Demon Carburator Tuning

04/06/2014
10 min read

Demon Carburator Tuning

04/06/2014
10 min read

Symptom - Fuel comes out of vent tube or runs out

  1. Lower float level
  2. Decrease fuel pressure
  3. Remove, clean/replace needle-&-seat
  4. Inspect float to ensure it's moving freely

Symptom - Backfires or Pops through carburetor

  1. Open idle-mixture screws
  2. Increase squirter size
  3. Increase jet size
  4. Raise float level

Symptom - Backfires or Pops through exhaust

  1. Lower float level
  2. Decrease fuel pressure
  3. Decrease jet size
  4. Readjust butterfly position, primary & secondary

Symptom - Engine won't start

  1. Prime carburetor with fuel
  2. Pump squirters to get fuel flowing
  3. Check ignition timing

Symptom - Fuel leaks from throttle shafts

  1. Lower float level
  2. Decrease fuel pressure
  3. Readjust butterfly position, primary & secondary

Symptom - Is rich at idle

  1. Increase initial timing
  2. Go in on mixture screws
  3. Readjust butterfly positions
  4. Lower float level
  5. Decrease fuel pressure

Symptom - Stumbles under light acceleration

  1. Open mixture screws
  2. Readjust butterfly positions
  3. Raise float level

Symptom - Stumbles under hard acceleration

  1. Readjust butterfly position
  2. Increase squirter size

Symptom - Won't return to idle

  1. Increase initial timing
  2. Readjust butterflies

Symptom - Surges at part throttle

  1. Open idle-mixture screws
  2. Open primary butterflies & close secondary
  3. Raise float level
  4. Increase jet size

Symptom - Emits black smoke under hard acceleration

  1. Lower float level
  2. Decrease fuel pressure
  3. Decrease jet size

author

Staff Writer
1716 Posts