I currently have a 2012 Street Glide 103 with 57H cams and open a/c. I have the reversion knock knock at certain rpm's and throttle position.

The exhaust I'm running is a cobra powerport, 4" rush big louie's with 2" baffles

1) Would changing to a different sized baffle or different head pipe quiet the reversion knock?

2) I've also read that changing to 1.75" baffle in left side muffler will help performance. Has anyone tried this with good results?

 

Did you have any headwork done? What fuel tuner are you using and how was it tuned?

 

No headwork yet, that will be this winter

Power Vision with wideband O2 sensors

The bike runs great, no ignition knock, strong top end, runs cool

 

" I have the reversion knock knock at certain rpm's and throttle position."
Are you running a canned map on your PV? Not sure how good the wideband O2 sensors are in compensating for when you are running those lean spots.
You are using a cam with greater duration and lift then stock. You have greater valve overlap because of that. When the setup was being put together, things needed to be put together so you had slightly higher compression and enough backpressure in your exhaust. Then tuning it the right way would have been the finishing touch. Many guys use the 57h cam with headwork, different gaskets, 2 into 1 exhaust systems and Power Visions with good results. If it was my bike, I would take it to a tuner I trusted and figure out a good fix once.

 

Thanks for the reply kojak

Doesn't have anything to do with how the bike runs just the knocking sound.

Map originally came from Fuel Moto and the wide bands made a big difference to getting the bike to run better. Once again the bike runs great and a tune on a dyno may be worth a few horsepower but not worth $300 to $400

 

That knocking/pinging sound (unless you are lugging the engine) is detonation which is not a good thing long term for engine reliability. What I understand you saying is that under most higher rpm ranges, your bike runs fine but on certain spots on the rpm range, your bike is running too lean. If your base map is off, the wideband o2 sensors wont fix the problem. You are obviously concerned enough to check it out, trust your instincts. Your bike has to run right from WOT to steady state and you have spent a lot of money already to improve the performance of your engine. Just saying.

 

Your talking about exhaust reversion and not engine knock right? I'm just a guy that likes to work on his own stuff. I've done a little reading on this. I think it's caused by valve overlap and maybe too large of diameter exhaust. Have you thought about trying torque cones? Might be a cheaper fix than a new baffle although that might increase back pressure and do the trick. Just throwing it out there.

 

Fuel Moto addressed this with their JackPot dyno tuned mufflers, the left side muffler has a smaller baffle opening than the other to help prevent reversion.

 

Kojak
It is not pinging, it is the cam overlap or reversion that I'm hearing and I'm just looking for any way (if possible) to quiet it down because when I ride without the music playing that sound is annoying.

skydude426
That's what I was wondering if you could change baffles or try torque cones to quiet it down. I know that some guys have changed air cleaners with some results but I like the one I have on the bike now and am looking at different options. I do have a set of torque cones that I could install first as that would be least costly solution.

sixguns
I will call Fuel Moto and ask if this addressed the problem and what kind of results thay had with it.

Thanks for the replys.

I'm also thinking about changing out cams this winter when I do the headwork, so any suggestions about similar cams to 57H with headwork and not having as much an issue with the knocking noise I'm all ears

 

I have the same reversion knock on a stock 2015 with a 2-1 exhaust and stage 1 a/c. I had the same knock on my 13 sg with true duals and -57h cams.
I have considered changing exhaust but I really like the 2-1 I am running.