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High Idle / Revs

Discussion in 'Technical and Troubleshooting Torque' started by bass_player, Jan 16, 2006.

  1. When my Spada is idling it normally sits around 1500rpm but when I give it some revs or when I come to a stop it idles really high and takes what seems like a long time to get back to 1500rpm. Sometimes it stays at 3000rpm too. Ive checked the idle adjuster and pilot screws and all seem to be ok. Any ideas on what could be the cause?

  2. Obvious question first I guess, are the engine revs high or is it just the tacho needle that's showing higher than 1500?
  3. Engine revs are high
  4. gum in the carbie could be making the throttle slide sticky.

    The throttle cable could be sticking. Have you lubed it lately? How about the twistgrip?

    Inappropriate cable routing can also create tight spots. Is the twistgrip[ asy to turn? does it snap back quickly?

    Is the choke closing fully?

    What sort of carby does a Spada have anyway?
  5. Reduce your idle using the idle adjustment knob..... its too high

    If that doesnt help, check your choke cable.... It may be pinched and not returning properly... I sometimes have to wiggle my choke cable to get it to go all the way back to normal (I will get my mechanic to fix it next time I take my bike there)...
  6. Twistgrip snaps shut like it should

    Choke is fully closed.

    Idle adjustment is fine. I have tried turning it so far back that it does not touch the throttle and the problem still persists. Choke is fine too.

    Ill suss out the carbies and give them a clean. If its not that then I guess I'll have to lube the cables. Is that hard to do and do I need any special tools? I like to keep hands on approach to my maintenence and try not to take the Spada to a mechanic unless its absolutely necessary.
  7. I may be misunderstanding you here, but that sounds like you're saying that at one stage you even had the idle adjusted so low that the throttle cable was slack. That's exactly how it should be. When the throttle is closed, there should be a little slack in the cable so that only the idle adjuster is holding the carby open. I like to have a couple of millimeters of slack.

    If this is the first time you've started taking things off the carbies, then I offer you my number one carburettor disassembly tip. Do them one at a time. That way when you can't work out how the first one goes together, you still have the other as a guide.

    (Number 2 tip is to buy a gasket/ O-ring kit before you start. As long as you are in there, you might as well do it properly. Sometimes a new set of seals fixes all sorts of little issues. Number three is to use lots of little plastic takeaway food trays to hold the bits)

    A manual might be a useful thing to have.

    Lubing the cables is not hard, but it can be messy. It depends on how hard it is to free one end of the cable (usually the at on the handgrip end) Some careful exploration should reveal a method.

    Once you have the end of the cable free, there are a number of approaches. I have been known to pull the cable out as far as I can, and put a few drops of oil on it, then work it in and out a few times. Repeat until the other end shows oil. A faster but messier method involves a small funnel and a lump of plasticine or bluetack. Put the end of the cable in the funnel, seal around it with bluetack/plasticine and pour some suitable oil into the funnel. It will eventually find its way out the other end of the cable. When this happens, try to clean up as much of the mess as you can before reattaching the cable.

    Suitable oil does not include WD40.

    I use bicycle/sewing machine oil, because it comes in an easy to use container, but ordinary engine oil should work.

    When you have done the throttle, you'd best do the clutch cable as well. There are two reasons. Firtsly, it will prolong the life of the cable. Secondly, if (when) you do have a clutch cable break, replacing it beside the road in a country town won't be the first time you've tried to work out how it attaches.
  8. I'd have to agree, it sounds like a sticky cable, or a sticking carby slide, especially as it eventually subsides to where it should be. Follow Mike's tips and you should be fine.

    {small bills, unmarked and not in sequence, will do fine, thanks Mike}
  9. Hmmm... Small.. OK, here's a couple of Bigpong bills, and a little gas bill, and here's a dinky little electrickery bill...
    Thanks for taking care of those.

  10. Thanks for the help. Ive got a couple of weeks off from next week so looks like a lot of time will be spent tinkering with me Spada. Thanks again
  11. Before you do anything else bring your current idle down.

    I find with mine that if it is up a little then it also hangs up more after I take it off throttle.

    I would have thought 1100 rpm would be plenty for this time of year

    After that check cables and linkages.

    After that muck around with your mixture (maybe after a carbie clean).

    But definatley try dropping your idle speed first.
  12. This may not be relevant to you, depending on how your carbies are set up, but I had an analagous problem which i fixed recently.

    The problem was that sometimes, after operating at near full throttle, when backing off, the engine wouldn't back off as expected for a few seconds - it was like the throttle was stuck open. Turns out that what was happening was the linkage between the primary and secondary carb was jamming open, so that the primary carb would open, then close as expected, but the secondary carb would be stuck open until vibrations or something popped it back closed. Hence the feeling of the throttle stuck open.

    Fixing it involved a bit of bending of the linkages to give them more clearance. I'm not sure how the Spada carbies are linked, but this might be something to check for.