Too much play in throttle cable - won't idle

Discussion in 'Frame Mounted Engines' started by jbbishop, Jun 21, 2009.

  1. jbbishop

    jbbishop New Member

    Ok so I've got one of those 80cc engine kits.

    The idle screw is turned out 4 and 1/2 turns. There is no point in playing with the idle screw right now because there is way too much play in the throttle cable to keep the engine from shutting off when the throttle is released. Yes, by twisting and holding the throttle far enough it would idle with the clutch engaged. I did not have the problem on the first bike that was stolen but I had this same problem on the second bike that was stolen and just lived with it. Now the case with this third bike the play is even worse than the last one, so I'm wondering if anyone has any ideas on how to resolve this problem.
    Last edited by a moderator: Jul 1, 2009

  2. biken stins

    biken stins Member

    Try a spacer on top of carb where cable goes in. That is if your other cable adjusters are positioned correct.
  3. Hawaii_Ed

    Hawaii_Ed Member

    It should idle with the tension off on the throttle. All the way in is max idle, the screw bumps the slide open as you screw it in. If you are 4 1/2 out, try screwing it down.
  4. will_start

    will_start Member

    I had this problem, the throttle would get stuck or seemed have a lot of free-play before
    it started the turn.

    What the guy with the hot wife said, may work.
    the adjusters on top of the carb are what I used however, and it stopped the throttle
    being loose.
  5. jbbishop

    jbbishop New Member

    The existing cable adjusters are already turned out as far as they can go both on top of the carb where the cable goes in and at the housing where the cable threads into the throttle. It seems the logical idea. I'm not sure what kind of spacers or how to attach them but I'll look closer and consider the matter further.
  6. Hawaii_Ed

    Hawaii_Ed Member

    It should be able to be adjusted out, the 90 degree bend at the throttle can thread in a long ways too. But the engine should idle with no throttle cable at all if you get it set right :)
  7. jbbishop

    jbbishop New Member

    I didn't realize or remember that it should idle without any tension on the throttle cable but that only makes sense. I'll play with the idle screw a little and see what I come up with. In the meantime I did ransack a bunch of old bikes in the backyard and came up with a whole bunch of spacers from standard cabling accessories that should take up the slack. Thanks again.
  8. Hawaii_Ed

    Hawaii_Ed Member

    If you are using the throtle cable to make it idle, you are actually bypassing the idle screw. Turn the screw all the way in, and it should idle, then back it out to bring it down. Mine is about 1.5 turns out on my new motor. The bigger issue with the throttle cable is if it is too loose you will not get full throttle. I saw this on a drag car, my friend was running slow for what his setup was. I had him mash the gas, and then pushed the lever on the carb about 1/4 more. He was only at 3/4 throttle because of a lose linkage :)
  9. jbbishop

    jbbishop New Member

    My first bike I got to idle but adjusting the throttle cable tension was a big part of the trick in getting the idle nice and even - although the idle screw did clearly perform its function properly in that case and caused the engine to rev up or down depending on the direction it was turned. That was not the case on my last bike where it seemed to have no effect and the same appears to be the case here. Thus, it seems likely, based on the little I've read, that there is air leakage in the carb. I think I'll need to go with the o-ring and permatex option in attaching the carb to the intake manifold and see if that makes a difference. I'll also work on the throttle cable issue tomorrow and see if I can take up the slack.
  10. take off the aircleaner and look in carb,turn in screw and you can see the slide in carb go up a little,put air cleaner back on.
  11. rjs5700

    rjs5700 Member

    jbbishop........If you wait a while the third bike will get stolen and the fourth bike might idle OK.
  12. jbbishop

    jbbishop New Member

    Yeah, well for the moment the bike is secured with a U-Lock inside of a locked garage. That probably won't stop the fiends for long.

    As for my other issues: I was able to clear up both the leak from the drainage screw on on carb and the idle issues by simply putting a few more turns on the clamp holding the carb to the intake, without resorting to an O-ring and Permatex. As pointed out earlier the play in the throttle cable isn't that great of a deal only it may be preventing full throttling and I'll work on that later with the collection of spacers I collected from used bike parts.

    Thanks again for all the input.