CT70 won't shift when running

Discussion in 'General' started by John Stamos, Jun 2, 2020.

  1. John Stamos

    John Stamos New Member

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    Hello,

    I'm having an issue with my CT70 and I can't seem to figure out what's going on. The bike shifts totally fine when it's not running. I can manually spin the fly wheel by hand and shift between all gears fine. However when the bike is running, as soon as as I touch the shift lever, I just hear grinding and it won't do anything.

    Does anyone have any insight? I've taken apart the clutch cover and everything appears to be in place for the mechanism to disengage the clutch when you shift.

    Thanks!
     
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  3. kirrbby

    kirrbby Well-Known Member

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    If your bike is idling too fast, that will cause your centrifugal clutch to be engaged, and not allow you to shift. If the clutch pack is sticking, rusted, improperly assembled, etc, it may not be disengaging to allow you to shift. Kinda like trying to put your old truck in gear without depressing the clutch pedal.
     
  4. racerx

    racerx Administrator
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    Best educated guess, your clutch preload adjustment is way off, or the clutch isn't disengaging.

    The clutch should still disengage at idle, if everything is correctly assembled, the clutchpack isn't locked-up and idle speed is close to spec. You didn't say if the cltuch has been removed from the crank, so I'll leave the assembly issue alone, for now.

    Learn how to set the clutch preload. Lay the bike over onto the flywheel side, to prevent a major oil spill. Then loosen the clutch cover screws. Loosen the clutch adjuster locknut, then turn the preload adjusting screw until you feel contact, then until the cover begins moving away from the crankcase. That should teach you to recognize the contact point. After this, retorque the clutch cover screws, readjust the preload screw until you feel it making contact, then back it off 1/8-1/4 turn. That should have the preload dialed-in. If that makes no difference, we can go into possible clutch assembly issues.
     
  5. John Stamos

    John Stamos New Member

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    Correct. The clutch has not been removed. The only thing I have done is taken off the clutch cover and had a look at the clutch cam assembly.

    Can you possibly explain how that "clutch cam" assembly thing even works? I don't understand how that is supposed to disengage the clutch when shifting? Because realistically, even if the clutch is engaged, shouldn't this piece still force the clutch to disengage once I try to shift? I have tried playing with the adjusting screw but I don't understand how it even does anything.

    Sorry about my vague understanding... i've never worked on a clutch like this.
     
  6. racerx

    racerx Administrator
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    No worries, we all started out where you are right now.

    You are correct, this is a semi-automatic clutch. At low rpm, the centrifugal mechanism disengages. When you move the shifter, in either direction, that cam assembly disengages the clutch same as a hand lever would, if it were a full manual. Holding the shifter, at either extreme, will disengage the clutch...if everything is assembled, adjusted and working correctly.

    There's one issue that cannot be ignored. The clutch release doesn't engage until the shifter is fully depressed/lifted. That means going from neutral-to-first gear, the centrifugal mechanism must operate or the bike will either lurch, grunch into gear and then stall or all three. If the shift lever is full depressed, the engine should not turn over via the kickstarter. Trust me, that's a tough maneuver for one person to execute.

    Adjusting the clutch preload moves the base cam plate, changing when the clutch is released. Tighter/narrower preload brings the release earlier into the cycle, opening it up delays it. Go too tight and the clutch will slip, too loose it'll never disengage and you'll be effectively running clutchless.
     
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  7. kirrbby

    kirrbby Well-Known Member

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    Well...
    It could take a while to give a good, thorough, explanation.
    Let's just say, yes. The shifter should disengage the clutch. But, it relies on that preload adjustment to be able to work. If it's way off...too loose, the shifter can't disengage the clutch.
    Maybe try this...
    IMG_20200515_151520895.jpg
     
  8. Tripod

    Tripod Active Member

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    Make sure you put the cover on right with the right orientation of the clutch cam.
     
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  9. racerx

    racerx Administrator
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    And also be sure that the actuator arm is clocked correctly. One spline off and it'll never shift right.
     
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  10. cjpayne

    cjpayne Well-Known Member

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    racerx likes this.

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