computers controlling every thing in the car,right down to the seat adjustment, it wouldn't be hard to drop a few cylinders on demand.
                  Fastmover
                  "Just plant us in the damn garden with the stupid
                  lion". SHL
                  78 XS1100e

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                  • #10
                    OMG!!

                    LOL.. I was just thinking about this same thing yesterday! I was wondering about what would happen if you got to highway speed on a long haul, and closed one of the petcocks... shutting off either the right two or left two cylinders. Cruising at 4-5k, I was wondering if it would save or take more fuel because those 2 would be working harder... no worries about O2 sensors on these.

                    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

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                    • #11
                      Actually, most if not all cylinder deactivation systems don't hold valves open. It takes energy to compress the air, but most of that energy is returned on the down stroke. Modern systems also alternate which cylinders are deactivated, swapping banks on a V-8 for example.
                      2010 Kawasaki Z1000
                      1979 SF: Millennium Falcon, until this Saturday

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