Hello Team:

New Softail Rocker (FXCW) owner here. This is my third bike but first one with the TwinCam 96B engine. Previous bikes: VROD and Sportster Iron 883.

Got the bike used with 21,000+ miles. Vance & Hines Big Radius 2-into-2 exhaust, Screaming Eagle performance air filter. The bike pulls very hard and I like it very much. Love the loudness of the exhaust! on deceleration the bike is also very loud with the "bubble/cracking" sound. How can I get rid of the sound? Is this because the bike is running lean? So far can not find any fuel management system installed on the bike. Wondering if the Vance & Hines LED Fuelpak will be a good upgrade.

Any advice/ideas will be really appreciated. Thank you

 

If the sound on closed throttle deceleration is a "backfire" sound or "popping' sound, the fuel map is too rich on zero throttle. If you lean it to get rid of the popping, be careful to NOT lean the "zero throttle - 1000 rpm" cell, as that will then lean out the idle, which will overheat the bike given enough idle time.

If the sound is more like a "burble", it is normal, and indicates that you are decelerating from a "high" rpm, which suggests you are maybe cruising the bike at an unnecessarily high rpm, OR are downshifting "too early" (i.e. wait longer before shifting down to a lower gear during deceleration). If you have been cruising and close the throttle and get the burbling, you are probably cruising at an unnecessarily high rpm.

Jim G

 

Does the sound bother you? It's not indicative of a problem.

 

Try changing how you ride, how you slow down, stop or downshift.

 

jim, i think it is too lean..not enough fuel.

in other words, he does not have a fuel mgmt device, and the bike is tuned LEAN by the factory, and now, it flows more AIR and needs more FUEL to make it right.

I have always heard it called "lean decel pop"


FWIW, I use a dynojet powercommander, because I can "rough" tune it on my own laptop.

if you find a powercommander screen shot, the left row is "Zero percent" throttle, and that row, from 1500~4500 RPM is where you need to add a bit more fuel. because when you are slowing down, the RPM is in that range, but the throttle is at zero percent (closed)

YMMV

 

The popping can be due to EITHER too rich or too lean. When too rich, it is caused literally by excess fuel that was unburned in the chamber igniting in the exhaust. This is what was happening at one point on my Honda VTX 1800 big twin. Leaning it cured the problem.

But, I want to emphasize I agree with you that too LEAN can also cause the problem.

Jim G

 

If it doesn't have a tuner of any kind it is possible that there are xieds or vieds installed. Before I added the A/C mine had vieds on it with just pipes. They can do an ok job but you are definately better off with a tuner especially with a full Stage 1 or higher. I have Fuel Moto EFI tuner which is basically a Power Commander III, Power Vision is your better choice I just didn't have the extra cash for it.

 

Just to clarify for the OP:

The Power Vision is a tuner that actually modifies the actual ECM in the bike.

The Power Commander, and similar products, is a tuner that merely MODIFIES the fuel (and sometimes also spark instructions) from the ECM before those instrucitons get to the fuel injectors (and sometimes the ignition module). i.e. it takes the "stock" outputs of the ECM and increases or decreases the fuel ratio (and also sometimes spark advance).

The Power Vision is "better' because you are always better off changing the actual ECM versus merely modifying its output signals.

In addition, because the Power Vision type of tuner can also change ANY configurable field or variable within the ECM, it can do lots of other stuff, like correcting the speedometer for example.

Finally, because the Power Vision type tuner has the ability to "read" fields within the ECM, and also has a "configurable display screen", it can display data that a normal motorcycle instrument panel cannot, e.g. head temperature, actual instantaneous mpg, average mpg, gear the bike is in, etc.

Jim G

 

Start shopping for a used V&H Fuel Pak and it should take care of your problem.

 

Not necessarily. I just installed V&H Shortshots, FuelPak, and Big Sucker, and I have the same bubbly sound. I double checked the codes 3 times, and have to contact V&H to see what the problem might be.