Table of Contents

11.9.1 Deceleration Popping Causes


MOST COMMON: Exhaust Changes: Make sure none the mechanical causes below are a factor and move on to fixes via ECU control.

Weak Fuel Pumps or Low Fuel Pressure: Always check fuel pressure before you even start tuning a motorcycle. Yes, even the ones with 500 miles on them. A weak or failing fuel pump can be tricky. Sometimes it will only impact the motorcycle at a higher RPM or under load. Another reason to try to catch any sign of it early.

Clogged Fuel Filters: Replace/clean.

Plugged slow jets/injectors: If the bike never had this issue and recently started popping after sitting for a long time then having plugged slow jets is not uncommon.

Low Quality Fuel: Use a premium fuel. Consider cleaning the lines with appropriate fuel cleaner.

Removing Baffles: The function of baffles on an exhaust are to reduce to the deceleration pop by not allowing all the air to enter exhaust and ignite the unburnt fuel.

Intake or Exhaust Leaks: Check for intake and exhaust leaks, have them sealed and fixed.

Riding Style: Flicking the throttle (rev matching) during decel can cause an influx of fuel and air for just long enough to create conditions conducive to popping. This can be resolved by resisting the urge to flick the throttle during deceleration.

Installation of Exhaust: If the exhaust is not properly aligned, installed and tightened then you will have issues with deceleration popping. Double check to make sure everything is aligned correctly and tightened down.

Loose Exhaust Nuts/Bolts: Exhaust nuts can become loose from everyday riding, ensure that all the nuts are tightened and aligned properly.

Emission Control System: Some emission control systems on motorcycles can cause deceleration pop due to them automatically injecting air into the exhaust. (i.e. california bikes)

Bad Wiring in the Ignition: If the wiring in the ignition is not wired properly this can cause the popping as well as timing issues. I hope you never experience this.

Catalytic Converter: With a catalytic converter on, it will reduce the deceleration pop but if it is damaged or taken off then you will experience more exaggerated popping.

Installation of Exhaust: The air flow sensor is what dictates how much air is being released into the fuel injection engine. If the sensor is damaged or defective it can cause deceleration pop. Some symptoms of a defective sensor are:

  • Hard to start or turn over the bike
  • Bike stalls out after starting
  • Hesitation or stutter during acceleration
  • Extreme richness or leanness during idle

Crushed Exhaust Gaskets: If the exhaust gaskets were crushed from last exhaust install, it will create issues.