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I recently picked up my new CSC Viper conversion on my Goldwing 1800. After 700 miles of riding the new machine, I love the riding aspects of the kit. Handling is good, (bad Michigan roads can bring out the bad in the suspension though), but otherwise I enjoy riding it, suspenion-wise.

But I find I'm sensitive to the exhaust design of the CSC Honda Viper kit.

Here is an email I sent to the dealer that installed it. They did a super job and are also seeing if they can offer any support for me on this issue.

Would like to know what other's think, or have maybe done.

Andy C.


Dear Xxxx,

I have a good friend who worked at Bosal for a number of years, designing auto exhaust systems for GM and others. I had a long conversation with him two days ago, and shared pictures and data with him. He had a number of thoughts on the CSC exhaust design:

  • He feels that the rubber isolators are not functional. He concludes as I have been suspecting, that the muffler mounts themselves are putting energy into the trike frame. I feel this through the machine, especially under acceleration.
  • He suggests the the mufflers should be hung like a car exhaust, with donuts and hangers.
  • He says that the mufflers should have ribs stamped in them, and that the CSC mufflers are oil-canning. To whatever degree this is occurring, this acts as a speaker. And combined with the close proximity to the trike trunk area, are definitely transmitting some level of sound and vibration into the body.
  • He notes that the exhaust end caps don't utilize any domes or indents related to tonal control.
  • That the muffler looks to have been designed primarily as a weldment to fit the application. Not so much as an Engineering exercise in NVH control. (especially for a Goldwing cruiser, with an entertainment/Nav center)

My friend's thought is that the muffler hangers/mounts transmitting vibration into the structure, are the largest contributor to what I'm finding objectionable.

I talked to Will at CSC this morning:

  • The muffler system I have is the latest design, quieter than their older designs.
  • They Measure them as (Only) 2db louder than stock, at 12" from the tail. (Note that 3db would be twice as loud....).
  • They've tried softer isolators, they can wear out in as little as 60 miles. (Makes me think that they know they're transmitting vibratory energy into the structure, and had hoped to reduce the levels).
  • Muffler is stainless with baffles.
  • 1 Person/year complains, I'm the 2019 person.
  • No knowledge of any customers trying to improve isolation or shielding of the sound. "Most want it louder".
  • "Trikes will just be louder, due to more tire contact and larger fiberglass structure". (I'm not hearing road noise).

He wasn't particularly apologetic or empathetic to my criticism of the design of their exhaust system, but I suppose if you don't have any mitigation for a customer that's sensitive to it, you're not going to be. I guess I understand. I raced amateur level Sports Cars for 25 years, I'm pretty sensitive to vehicle sounds and handling...

Current Plan of attack thoughts: (After the riding season ends)

  • I ordered a pair of insertion attenuators ($25). Mostly to see how much of the rear exit exhaust sound I'm hearing as objectionable. Will try them without any other changes.
  • Remove the mufflers and see how much Dynamat/Thermo-Tec/Super sound deadener, or other sound deadening material I can install adjacent to the mufflers, and underneath the rear structure.
  • See if I can modify the muffler installation to utilize Automotive style "Donut" hangers. This will be the tricky part. If done incorrectly, it risks too much movement of the mufflers, or falling off in the middle of Idaho...
  • See if we think the mufflers are oil canning enough to want to try to stiffen the flat faces. Tougher to weld anything to them, with stainless.

Beyond this, get earplugs I guess. Which I did try but they further prevent hearing the radio and Nav system. And not as safe relative to riding and potential dangers. Maybe there's helmets with more isolation in the ear sections. And there's the famous Goldwing intercom headphones/speakers. (But after years of riding with the wife on a Harley, we weren't so sure we wanted to talk to each other going down the road!) I have a loud bike (Harley Road King), I wanted a quiet one!

Andy C.
 

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I’m assuming the mufflers on your trike are the repositioned OE’s.
On my Lehman conversion....a double 90* bend is added between the catalytic converter and the mufflers to lower them bellow the rear suspension.
I think this offset may have something to do with the higher level of noise compared to the stock 2 wheel Wing.
I have more of an issue with the tire noise the trike emits from the back wheels.
I don’t have running boards.....so I wonder if they would cut down on the tire noise (although I don’t want to install them).
I enjoy my trike.....the noise is just a byproduct of owning one.
I assume you are planning to install the attenuators inside the mufflers....how is that going to work?
Curious minds!.....:chat:
 

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I like the sound of my 2014 CSC Cobra kit. I assume it is similar to your. It’s only a little louder than stock but not too loud for me. I don't notice any exhaust vibration being transmitted to the trike. The only change I made was to replace all the u-bolt clamps with stainless steel.
 

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Not true, I've complained about the loudness of the pipes on my Cobra XL. I was told that they couldn't use the stock mufflers due to the routing of the exhaust pipes. I would prefer that it sounded like it did when it was a 2 wheeler.
 

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In my opinion, "LOUD" = SAFETY!!!!!!!!! Maybe that's just an old Harley guy talking, but I feel like loud pipes saved my bacon more than once over the years!
I love the DCT on my Gold Wing, but I miss pulling the clutch and revving the engine to let some idiot know he’s not the only one on the road.
Jim
 

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Following this because I just ordered a CSC Cobra XL kit for my 2006 Gold Wing.

I downloaded the 34 page Installation Instructions for the kit. Page 30 shows the first two steps and two pictures of how the stock OEM mufflers are removed and replaced with strait pipes that attach to the new large rectangular CSC muffler assembly at the back bottom of the trike kit frame.

It shows the four locations where the "rubber sandwich mounts" and nyloc nuts hold the muffler to the trike kit frame.

Thought this might provide some insight on how the exhaust system looks on the kit. Viper kit is probably the same.
366175

I wonder if you could shove something between the top of the muffler and the T-shaped black frame of the trike kit that would help dampen some of the muffler vibrations? Whatever it is, it would have to be heat resistant, somewhat pliable but not super stiff. Just a thought.
 

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Following this because I just ordered a CSC Cobra XL kit for my 2006 Gold Wing.

I downloaded the 34 page Installation Instructions for the kit. Page 30 shows the first two steps and two pictures of how the stock OEM mufflers are removed and replaced with strait pipes that attach to the new large rectangular CSC muffler assembly at the back bottom of the trike kit frame.

It shows the four locations where the "rubber sandwich mounts" and nyloc nuts hold the muffler to the trike kit frame.

Thought this might provide some insight on how the exhaust system looks on the kit. Viper kit is probably the same. View attachment 366175
I wonder if you could shove something between the top of the muffler and the T-shaped black frame of the trike kit that would help dampen some of the muffler vibrations? Whatever it is, it would have to be heat resistant, somewhat pliable but not super stiff. Just a thought.
Very interesting. My 2014 Cobra kit exhaust system looks nothing like that. I have two mufflers and a bunch of short pieces with u-bolt clamps, 5 per side I think. This looks much cleaner.
 

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Very interesting. My 2014 Cobra kit exhaust system looks nothing like that. I have two mufflers and a bunch of short pieces with u-bolt clamps, 5 per side I think. This looks much cleaner.
I suppose it would sound much different also.
 

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OK, I'm back now that I have picked up my 2006 Gold Wing with the new 2020 version of the CSC Cobra XL trike kit installed. (The muffler looks like the one I posted a picture of in my earlier post in this thread.)

So far have only ridden it home from the dealer/installer, a 75 mile ride on mostly highways and Interstate highways.

My observations regarding the exhaust sound:

1. At idle standing next to the bike with no helmet on, the exhaust note and level seems almost the same as the stock mufflers. Also, when revving the engine, the exhaust note sounds like stock as well.

2. At "cruise/coast" on the highway at speeds anywhere up to 70 MPH with a helmet on, the exhaust note/level seems to be about the same as stock as well.

3. Upon acceleration, at any speed, with a helmet on the exhaust note/level is louder than stock but not annoyingly louder. But it's almost a "drone" sound, which I find a bit annoying but tolerable because it stops as soon as you stop accelerating.

So, item #3 is the only thing I find different than stock and to me a bit annoying. That said, I think I'll get used to it pretty quickly.

The OP says that he "feels" energy being transmitted through the frame by the exhaust system. I don't "feel" it particularly, but I hear it. I'm wondering if most of that comes from the big fiberglass trike body amplifying the exhaust noise like a bass reflex port on a large home stereo speaker.

Also, the "boss" has not yet had a ride on the back seat! I'm not going to say anything to her about this and I'll see if she notices anything enough to mention to me after her first ride on the trike. She's pretty particular, so if she hears something that's different, she'll tell me. I'll report back again if she has some input.

Gonna have to get some side panels for my TCML table lift so I can get this thing up in the air and look around under it!

...
 

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WingMan, my guess is the helmet is amplifying the sound; see if you can find a stretch of highway wear you can take off your helmet for a test.

My Wing is a 2018 with a CSC and has no highway drone sound; however, I've noticed my helmet creates a reverberation type sound as if you were going through a tunnel on every bike I've owned,.

Conrads on the conversion!
Jim
 

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I don't think so Jimer. Same helmet since I've owned the bike and this is a new sound with the trike conversion. I still say it's the trike fiberglass body amplifying the exhaust sounds like a speaker box.

I'm liking the trike. It will keep the wife and I riding in our "old age"! I've still got some lighter two-wheeled motorcycles in the stable so I can get out and lean into some corners by myself once and a while.
 

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Well, the boss has had her first ride on the back seat. I made no mention of exhaust noise before the ride.

Her first comment when we got back was "it's really loud now, way louder than before."

So, she heard what I heard only worse. Noise is worst when accelerating. Tolerable but annoying when not.

CSC has some work to do on their latest exhaust/muffler system. We're not a fan. Love the trike kit but not the increased exhaust noise.
 
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