Should throttle 'snap' back when let go?
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Thread: Should throttle 'snap' back when let go?

  1. #1
    Junior Member Ecosta777's Avatar
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    Should throttle 'snap' back when let go?

    I have a 1978 CB400A I am rebuilding, I just got done with the carb rebuild and I installed it along with new throttle cables. The old ones were frozen so I don't know how the throttle is supposed to 'act' on this bike.

    On my old BSA lighting, when I let go of the throttle, it snaps back to its original position, and goes back to idle.

    I am not ready to fire the CB400A yet, but I was playing with the throttle after I installed everything. This one seems to stick in place. When I let go it won't snap back to its original position. I cleaned up the twist grip a little thinking that was the problem, but nothing changed. Should this type of throttle snap back? My BSA throttle has a tensioner on it, so I could set it to stay in place if I chose, but I don't see anything like that on the Honda

    I assumed all throttles just snapped back, or had tension adjustments - the Honda is only my second bike so I just want to be sure. I prefer it to let go when I let go. Do I Just need to clean it up more and lube it?

    This bike has a Keihin VB24A carb if that makes any difference.

    Thanks
    Eric

  2. #2
    Supporting Member krukster86's Avatar
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    Not familiar with your model, but it should snap back. Is there a hang up at the carburetor spring area, or is it in the cable routing itself? Sometimes if the cable routing is too constricted, it binds up and freezes in place.
    1975 CB360T Cafe Project (Being rebuilt from crispy bits!) - Done-ish...now in maintenance mode
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  3. #3
    Senior Member 80cb400t's Avatar
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    I think the A models are the same as the other 400s, it should definitely snap back and it's probably due to adjustment. There's adjustment at the carbs and there's an adjustment on the handlebars. The service manual should help with which direction to turn them. I recall turning the handlebar adjuster clockwise (or so less threads show) making it looser (allows it the slack to snap back). Try all the way in and see if it snaps back, if not you might need to adjust at the carbs. Also make sure it still snaps back with the bars fully turned in both directions.
    1980 CB400T - 1 running, 1 parts bike
    1965 CB160 - 1 kind of running, 1 parts bike

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  5. #4
    Senior Member 83XLX's Avatar
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    Make sure your throttle isn't slid onto the handlebar too far. If the inside of the rubber hand grip is tight against the end of the handlebar, it will want to hang open and not snap back.
    1969 Honda CL350
    1983 H-D XLX-61 Sportster

  6. #5
    Junior Member Michjsear's Avatar
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    If cable adjustment doesn’t help, remove the cables from the throttle tube/grip and see if it moves freely. If there is any debris inside the throttle tube or oxidation on the handlebars, it will hang up.

  7. #6
    Senior Member Rob Axel's Avatar
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    What? You mean this model come standard with "cruise contrrol"??
    "Yes, my hands and nails have grease stains. I ride vintage!"
    -xulf13-

  8. #7
    Junior Member Kevinx's Avatar
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    I would suggest you change the cables unless you want to practice jumping off the bike when the throttle jams at high speed . Every throttle needs to return to idle after you let go.

  9. #8
    Super Moderator ancientdad's Avatar
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    Quote Originally Posted by Kevinx View Post
    I would suggest you change the cables unless you want to practice jumping off the bike when the throttle jams at high speed . Every throttle needs to return to idle after you let go.
    In case you don't realize, his bike has push-pull throttle cables that can be rotated back to idle forcibly if necessary... plus the usual kill switch and ignition switch as well, so bailing isn't likely necessary. But it sounded dramatic.
    Klaus likes this.
    Tom

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  10. #9
    Senior Member Bill H's Avatar
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    I dont know how you ran your cables but I found on my A that if you remove the left top motor mount and run the cables between the top mounts they work a lot better. Going around the left mount puts them in a bind. Having worked on several As I KNOW its a lot of work but I would pull the carbs back off , put all the cables on and see how they work ,if ok I would reinstall the carbs with the cables in between the upper mounts.

    Hope this helps.

    Bill

  11. #10
    Senior Member mike in idaho's Avatar
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    There needs to be a little bit of slack in the cables(1 mm or so) if they're pulling against each other things will bind.
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