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Throttle keeps getting loose

Discussion in 'Maintenance and Servicing' started by RedWings01, Aug 20, 2016.

  1. Hey guys,

    Had throttle cables replaced about a month ago by the mechanic. He did a really lousy job and didn't tighten any of the lock nuts. I tightened them when I got my bike back. Something i noticed is that my throttle free play keeps increasing. I've had to tighten it 2 times already. I looked on the carby side and one of the throttle cables are bent slightly. If I took the cable out, it would bend slightly and not be straight. Is that normal? I assume it is from being pulled around every time I open the throttle. Is there any reason why I need to keep adjusting the play? Last throttle cable I only ever adjusted once in a few months. It barely went out of spec. Could it be because it isn't lubed?

  2. Two thoughts. Is the lock nut done up against the correct end of the thread?

    And have you checked the other end of the cable? It could be loose at that end.
  3. Thanks for your reply. They were a tad loose. Not loose enough to be able to turn with my finger but just snugged them up the best I could with the space I have.
  4. Check that the ferrules on the cable ends are properly seated, check that there aren't kinks in the inner at the ends where the nipples are, and as noted by ibast, check you've nipped up the locknuts after adjustment.
    A little bit of stretch/settling is normal, but not repeatedly.
  5. There is a slight bend on the top cable. Do I need to worry about this?

    Note I pulled the throttle to take away the free play to show it better.

    Attached Files:

  6. I think you are missing a nut on that top throttle.
    • Agree Agree x 1
  7. Would be causing a little more freeplay than necessary, so slacken the cable, remove the nipple and simply bend and straighten the kink with your fingers.
    • Agree Agree x 1
  8. Yep, that's the sort of kink I was talking about, it allows flex and added freeplay once it's under tension.
    Get rid of the kink and then adjust the freeplay.
  9. when I read the title I thought the throttle was getting loose because you were fully workin' it - braaaaaaappppppp
  10. Ok guys, I was trying to loosen the top wire to bend it straight again. I just realised that it is the return wire and was thinking that shouldn't really affect the free play? I loosened locknut on the right hand side of the top wire and started to turn the adjuster. I turned one way, turned the other way, nothing. It did not get loose or tight. The only thing that happened was that it could pop out of the little clip holding it in. Wtf? I decided to have a go at the bottom throttle wire and that one also does the same. No matter which way i turn the adjuster, it will not tighten or go loose. It only pops itself out of the clip. What is going on here? The only place where I can actually do something is on the handlebar side. I can turn the adjuster and it tightens the throttle cable. What am I doing wrong? All the tutorials I have seen on google and youtube are to do with handlebar. I haven't seen anyone do it on the throttle side. Am I stupid? What am I missing out here? Which way am I supposed to turn the adjuster and how exactly do I do it? Sorry if this sounds stupid.

  11. No, it's getting loose because he's getting kinky with it ;-)
    • Funny Funny x 1
  12. Undo the top locknut (as per your picture)
    Screw the top barrel adjuster out of the bracket/clamp so some thread show on the left side of the bracket/clamp.
    Do this to take the slack out and have both open and closing cables under a tiny bit of tension.
    Tighten the top locknut
    Make any fine adjustments to get correct free play at the twist grip end.
  13. #13 RedWings01, Aug 20, 2016
    Last edited: Aug 20, 2016
    Right, just tried exactly what you said. Undid the locknut, gave the adjuster a solid 10-15 rotations away from the clamp and nope nothing. I have no clue what is going on anymore. Tried to do it on the bottom cable too, undid the locknut, turned adjuster away from clamp, does nothing. Great. Either its not working, or im just stupid.

    What I do exactly is, on the top right locknut, I turn that downward while holding the adjuster still. After the locknut is loose, I use my finger and turn the adjuster upwards. After about 15 turns, nothing happens. What am I doing wrong?
  14. So the adjuster doesn't unscrew out of the bracket and expose threads on that side?
    Sounds like the adjuster is screwed too far through the bracket.
    Take the tension off the cables (perhaps at the twist grip end)
    Loosen the locknut well off and pull the adjuster barrel back toward the cable outer side and unscrew it with the aim of getting the threads started back into the bracket.
    Once the barrel adjuster is moving back and forth in the bracket as you turn it each way, then you can set the cable with a tiny bit of tension and lock the locknuts
    Then adjust free play at the twist grip end.

    See if you can find a workshop manual as a PDF download for yours or a similar model
    It should explain the right order and measurements for settin up the cables and free play.
  15. Seems the adjuster you are referring to at the top left is just a spacer, turning it does nothing. I think ibastibast is on the money and you have a nut missing. The nuts determine the slack/freeplay, not those wide nut type things which are only spacers. Having said that, I could be wrong.
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  16. #16 Harb, Aug 20, 2016
    Last edited: Aug 20, 2016
    You adjust the freeplay by adjusting both nuts on the bottom to give you a small amount of slack at closed throttle (this is the throttle cable) - 2-6mm at the flange on the grip according to the manual, I personally set mine up so that there is 0 free play on right lock and whatever the remainder is on the left lock to make sure throttle is never being rotated during steering.

    Then do the top so that there is minimal free play at the carby with a strong return action (return cable). There is only meant to be a single nut on the top, you rotate this nut to adjust. NedNed is spot on, the left side of both cables are just spacers, no adjustment available. Throttles are a pain, but come back to it with a fresh mind and it'll come more naturally ;)

    Edit: see pic from manual
    • Like Like x 3
  17. #17 jstava, Aug 20, 2016
    Last edited: Aug 20, 2016
    RedWings01RedWings01 there might be a problem in what you are expecting to happen when you turn the nuts in the top cable

    ibastibast suggested you might be missing a nut on the top cable. I agree with him, at least a second nut would make your adjustment possible. Many cables terminate in a fitting which includes threads - only one nut is required in such cases. In your case, the clamp holding the cable (retained by the phillips head screw) appears not to be threaded. a nut on either side of this clamp would be in order to positively locate your cable end and make it possible to adjust the amount of slack

    The clamps simply hold the hollow threaded shaft housing the cable in place against the carby. You need to turn both nuts in turn to move the threaded portion left or right. this is the way it is with the bottom cable, but this cannot happen with the top cable as there is no opposing nut to pinch the threaded portion in its final position. Normally, you would loosen the right hand nut and tighten the left hand one to move the cable end to the left, which is what I'm assuming is what you want to do.

    Instead, when you loosen the nut, the threaded part can move to the left to tighten the cable but there is nothing to hold it in that position (no nut and the fitting holding the cable to the carburettor is not threaded) Never mind, all is not lost. You will never fit a nut over the cable end to add one, so do the next best thing, Undo the phillips screw and move the nut to the other side, (the left side) You will now have an arrangement which will ensure that the top cable can be tensioned. Your actual adjustment of the actuation of the throttle then lies entirely with the bottom set of nuts. Your actual throttle free play should be set at the handlebar end. Do this last, after confirming that the adjustment you have made at the carburettor end allows your carburettor to fully open and close.

    I hope this helps. This is a generic response. You MAY not have free play adjustment at the handlebars. If this is the case, you will never take it up for real without moving the single nut from the right to the left hand side of that retainer clamp. In which case your free play adjustment is all in what you see, and it is in the small, but important amount of slack that you want to control in the top cable. NB. There needs to be some slack. If your cables oppose each other by being in constant tension, your throttle will bind and not return by itself.

    There still might be a problem with this arrangement - no opposing nut means that there is no pinch of the clamp which secures the cable end to the carby. Motorcycles vibrate, and the nut may rotate on its own. a little locktite on the threads once you know its in the right position will keep it from moving.

    Disclaimer: I am not a mechanic - ideas only, not expert advice. I don't even know what bike this is. Consider it however you wish.
    • Like Like x 1
  18. Thanks so much for your help guys. I think I understand what you mean. I did some digging around online and like you said, the top cable cannot be adjusted. Apparently the top cable is there for emergency to close the throttle if the spring or something fails and you can remove it and the throttle should still snap close. This lead me to believe that I cannot adjust the top. Following your instructions, I was able to move the adjuster at the handlebar into the middle, lock it off, go to the carb and tighten the cable there.

    I have uploaded a picture of the result. If you compare to the earlier picture, i was able to tighten it. Like you guys said, you need the two nuts to be able to do this. I don't think I am missing the nut on the top as other pictures show that there is only one nut and that the return cable is not even meant to be tightened as it is for emergency only. Hopefully I have done this correctly on the bottom adjuster.

    Again thanks for your help guys, it blew my mind how simple it was and how I just couldn't get it. Now the thing is that the bottom cable is nice and round with no kinks in it. This has lead me to believe that the cable stretches a little when its new because there is really no reason now for it to get looser so fast as all the nuts have been tightened. I don't think the kink in the return wire should affect the freeplay at all.

    Again, really appreciate the help given by you guys. It has helped me tremendously and I was able to get everything adjusted with no problem. Funny how something so simple is made so complicated until I finally realised what I was doing haha.

    Attached Files:

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  19. Good work team :)
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  20. You've pretty much got it for this setup. Cables can't really "push" which is what the bottom wire would have to do to snap the throttle closed. While it can sometimes do it, you want to be bloody certain that it will on a motorbike. That's why the two cable system is in use, the top cable will return the throttle by pulling the throttle back and giving the whole system a helping hand. So it's not really an emergency cable or anything, and it's a daft idea to remove it on a road bike. It's your one and only guarantee that when you concentrate on your braking the throttle isn't still kept fully or partially open. Sticky throttles are a very real liability.

    The top cable also just gets tightened onto the holder which will remove any play it has and give you that solid snap to closed throttle. I've never had mine loosen itself up after many long trips, no loctite or alternatives. Judging by your image, the top may still be slightly loose and the bottom slightly tight compared to mine which has as little free play as it should. Best way to check is for clean throttle action in all directions and at all steering angles while the engine idling in neutral and warm. Listen for idle speed increasing as you turn the steering, or check the tacho. Increase free play in the bottom if RPM changes during the test.
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    • Agree Agree x 1