Popping on deceleration !!!
- Thread starter Kinger
- Start date
41bigdawg
Let the Big Dawg eat !
That does look like its getting hot. Gonna be hard to get rid of all the decel pop with those pipes. No baffles either Im guessing? I would check the plugs and see what they look like, would give you an idea if your too lean or rich. Is the carb a Super G or E? I would also do the S&S carb set up first to make sure its adjusted properly. You might need to rebuild it so you know what you got and then go to work with a jet kit till you get it dialed in.
Its a nice lookin bike, with a little work im sure she will be a lot of fun
Its a nice lookin bike, with a little work im sure she will be a lot of fun
Pddain
PHTM II
Here are four links that may help. Reversion, as I recently learned the technical name, may be an exhaust issue only. One of the videos from S&S had an interesting statement, “ deal with the exhaust issue at the exhaust”. I have the reversion issue with baffles installed and short pipes. I have verified no leaks. I am going to try a lollipop next in the form of Thunder torque baffles. I am no expert and will let you know what happens concerning the reversion. I have already verified the carb settings. I have no knowledge on the heat issue.
www.dkcustomproducts.com
www.sscycle.com
Good luck.
Thunder Torque Inserts 258 for Increased HP & Torque
Thunder Torque Inserts™ Increase Low & Mid Range Torque They work w/ Full Systems, Slip-on Mufflers, Drag Pipes and Shortys. Patented.
www.dkcustomproducts.com
Carb Quick Guide | S&S Cycle
Good luck.
I'm with 41 on the plug check and a potential bike of the month. Photo of the plugs would show how rich it is. Paddain wants to throw a lollypop at it, you might try a table top. That's why the plugs would show which way to go.
What fascinated me was the 45° table top throwing off the torque from a 90°.
What fascinated me was the 45° table top throwing off the torque from a 90°.
1 B.M.F.
Well-Known Member
Cheaply chromed pipes blue very easily. Deceleration pop is normal as stated above. I have found that when I twist throttle fast and let off slow that I get a lot less pop. So just shift smooth and less rpm’s. All it is, is unburned fuel exploding in your pipes. They make a cream to rub on your pipes to get rid of the bluing. Tune your carb and roll.
Love that black cherry color. Nice looking horse.
Love that black cherry color. Nice looking horse.
Doesn't look like it's running way too hot to me, a lot of exhaust look exactly like that over time. The problem with that that exhaust is no heat shields to cover it.
Sent from my moto z4 using Tapatalk
Sent from my moto z4 using Tapatalk
Decel pop is normal for a bike with open exhaust and open A/C that has a performance tune.
Decel popping does Not damage your engine...it is simply unburnt fuel that is burning in the exhaust tract after exiting the engine.
But a lot of folks don't like the decel pop and try and tune it out.
Decel popping occurs when one of two things are present.
1. The bike is so lean the exhaust is superheated and is burning the unburnt fuel that is in the pipes (there is always some unburnt fuel in the pipes no matter how lean). This is very rare, and does not sound like it is what you are experiencing.
2. The AFR IN THE pipes is just right to burn the unburnt fuel. This is quite a common occurrence when free flowing pipes are installed (whether or not a free flow A/C is installed). It can also occur if there is an exhaust leak that is introducing extra air into the exhaust tract.
Check for leaks...if there are none, then move on.
To get rid of decel popping a lot of people put MORE fuel than is needed into the engine/over-richening the AFR so that more unburnt fuel goes into exhaust, changing the AFR in the exhaust so that is no longer optimum for combustion in the pipes. This is just a waste of gas.
Decel popping does Not damage your engine...it is simply unburnt fuel that is burning in the exhaust tract after exiting the engine.
But a lot of folks don't like the decel pop and try and tune it out.
Decel popping occurs when one of two things are present.
1. The bike is so lean the exhaust is superheated and is burning the unburnt fuel that is in the pipes (there is always some unburnt fuel in the pipes no matter how lean). This is very rare, and does not sound like it is what you are experiencing.
2. The AFR IN THE pipes is just right to burn the unburnt fuel. This is quite a common occurrence when free flowing pipes are installed (whether or not a free flow A/C is installed). It can also occur if there is an exhaust leak that is introducing extra air into the exhaust tract.
Check for leaks...if there are none, then move on.
To get rid of decel popping a lot of people put MORE fuel than is needed into the engine/over-richening the AFR so that more unburnt fuel goes into exhaust, changing the AFR in the exhaust so that is no longer optimum for combustion in the pipes. This is just a waste of gas.
Mikeinjersey
Well-Known Member
Welcome from NJ,
I had success with Big City Thunder baffles (https://bigcitythunder.com/) finding a balance between performance and sound. In addition to a baffle be sure you have no intake or exhaust gasket leaks. Then watch the videos (Pddain post #3) on jetting and adjusting your carburetor to get the proper performance out of your engine. Keep in mind most likely 90% of your riding is in the mid-range and your motor likes back pressure to maintain performance on the street.
Since the bike is new to you it's probably a good idea to pull the bowl of the carb and clean it just in case it's never been done. While inside take note of your jet sizes in case you need to make a decision on new ones.
Be sure not to adj your bike too lean. Remember no intake or exhaust gasket leaks !!!
I had success with Big City Thunder baffles (https://bigcitythunder.com/) finding a balance between performance and sound. In addition to a baffle be sure you have no intake or exhaust gasket leaks. Then watch the videos (Pddain post #3) on jetting and adjusting your carburetor to get the proper performance out of your engine. Keep in mind most likely 90% of your riding is in the mid-range and your motor likes back pressure to maintain performance on the street.
Since the bike is new to you it's probably a good idea to pull the bowl of the carb and clean it just in case it's never been done. While inside take note of your jet sizes in case you need to make a decision on new ones.
Be sure not to adj your bike too lean. Remember no intake or exhaust gasket leaks !!!
Pddain
PHTM II
Sven: if I can use a table top to increase exhaust gas speed, improve mind range torque and eliminate decel popping, I am in.
Pddain,
As far as pop, no. Think of it like thunder clouds-cold meeting hot and pop/thunder.
The theory is, how do I slow down the speed of air out of a short pipe? Think of a bad set of valve guides being real loose. On the intake stroke, its vacuum is like electricity looking for the shortest way to fill that void back to 14.7 psi. So when you lift going down a long hill say, the car in front has lifted off the gas, then a whoosh of smoke comes out showing a big bellow of smoke and then clears up on sustained throttle.
It's still pulling oil out of that guide each intake stroke, but you don't see it. Add the short pipe, you pulled raw fuel out sort of faster. Let it sit where the blue starts out of the head, then on lift, it was being fired off as fresh air is being pulled in to refire the raw and that is being cooked blue is that raw heating up like the oil sitting there. Except it's gas sitting on lift, not oil. Think of it like that same-same going on.
The lolly/table/bolt... slows the pull of the raw out of the chamber. The raw is power, so you stopped the raw from leaving the chamber and torque is back as the raw fires, not the spent-gas that was mixed back in with the remaining raw and whatever fresh air that has less torque or the raw/fresh/spent making less power.
I'm more the lollypop type you see here. Why? Some hardware parts have the washer [type] welded to a threaded shaft. The washer has a hole already, but say we have a bolt across the pipe already, but a thin washer instead. That's going to slow the speed down out of the pipe as sitting open in the horizontal position.
You're limited with the table moving the up or down and that's more dyno work to see if a few threads and the table's reposition makes a difference. With the lolly, you have a lot more square to deaden the pulse, and can more lock it down in a lot more degree settings. The snuff is either open or closed is the old ad photo, but you get the idea with the hardware ready to go. And I'd move the hole in some so the washer is inside more, rather than the blade or the washer sticking out of the end.
I'd be at the point of taking a needle nose with me and making sure the nut is tight enough to move the washer at the 45° angle and start sending that move up the ass factor and see if you felt any change in torque?
As far as pop, no. Think of it like thunder clouds-cold meeting hot and pop/thunder.
The theory is, how do I slow down the speed of air out of a short pipe? Think of a bad set of valve guides being real loose. On the intake stroke, its vacuum is like electricity looking for the shortest way to fill that void back to 14.7 psi. So when you lift going down a long hill say, the car in front has lifted off the gas, then a whoosh of smoke comes out showing a big bellow of smoke and then clears up on sustained throttle.
It's still pulling oil out of that guide each intake stroke, but you don't see it. Add the short pipe, you pulled raw fuel out sort of faster. Let it sit where the blue starts out of the head, then on lift, it was being fired off as fresh air is being pulled in to refire the raw and that is being cooked blue is that raw heating up like the oil sitting there. Except it's gas sitting on lift, not oil. Think of it like that same-same going on.
The lolly/table/bolt... slows the pull of the raw out of the chamber. The raw is power, so you stopped the raw from leaving the chamber and torque is back as the raw fires, not the spent-gas that was mixed back in with the remaining raw and whatever fresh air that has less torque or the raw/fresh/spent making less power.
I'm more the lollypop type you see here. Why? Some hardware parts have the washer [type] welded to a threaded shaft. The washer has a hole already, but say we have a bolt across the pipe already, but a thin washer instead. That's going to slow the speed down out of the pipe as sitting open in the horizontal position.
You're limited with the table moving the up or down and that's more dyno work to see if a few threads and the table's reposition makes a difference. With the lolly, you have a lot more square to deaden the pulse, and can more lock it down in a lot more degree settings. The snuff is either open or closed is the old ad photo, but you get the idea with the hardware ready to go. And I'd move the hole in some so the washer is inside more, rather than the blade or the washer sticking out of the end.
I'd be at the point of taking a needle nose with me and making sure the nut is tight enough to move the washer at the 45° angle and start sending that move up the ass factor and see if you felt any change in torque?
Jerome Yee
Member
Hey Seven I have a SS on my American Ironhorse and it was Popping like that after letting off the gas, to make a long story short I took it in to the shop and the mechanic changed the plugs and cleaned filter bowl
and adjusted the fuel mixture intake.. It worked cause the Poping stopped completely.. The work he did..
Attachments
Have you considered using torque cones in your exhaust Paul? As opposed to the baffles. I am going to be installing some on the Blow exhaust pipes I got from HDM. Will let you know how that works on mine.
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Jerome, every tune is different. Some you can tune out, some won't. Guy changed the carb on his bike, even the dyno guy couldn't tune it. Power wise, holy shit, but it was an on/off switch to ride. Smokey Yunick said, if you change one thing, there are 5 things you chase and change to correct it or something like that.
john sachs
Well-Known Member
S&S carbs and straight pipes, go together like oil and water.
John
John
Pddain
PHTM II
Kinger, sorry did not mean to hijack.
Thank you all for the input. Mick, let us know how the torque cones work. I inherited the 2” V&H pipes and free flow Air Cleaner but made the mistake of adding baffles which did not solve the back pressure issue nor dampen the reversion. Plugs are clean, intermediate jet was leaned out. The mid range runs a bit rough and reversion is present any time I roll off the throttle. Running 585 Cam. Will check the main bleed air and potentially increase from .040 then test the mid range performance. Next step is pull the existing baffles and add the lollipops. If that doesn’t work then move to mufflers. I want smooth performance through the power band and reduced reversion eliminating decel popping. I like the look of the pipes so working the items above first. Let you know how it goes.
Thank you all for the input. Mick, let us know how the torque cones work. I inherited the 2” V&H pipes and free flow Air Cleaner but made the mistake of adding baffles which did not solve the back pressure issue nor dampen the reversion. Plugs are clean, intermediate jet was leaned out. The mid range runs a bit rough and reversion is present any time I roll off the throttle. Running 585 Cam. Will check the main bleed air and potentially increase from .040 then test the mid range performance. Next step is pull the existing baffles and add the lollipops. If that doesn’t work then move to mufflers. I want smooth performance through the power band and reduced reversion eliminating decel popping. I like the look of the pipes so working the items above first. Let you know how it goes.
Yeah I got the pro baffles for my Blow Exhaust and didn’t care for them in the pipes either that’s why I am going to try the torque cones. My understanding is they work better than the lollipop method.
