homemade exhaust silencers

[Paniller]

Look what I made for $15 and 2 hours:

Parts:
2x aluminum shaft collars from McMasters @ $6.50ish each.
2" OD, 1-1/8" ID

2 more 3/8"-16 set screws for other sides ($1.50ish)
18x 1/4"-20 set screws (optional)

Tools:
Drill press
5/16" drill bill for large 3/8" mounting holes
3/8"-16 tap
13/64 drill bit (optional)
14"-20 tap (optional)
allen keys & rtv for mounting

Instructions:
Self explanatory from picture.

You may want to drill into the muffler and permanently mount down the road. Not sure if my set screw compression grip will stand the test of time on a vtwin.

 

[Paniller]

I'm still waiting for the rtv to dry, but with a 1" test hole washer, my Hawk* sounded about stock. This is 1 1/8", so probably a hair louder than stock with all holes plugged. Opening all the holes is goes another 65% closer to hawk* area again. Not sure how that related to sound level, though.

Numbers
Hawk*/stock 9 outlets(I think): 3.14 area
All holes open: 2.39 in^2 area
All closed: 1.227 in^2 area
each hole: .129 in^2 area

I may have to open it up a hair more, but it's a start, and ideas for you guys if you want to quiet down an exhaust.

* disclaimer: Sloppy looking pipe is not Hawk's doing. Pipe was mangled outside his hands.

 

[Pockets]

Interesting idea. Won't there be slightly more backpressure with the ring in there?

 

[Paniller]

yeah, there will be. I welcome a little more backpressure though, I favor low end grunt.

Randy claimed little to no performance loss with a 2" OD, 1" ID washer in his outlets (I asked how to quiet it down slightly), and this is bigger than that. It's 1/8" wider with all the holes sealed.

Everything's removable, I'll check the fueling to see how it changes, we can see from there if it hurts things.

 

[boosted]

Did you just run those internal set screws in reverse? Whats with the 9 tapped holes you added? Like the idea [up]

 

[Jon0341]

Those look awsome, I was looking into getting something like that to quiet down my Hawk on long rides. I would be interested in buying a set if you were to make more.

 

[Jon0341]

rep point for being innovative!

 

[firebolt020283]

very cool idea.

 

[upthemaiden]

Very nice. I'll probably have to come up with something like this someday. Mine will look significantly sloppier than yours do.

 

[Paniller]

boosted, yes. I just ran the set screws in reverse. Got the idea from some dbdog product or something similar in another thread. They wanted $45 each, and I wasn't having $100 for it. So, I made my own cheapo solution.

The 9 tapped holes are to vary the sound/backpressure. You can add/remove screws to fine tune it if you want. Stock pipe is 3.14in^2, the smaller hole is only 1.2in^2. With those tiny tapped holes, you can tune between 1.2 and 2.39. Oh, and it'll look cool with black set screws.

I'm considering other options, too. 18 screws is a bit much for adjustment on the fly. Plus, I'd like a wider range of adjustment.

If I can find a way for it to be worth my time without charging too much, and to have better quality control to make sure spacing is even, etc, I can make up a few sets for people.

I should probably run it a while first, to make sure it doesn't fall out, the different metals don't seize, etc. I also want some kind of system to switch more quickly, too.

Mine will look significantly sloppier than yours do.

I'm surprised how well it came out, with the tools on hand. Aluminum makes everything look good, lol. Though, it probably should be coated or something, right?

 

[Pockets]

I don't think any coating would be needed really. It's just raw AL and no rust issues aside from the set screws. Rust won't stick to AL. I'd be up for trying a set. How will the set screws be secured in each hole? Vibration is a bitch.

 

[Jon0341]

Ya that was my post about the dbdawgz and as you said they are expensive and costly for me right now.

 

[Paniller]

I'll have to whip some of these up. I think I may want to go with the larger inside diameter ones, though. I'd also like to find a narrower piece to work with, as it doesn't need to be so wide.

Sound: I've only ridden with all holes open. Sounds like a blend between stock and hawk. Less decel popping, and a hair less deep, but still a distinct hawk sound vs stock. Sound level was probably down 25% or more. I was actually comfortable without ear plugs.

So, this is probably what most people would want for sound, so maybe tapping the holes isn't needed for most people. Could probably be a hair louder with all open though, So, I'm thinking like this with plain holes, or larger inside hole on adjustable (tapped) versions.

Power:
Seems a bit smoother from 1800-2300. Though, I think my last tune was too lean in that section, so it's not a fair comparison. I probably could have gotten it this smooth just by fixing the fueling. This adjusted my exhaust to match the fueling, most likely. It may have lost a hair up top, above 5k. For optimal power, probably a hair more open is needed. This setup still works great though, probably pulls similar to stock, or still a hair stronger.

My conclusion from my first trial is that 2 versions would be best:
1: As seen above, don't bother tapping the holes, leave as it is.
2: As seen above, tapped holes for adjustments, larger inside diameter on the main hole.

 

[Pockets]

How would you get a larger I.D.?

 

[Paniller]

They sell a slighter larger ID on that website. They have 1 3/8" and 1 1/4", I think the 1 1/4" would be perfect.

 

[Alfatango1]

Keep us posted, I'd love a set.

 

[mmcn49]

If the set screw vibrates loose try using a nylok set screw. Nylok won't hurt the aluminum threads and will probably hold even with all the vibration.

 

[mmcn49]

Nylok is a locking material that is inserted into a small hole it the side of a metal screw or bolt.

 

[upthemaiden]

The adjustablility looks great. As far as coating them, if someone plans on putting them in and just leaving the on their bike for 2 years, I'd consider painting them so they don't seize. If it's something you keep on your shelf for when you want to be quiet for a week or so I definitely wouldn't worry about coating them with anything. You could put some anti-seize great around the outside but I feel like it would make a mess, and probably get blown out after a few hundred miles anyway. Pick up some stainless steel bolts and you should be set. Some locking washers would probably be all you need for the vibrations.

 

[winnetka]

Pannier, it looks great! You think 1 1/4" ID would be perfect, with or without the 9 holes?

Did you start with the Hawk medium pipe, or the loud pipe?

I really like the fact that you can have an adjustible volume pipe depending on how it sounds and the kind of riding you are doing. I could keep it loud during my daily commute, and quiet it down during the weekend canyon carving sessions.