Motor Won't Throttle Down

Discussion in 'General Questions' started by captbob43, Sep 17, 2014.

  1. captbob43

    captbob43 New Member

    I'm new to these great little machines. Put one on a small trailbike and had to remove the carburetor to fit it. Reassembled the carb and it runs well but won't throttle down so it races at idle or goes too fast in gear. I checked the cable and it seems OK. I may have re-assembled it wrong. Does the C-washer go on top of or underneath the C-clip on the slide needle? Is there a site that shows the assembly sequence? Thanks for any help.

  2. crassius

    crassius Well-Known Member

    washer goes on top so that the spring can hold the needle down
  3. KCvale

    KCvale Motorized Bicycle Vendor

    Yep, and also make sure you have a tiny bit of slack in your throttle cable, you never adjust idle with the throttle cable.
  4. butre

    butre Well-Known Member

    before I got my new carb I was adjusting idle with the cable. the idle screw had fallen out at some point and that was all I could do for a while.

    it was a huge pain in the ass
  5. jhammondcpa

    jhammondcpa Active Member

    I had this happen twice and both were caused by an air leak at the carburetor intake gasket. The original gasket dissolved the fits time and the second was loose bolts, after replacement and tightening the bolts all was back to normal. I also switched to the Dellorto clone carburetor which improved throttle control!