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VTR250 - carbys cleaned & now idling too high

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by I Adore Vic, Nov 14, 2010.

  1. Hey all,

    Am hoping someone here may have an idea of what might be causing this problem.

    I recently took the carbys apart to sort out a sticking float issue. Adjusted the valves on both carbys to meet required measurements and then took them in to the Honda mechanics (Mornington Honda) for them to check they were right to go back in, which they were.

    Put it all back together again and started it up. A little hesitant at first but then it started. Yay me I think. But then the revs started rising - I let them rise as high as 5000 and then switched bike off. Started again, same thing - revs=4500-5000rpm.

    I checked the throttle cable - made sure it was all as it should be, which it is.
    Checked the front and rear bistarter valves - they look to be working as they should be.

    I know that I need to balance the carbys - am doing that as soon as I get hold of a vacuum gauge - and then I need to do the valves so that I get a close to good as new ride from this bike again.

    However, I want to get this high rev issue sorted out.

    I've ruled out the throttle cable. Ruled out the bistarter valves.
    Ruled out lines being kinked etc. All looks well there.

    Anyone here know what else could be causing this issue?

    Oh, and I've tried adjusting the revs via the idle screw - does nothing...nil...zilch.

    What else should I be looking at/checking?
    What could be causing this?

    Could it be an issue that will resolve once the carbys are synchronised/valves adjusted?

    The only jet I took out/cleaned in the carbys was the main jet. I didn't touch the pilot screw. Could the main jet cause this issue?

    Any help would be appreciated in sorting this issue.


  2. Bummer to hear Rosie. I hope you get the answer you're looking for and it's sorted soon hon.

    Sorry i can't be of help :(
  3. I really truly am no mechanic, but things like...

    Choke working properly?
    Vacuum leak/air intake leak?
    Is your throttle valve closing up all the way - maybe sticking?
    Did you clean and check the pilot screws? Maybe too far in/out?
    Cracks in carb boots?

    ...may cause or contribute to a high idle.
    In my air box cleaning joys i had a similar problem due to a little air getting in around the air intake manifold of the carby. Reseated it and solved.
    P.S. Never adjust or set your carby when your engine is cold. Get it to operating temperature. edit: at least, im pretty sure its meant to be done at operating temp :D.
  4. Thanks Chef. Thinking maybe just pull it all apart again and put it back again, just to see if it makes any difference.
  5. Thanks MrMessy - I'm going to do what I said above to Chef - will pull it all apart again and put back together again then see what happens. Is worth a shot I reckon. Thanks again for your help.
  6. Good luck ;).
  7. OK stupid question, but did you trying winding the idle stop back out?

    After that I would be checking to see if something isn't causing the carbies to lean dramatically. This would include a leaking fuel line, vacuum hoses or dodgy fuel tap.

    After that I'd be suspicious of the float level. The level is set where the valve just closes.

    Also, I know you said you checked the throttle cable, but triple check that the ends of the cable sheaves are seating properly in their seats. If they sit up on a shoulder they can cause this problem.
  8. I know this is insanely basic and I bet you've checked it, but choke?
  9. You need to read the responses above music ;).