| Author | Message | ||
     Mako |
seems like there would be two small pipes and one big one. block off smaller pipes and put tip on bigger one? or vice versa? | ||
| Boogiman1981 |
i sorta kinda did that. you don't want to if you value being able to hear at all | ||
| Figorvonbuellingham |
I opened mine up, cut off the ttwo small ones and cut a two inch hole in the big one. Then welded on a larger tip. I added a used race ecm and a k&n air filter. I have a completely different bike now. I don't think its too loud at all. I can definately hear it at highway speeds now. It was worth the effort and cheap. I wish I could get it on a dyno. I Did all of those upgrades for $165. | ||
| Nillaice |
i think that shortcutting from the rear-most chamber of the muffler right to teh outlets will yeild good results | ||
| Mako |
Cut a 1.25 inch hole in larger pipe and got great low end but up top is suffering from turbulence? I think losing the rear chamber should work well. thanks for sharing your mods, its encouraging. | ||
| Srosenquist |
show photo's? | ||
| Clk92vette |
I am intending to modify my stock exhaust this winter. I have seen photos of the internals and my thought was to cut off the tips, cut the tip feeder pipes back to the second to last baffle plate(right where the small tubes are no longer perforated), and then weld in a larger set of slant cut pipes to direct the exhaust away from the rear wheel assembly. My goals are to increase the low frequency sound volume, keep the rear wheel cleaner, and add a little HP. I was not planning to open up the large main pipe, interesting thought? | ||
| D_adams |
You'll get the first 2 but not the 3rd unless you add a race ecm. If you're doing it yourself, use 1.75" stainless tubing, .065" wall thickness. I posted how to do this several years ago, went through a little bit of trial and error to make it work.  | ||
| D_adams |
 That's the part to take out. | ||
| S21125r |
Anybody ever thought about messing with the front Helmholtz chamber? I read the patent brief for this muffler a while back and I think it's main purpose was help mute the incoming and reflected pulses to and from the cat - i.e. it gives the cat a weaker but longer pulse in which to process spent gases. Supposedly good for 2-4 HP from 5500 to 9000 RPM. Reading between the lines on the supplied graph but it's implied that below 5500 it might actually cost a few horsepower but it wasn't really quantified in the brief. Again that was for cat equipped bikes and nothing was stated to the affect of the chamber on power without a cat in place. If it's there just for sound on non cat'd bikes then it might be a worthwhile experiment to cut it open and weld up the port holes. I assume that will change the tuned length and probably put it more in line with the tuning of the typical slip on system. Reason I think that is because it's no secret that the stock muffler flows really well yet we see guys getting an extra 10 -15 hp with a slip on system. Makes me wonder if the helmholtz chamber is creating a tuned length that is less than optimal for peak HP. On the other hand, Erik and the Elves have probably forgot more about exhaust design than I've ever learned, so I'm not about cut my pipe open :-). Might be a fun experiment for someone though. | ||
| Clk92vette |
Hey Dean I really appreciate your input on this, you are a good guy to enlighten us when you are selling a competitive product to what I am doing. This board seems to be full of some really good people which I don't think is the norm today. And by the way, the pics of the internals that I have are from your posting years ago. I have thought long and hard about creating my own muffler, but ultimately have too many other unfinished projects. And I would buy an aftermarket, but I just do not want to have to repack my muffler every season. | ||
| Figorvonbuellingham |
When I did my muffler mod I did notice some low end loss without a race ecm and K&N. However, the race ecm and K&N was a huge improvement even in the lower end. While testing out the combination I nearly flipped my bike when I nailed the throttle in 2nd. I was expecting the normal wheelie when it came up much harder then I was prepared for, leaving me pulling hard on the bars which gave more throttle in my attempt to hang onto the bike. I believe the noid saved it. Im not too familiar with the noid but this all happened so fast it was hard to tell. All I know is the bike was, what felt to be, past the point of saving and shut completely down and came down hard on the front. Definately opened my eyes to the power increase. I have to relearn this bike all over now. | ||
| Mako |
got it all back together and it runs really smooth at 4k, very little engine braking and not much power, especially above 6.5k rpm. I just put a tip on large pipe and sealed up end of muffler where last chamber starts. I used a couple of stainless scrubbies and a shower drain looking disk to hold them in. I put scrubbies in a hardware wire cage so they stay put. Is it just too lean or is flow all messed up??? | ||
| Mako |
end result  | ||
| S21125r |
Just so I understand your set up - you put the scrubbies inside the 2" pipe that you attached the tip to and then keep those scrubbies in place with a perforated disk also inside the 2" pipe - correct? If so then this might be too much restriction. Lack of engine braking and power suggests maybe too much back pressure/resriction. How did it sound otherwise? | ||
| Mako |
correct. great sound, about half the sound of just the open can. no top end with open can either. I was thinking more restriction with perforated disks and no scrubbies.? just to get it to run better with stock ecm | ||
| Figorvonbuellingham |
When I researched for my mod I saw a few posts where the chamber before the final chamber had been compromrised. The results were not good. That's why I tried to leave the chambers alone and open the pipe inside.it just to get more flow. Did you cut into that chamber? It's hard to see the pic on this little phone. | ||
| Mako |
yes I cut the last chamber off, about ten inches. I will be trying to bypass front chamber next? I think if i can smooth out the flow there maybe the back end will work better? | ||
| Figorvonbuellingham |
The posts I read claimed it was the chamber before the last that people were having bad results with. I was thinking about welding covers over the front part of the interior pipe also. That was going to be my next attempt if I didnt have good results with my initial venture. Luckily it turned out pretty good the first time. Im interested in seeing how it goes for you. I bet it will be louder. It's going to be more like a straight pipe. | ||
| S21125r |
If you cut 10" off then I think you cut out two chambers as the last chamber looks to only be an inch or two deep. From what I can tell in the patent drawing it looks to have 6 chambers - some of those chambers see exhaust at least 2-3 times before they exit to atmo. i.e. the exhaust goes through chambers 1,4,5,6,5,4,3,2,3,4,5,atmo. If you cut off 10" then you system only goes through chambers 1,4,atmo. From a performance vs. weight standpoint you might be better serviced to hack off the rest of the pipe behind the collector and just scab on a glass pack. Or take out the scrubbies and all other restrictions and then pack in stainless wool or fiberglass around the outside of the pipe in the remaining chamber. Sort of a DIY glasspack. Youd have to cut a trap door into the shell for access to the chamber to stuff it though. | ||
| Mako |
only on chamber was cut off. cut from 4 to 10 inches on a diagonal. just wondering if its too lean or a flow problem? | ||
| Mako |
rear chamber  | ||
| Mako |
exit  | ||
| D_adams |
Basically, you've eliminated everything that reduced sound in the stock muffler. The front chamber right off the headers is really all that's left, stuffing anything into the very last remaining chamber does nothing. If you have discs stuffed into the pipe that you've welded on at the end, you're restricting the only direct path out of the exhaust.  The pipe going through the middle is solid with no holes in it until it gets to the 2nd from the last chamber, which you apparently removed.  You have 2 problems, both are what you think it is, flow and mixture. I hate to tell you this, but I'd recommend going back to the drawing board and start over. These pics have been around on the board for several years now, along with a fair bit of testing, trial and errors. | ||
| S21125r |
Hey D_Adams, et al, Anyone ever experimented with just the front chamber that the collector sits in? Looks to be a fairly large volume so makes me think it's targeting a lower frequency. I'm guessing this type of mod would kind of mimic a Torque Hammer system in concept but I haven't really seen the guts of a TH. Thoughts? | ||
| Mako |
thanks for the feedback. is that a c/s or a s/s on front collector with holes in it? | ||
| D_adams |
First one is C/S, 2nd is SS. I have no idea what's in the TH. (Message edited by d_adams on October 17, 2012) | ||
| Mako |
thanks, went to just disks and runs better, now smooth at 5k, rough at 4k. not much resistance as disks have a lot of holes. not too loud? compared to harleys around here... | ||
| Rex |
sure rusty looking on the inside. is this a coating? | ||
| D_adams |
No, it's mild steel, it rusts. |
