4 Stroke Carburetion Troubleshooting

Notes on Carburetor

Bike Runs-On or Won't Idle Down When Throttle is Chopped

• Idle set too high
• Air leak in intake or engine
• Pilot too rich (when bike is hot)

Bike Wont Start When Cold Temp Outside

• Pilot jet too lean
• Air filter over-oiled
• Motor oil too thick for temperature

Bike Sputters / Wont Clean Out at High RPM

• Main jet too rich
• Air filter over-oiled
• Spark plug has debris on electrode

Bike Coughs & Stalls in Slow Turns

• Pilot jet too lean
• Idle set too low
• Valves set too tight
• Decompressor is set too tight, so turning the bars engages release slightly

Bike Hesitates or Bogs Over Deep Whoops or G-Outs

• Float level too low
• Carb vent tubes blocked
• Main jet splash shield not installed
• Float level too high, gas is trapped in vent tunes (install T-vents)

Bike Starts But Wont Take Throttle Without Sputtering

• Pilot jet too rich
• Water in fuel
• Debris in main jet

Bike Suddenly Starts Sputtering / Gas Flows from Vent Tubes

• Stuck float check valve
• Debris in gas or carb

Bike Runs Hot / Feels Slow & Flat on Straights

• Main jet too lean
• Fuel octane too low, causing detonation

Bike Coughs & Stalls When Throttle is Whacked Open

• Needle too lean
• Slide cutaway too lean
• Pumper circuit blocked or too lean

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