I finished my mods and needed a tuner. Started with 1st Map, No workie so well. Got Map 2 from a different dealer, way better but still no CIGAR. My 03RKC with AirWing/SE A/C, RS511cams and almost straight pipes had a bad decel Pop, sounded like an AR/M16 on 3 round burst every time I backed off the throttle. Ran across a product from a reputable dealer, cheap but shipping was 6x the price of the widget. Looked it over, scratched my head a minute and said, "Well S--T" that's nothing but a automobile engine freeze plug with a center hole drilled to prevent air back flow and igniting the extra gas on the left side. Got the 42mm plug, center drilled a 5/8 hole, had to use drill, grinder stone, wire brush, then VHT to discourage rust as my plug was steel not brass then engine assembly lube to lightly tap into place, custom fit to my exhaust. It fit just inside the left side pipe where the muffler slips on and that heavy clamp holds it in place real well. Loe and behold, no more aggrivating decel pops at all. This custom problem solver is mostly intended for older stock 2 in to 2 pipes like my 03 RKC that use the cross over pipe. That design allows most of the exhaust out the rt side and with way less pressue to the left side it will draw in air. Also found that my rear tuner monitor AFR started registering on the rear cylinder where it had not done prior, I guess all that air draw was screwing with the o2 sensor, but NO More The tuner addressed this issue and said some auto adjust might help but likely not much. Also tuner has a program to cut and add gas at an RPM range but even they said just a bandaid. This 1.00 part modified slightly prevents the air back flow while not restricting the weak out flow causing the problem on my set up. As has been said "Necessity is the Mother of Invention" The auto tune will help over time also can adjust rich or lean on that rear cylinder but all that fine tuning will come in time. Just enjoying the ride for now until I have time to get deeper into the nuts and bolts of using this $$$$$$$ tuner.

 

Glad it worked for you. Always makes me feel good when I solve a problem on the cheap. Lol

 

Yep and I still look just like "THIS" when that happens.

 

When I bought my Night Train it had a terrible decel pop and sounded like crap. It had V&H Short Shots with no baffles.

I got a box of take off parts with it and it included the baffles so I put them in. It didn't quiet down much but it was a deeper and much more pleasant tone. It also completely cured that awful decel pop. Just needed a little back pressure.

 

Just for curiosity and investigation, next time I take my muffler off my basically stock 04, I’ll try to remember to try this and see what happens.

 

Good to hear you are happy with your mod.

Two myths about Harley exhaust-

Decel pops is bad

Backpressure is good

If one does not like the sound of decel pop, there are ways to get rid of it without creating a restriction (which robs power).

Here are a couple of videos on the subject you may find interesting-

 

Clicked on it for the chick…she was a no show

 

Agreed on the myths, especially the need for back pressure.

However, at least on my 04 and the OPs 03, the left pipe is attached to the exhaust almost like a Venturi.

I’ve never bothered to experiment with a bit of tissue paper across the left tailpipe tip, but I suspect there’s quite a bit of inward draw because of that venturi effect.

Equally wouldn’t be surprised if taking the stock exhaust pipe from the rear cylinder, and cutting off the 90 degree stub and covering it for smooth flow would result in some performance improvement.

 

same....disappointed

 

I have herd of that and similar, back at it's worst I covered the lt. pipe with an old pair old shop jeans, wasn't afraid of fire cause that pipe never got that hot to begin with, also the outflow on that side was pitiful. I had never noticed the difference in out flow or had that problem hence never had to start checking in to this issue. origanally had the dealer install D&D cutoffs before I picked up the bike new, no issues then when , after several years and I wanted to change pipes I had installed the OE I had kept stored, now that my friend was back pressure on both sides. Felt like my old 3hp Little Indian mini bike I had when I was 10 years old. and kept them on after boring out the innereds, I had my power and sound back. During the year of upgrades and replacing old worn parts I did get new mufflers, cheap but looked good and very lightly baffeled, The Pop issue started only after the cam install, I think the OE cams were around ..485 lift and the RS511's are .510 lift I'll try to get a pic from up the tail pipe, had one but can't find it as of last night. I looked over the "Myths" and was not concerned with anything but the aggrivating noise. with the addition of my rendition of a commerically sold product only to the left side, It stopped the problem and since the most of the exhaust was flowing out the rt. side, well what little if any restriction there may be on the left side is nill and I can't tell any difference in power. In theory it only/mostly does 99% or better stops the air return back up that left side and gauging by just holding my hand at that pipe, No fancy meters or test equipment seems to have the same amount of air flow out. I'm new to this tuning business and noticed that while running the program the rear cylinder was not registering any movement at all and that concerned me a wee bit. After installing the "Device" and running it the AFR in the program finally registered, it was like magic. it started registering and was hitting the MAP target. There must have been so much air being sucked in it was screwing with the 02 sensor on the rear cylinder. I am real happy with the tuner, sound, power and numbers for now. Amazing what a 1.00 part, modified part did to correct those issues. I'll get a pic today and post it a bit later on.