How to Check and Adjust the Throttle

Engine revs at idle – wants to take off when engine is started, before it’s given gas?

The throttle cable is probably attached too tightly OR has sharp turns, causing loss of “free-play”. Relax turns and loosen cable, route cable w/more gradual turns where attached to handlebar and engine.

  • Do not adjust idle screw (C) – this will not restore throttle free-play nor idle engine down.
If unable to relax cable, and the bike still wants to take off when engine is started – adjust throttle cable at carburetor:

  • Loosen Lock Nut (A)
  • Screw barrel nut on carb (B) clockwise (in) – until throttle cable, sitting in connector arm, sits against idle adjustment screw (C).
Check for full throttle:

  • While holding trigger throttle wide open, pull throttle cable (D) where attached to engine – if no movement is detected, you are getting full throttle, no adjustment required.
If movement can be detected when pulled – you are not getting full throttle:

  • Adjust throttle cable at carburetor:
  • Loosen Lock Nut (A), screw barrel nut on carb, (B) counter clockwise (OUT) slightly – then check for cable movement, adjusting in/out as needed.
** IMPERATIVE **
LOCK NUT MUST BE LOOSENED FIRST – BEFORE ADJUSTING BARREL NUT!!! 

fastidle
** For those who did not loosen lock nut first – replacement barrel nuts are available at most small engine sales/service dealers. O/D 6mm
Same size barrel adjusting nut available at many bicycle shops, listed as brake adjusting barrel.