[eddy k]

my 2002 carburated springer backfires trough the pipes when i let off the

throttle .it has vance hines pipes arlenn ness big sucker and a yost power

tube.any advice would be appreciated .thanks

[chucktx]

what type of backfire are we talking about?? is it a steady pop,pop,pop as you decelerate?? or is it a definate bang?
chuck

[eddy k]

it definatly pops steady.I checked the plugs thinking it ran rich but they don't look bad.they have about 1300 miles on them.they are a little dark.I'll have to check again to see what size jets i have installed thanks. eddy k

[Killer-B]

Nothing wrong with an BANG on deceleration, its pretty common, as long as its not in-between shifts. Cool air is being sucked into the hot combustion camber and igniting. I’m not there to witness it, but I get a bang on deceleration, the harder I’m into it the louder the bang. If you feel there is something wrong, then take it to a trusted indy-shop. (don’t go to Harley, as they will tell you that you need a new motor). JMO.

[chucktx]

when did the backfiring start?? was it after doing some mods or adjustments to the engine?? or all of a sudden?
chuck

[Roadrunner]

Been there done that, still there (somewhat). Eddy my 2001 fxdxt and my 2003 wideglide both experienced the same problem on decel. The harder the loader.
On the wideglide I finally disassembled the entire pipe system (stock header and SEII slip-ons). There is some truth to the air being sucked in the ass end of the pipe which causes some of the popping problem but I also found out that by replacing the exhaust gaskets at the head the problem was cut back by 80 percent. In my case I also used some hi-temp silicone gasket maker at the other connections (since I currently have slip-ons) it guaranteed no airleaks from other areas.

I also just installed a set of VH down curved pipes on my buddy's HD and he experiences very minimal popping. I did change his gaskets as well.

Hope this helps.

[sailordb]

To get the terms correct: Backfiring is when combustion starts before the intake vavle closes and the flame front retreats into the intake (under combustion pressure); afterfire is when the combustion is still in progress when the exhust vavle opens and the flame front burns in the pipe.

Popping on decelleration is, generally, caused by vavle overlap, or a rich mixture. Popping through the carb is, generally, timing.