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'87 GSXR-1100 idling a bit high when warm??

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by Lectre, Nov 12, 2007.

  1. Hey all.
    My recently acquired 20 year old gixxer seems to be idling too fast, but only when the engine is hot. Now there are two things to consider here in my limited explanation... 1 is that the RPM gauge only starts at 3000rpm (suppose they mustn't have thought it was needed..lol), and 2 there is no temperature gauge.
    I'm aware that these old buggers are only oil cooled, and I try to turn the bike off in peak hour traffic where I can't split, but there are definitely occassions where I have to keep the engine running because if it didn't start again right there, I'm in trouble.
    When I'm not riding it in peak hour traffic, the RPMs go up as well but not as much (about half as much, but how can you tell?). Never does it idle over 3000rpm is about as much as I can say.
    Any ideas anyone? I'm going to take it and get a minor service just for my own peace of mind, but it'd be great to know what's going down with the old girl.
    Cheers :)

  2. OK. they tend to sound a bit busy. 1100 rpm is about right.

    to set the idle stop, it should be almost stalling after about a minute on choke. I find I have to blip the throttle at the first set of lights I get too of a morning.

    The other thing to do is replace the vacuum line to the fuel tap. These things leak a bit when they get old and it get worse when they get hot. It took a while for me to figure this one out, but mine used to slowly rise in revs in my 1 hr trip to work, which meant I couldn't get a decent balance between cold and hot idle and it used to get very hot in traffic.

    Turns out the vacuum line was leaking and slowly leaning out the mixture thus making the bike hotter, thus making the line leak some more. . . .

    If that's all good then it could be the idle mixture settings aren't right. Once you've set the idle speed to deal with warm up, if it's still a problem, then try turning the mixture screws out 1/8 or 1/4 of a turn.
  3. A carb balance might be in order too, and make sure the throttle cable is properly adjusted and not restricting the throttles from closing.