1999 Shadow Aero VT1100c3 with 27300 miles exhaust popping

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  Dpacapt New Member

  7/6/26, 8:47 AM

  I built my own 2 into 1 collector and used a 4" truck turn down open pipe on my Aero without any tuning to the carbs. I rode it that way for many years, sounded GREAT but now it pops a lot every time I decelerate to the point where it is obnoxious. When I say pops it sounds more like a backfire but I'm not sure if that is correct. I tried putting the stock pipe back on it, but it still pops on deceleration. At least it is muffled now but still annoying. Looking to do a complete carb rebuild and tune (re-jet) to be able to put the open pipe back on. Do I need to use velocity stacks, or can I leave the stock intake? Also could I have done some internal damage to the valves or something else.

  Chris

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  TJ Admin Staff member

  7/6/26, 11:51 AM

  @Dpacapt howdy! to respond to your final question - YES. you likely did do some damage. 

  Your open exhaust almost certainly made the bike run leaner than Honda intended. The factory jetting on these bikes is already quite lean for emissions, and removing nearly all exhaust restriction without rejetting generally makes the lean condition worse.

  However, the fact that it still pops with the stock exhaust installed tells me the exhaust itself is probably no longer the primary problem.

  After riding for years and with 27,300 miles, I'd be looking at:

  • A partially clogged pilot jet (very common)
  • A lean pilot circuit
  • An intake vacuum leak at the carb boots or vacuum hoses
  • An exhaust leak at the head pipes or collector
  • Idle mixture screws that need adjustment
  • Carburetors that simply need a thorough cleaning and synchronization
    
    but i wouldnt rule out a burned exhaust valve or piston damage. 

  DO FUN SHIT!
  Check the FAQ's here for tons of tuning info and more!! - t.ly/MA6r6

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