deceleration popping new slipons
- Thread starter vince1
- Start date
HOLY DIVER
Junior Member
i don't have an answer for that one...wonder if something else is causing it???intake leak or something...if there is no leak a dyno tune will give you your answer
Vince, decel popping is usually caused by unburnt fuel in the exhaust that gets fresh air introduced into the system through a leak from an exhaust gasket, or a seam/joint along the line. Also the scavenging effect plays a role as well and the new slip ons may create a different negative pulse than your old exhaust and actually suck air in from the end of the pipes themselves. This is especially true if you are using the stock y-pipe style headers and the left side can introduce this negative vacuum so to speak. Double check all the silp joints and connection pipes for tightness to ensure there are no leaks. I'm assumine you didnt disturb the exhaust gaskets but just tugging around on the header pipes during the changeover could be enough to develop a leak there also. Recheck there or replace them if unsure. Last thing would be a remap to believe it or not add more fuel to the decel map to quench/cool down and create an overly rich condition making it harder to ignite the charge. It goes against normal thinking and one would think leaning it would improve it, and in a few cases it will. My Gen 3 Dobeck has a decel fuel setting that can be adjusted and is how i was able to rid mine of a moderate decel pop so you may consider that vs. paying about the same for a dealer remap. You will get a discount as a member on the Dobeck so it may not be a bad choice. Unless your running a carb that is 
RibEye
Senior Member
Well said. More free breathing may cause popping, as air is drawn in from the left side pipe of a tourer. True duals would show that to be the case by eliminating decel popping, to the detriment of other factors. Exhaust leak is the first place to look. Please note that free flowing exhaust will pop, especially with stock headpipes. My Hookers could simply not be damped out, period. Others have had the same issue with them. My Monster Ovals pop too, but mostly internally. OEM slipons are different, left to right side. They don't pop without a leak. The left side ones are more restrictive.Vince, decel popping is usually caused by unburnt fuel in the exhaust that gets fresh air introduced into the system through a leak from an exhaust gasket, or a seam/joint along the line. Also the scavenging effect plays a role as well and the new slip ons may create a different negative pulse than your old exhaust and actually suck air in from the end of the pipes themselves. This is especially true if you are using the stock y-pipe style headers and the left side can introduce this negative vacuum so to speak. Double check all the silp joints and connection pipes for tightness to ensure there are no leaks. I'm assumine you didnt disturb the exhaust gaskets but just tugging around on the header pipes during the changeover could be enough to develop a leak there also. Recheck there or replace them if unsure. Last thing would be a remap to believe it or not add more fuel to the decel map to quench/cool down and create an overly rich condition making it harder to ignite the charge. It goes against normal thinking and one would think leaning it would improve it, and in a few cases it will. My Gen 3 Dobeck has a decel fuel setting that can be adjusted and is how i was able to rid mine of a moderate decel pop so you may consider that vs. paying about the same for a dealer remap. You will get a discount as a member on the Dobeck so it may not be a bad choice. Unless your running a carb that is
I too have a Dobeck, which adds fuel on decel, if you want. Popping is greatly reduced. When the extra fuel does ignite in the pipes, during extreme decel, I now shoot little flames. Club members say it looks cool. I don't care much.
Enjoy,
Rich P
J
Jack Klarich
Guest
If you believe it to be an exhaust leak pulling in air try UltraCopper RTV It will seal the fit at the mufflers, tho it may be a bit harder to remove them next time. Back in the Evo days the bikes were shipped from the factory with clear RTV sealant on the mufflers:s
Last edited by a moderator:
dolt
Well-Known Member
The RTV sealant at the muffler slip joint and fresh exhaust gaskets, or re-tightening the exhaust flanges should solve the problem. Actually, I have found that the RTV sealant, if hi-temp, makes removing the mufflers easier. I don't install mufflers without the sealant.
No disrespect to previous posters but there is no reason why there should be any decal popping with any exhaust system. If the system is tight, leak free and the tune is right, there should be no decel popping. Throttle is closed on decel and proper AFR adjustment at closed throttle will eliminate decel popping and any tuner that can't do that doesn't know how to tune.