Exhaust System Topics New and old exhaust system discussions. Fitment issues to sound bites and suggestions. Post them here.

Supertrapp

Thread Tools
 
Search this Thread
 
Old Aug 2, 2009 | 07:38 AM
  #1  
wulffe's Avatar
wulffe
Thread Starter
|
Tourer
Joined: Sep 2008
Posts: 440
Likes: 1
From: NW Burbs of Chicago
Default Supertrapp

Just installed a Supertrapp 2 into 1 system from a salvage bike.

It seems a little quiet to me and I think it may have a low disc count. I wanted to pull the discs that are in there to see whats what but I'm not sure how and the website instructions are unclear.

There are two bolts on the outside of the pipe and then several on the end cap. I removed the bolts from the outside of the pipe and the discs did not come out easily. Is this the way to remove them? I didn't want to start messing around and break things until I understood I was at least on the right track.
 
Reply
Old Aug 2, 2009 | 08:23 AM
  #2  
Dalton's Avatar
Dalton
Ultimate HDF Member
Joined: Feb 2007
Posts: 7,663
Likes: 7
From: Northeast Ohio
Default

There should be 6 screws/bolts around the perimeter of the end cap. You pull those and the discs will come out. Supertraps can be very quiet with a closed end cap. There is also open end caps available that will increase the volume. Open end cap = less discs needed. Closed = more discs needed. An open end cap will equal about 6 - 8 discs.
 
Reply
Old Aug 3, 2009 | 08:03 AM
  #3  
wulffe's Avatar
wulffe
Thread Starter
|
Tourer
Joined: Sep 2008
Posts: 440
Likes: 1
From: NW Burbs of Chicago
Default

Thanks, man. I'll have to order up some discs or a different endplate. I had heard about fewer discs = quieter, higher torque, and lower horsepower so I'll have to get some discs and play around. I do like the difference I feel even with the way it's setup now. I was afraid this was going to be one of those mods where the 'improvements' are too subtle to be felt in my pants seat.

Any trouble likely reinstalling the 'disc pack' once I pull them out? Looks like the bolts tprobably thread into a plate in the back but lining up a bolt into a blind hole while managing 20 discs sure sounds like it could be a PITA but maybe not.
 
Reply
Old Aug 3, 2009 | 08:40 AM
  #4  
Hillsidecycle.com's Avatar
Hillsidecycle.com
Sponsor
Joined: Dec 2007
Posts: 12,084
Likes: 829
Default

We work with 3-disc increments on the dyno here, continuing to add until you JUST start to witness the low end torque start to drop. At that point, we back up 1-2 as needed.
This is done while running the closed end cap.
Scott
 
Reply
Old Aug 3, 2009 | 09:47 AM
  #5  
paul s's Avatar
paul s
Outstanding HDF Member
Joined: May 2008
Posts: 2,166
Likes: 4
From: la
Default

I had SuperTrapps on my '85 900 Ninja, being a youngster and looking to cut corners on cost I added small washers instead of more discs, it worked pretty good.
 
Reply
Old Aug 3, 2009 | 03:05 PM
  #6  
Hillsidecycle.com's Avatar
Hillsidecycle.com
Sponsor
Joined: Dec 2007
Posts: 12,084
Likes: 829
Default

Me thinks, that the shape of the patented disc, and the correct spacing between, is very instrumental, in the tuning results of the Supertrapp system.
Scott
 
Reply
Old Aug 3, 2009 | 08:06 PM
  #7  
wurk_truk's Avatar
wurk_truk
Outstanding HDF Member
Joined: May 2008
Posts: 2,543
Likes: 19
From: Ashland Ohio
Default

Scott

Do you have the best luck (torque curve) with the closed end cap?

Thanks
 
Reply
Old Aug 4, 2009 | 04:54 PM
  #8  
Crazy Canuck's Avatar
Crazy Canuck
Outstanding HDF Member
Joined: May 2005
Posts: 2,525
Likes: 4
From: Montreal, Canada
Default

No biggy. Just thread the screws through the disc's first. Then "apply" some Permatex copper anti seize to the threads of the screws sticking out of the disc's and then fit the hole unit as one piece. Everything should line right up. Maybe a little wiggling will be needed but not to bad of an endeavor. Remember, don't over torque..... 15 to 25 inch/lbs for 4" disc's and 40 to 50 inch/lbs for 5" disc's.

Originally Posted by wulffe
Thanks, man. I'll have to order up some discs or a different endplate. I had heard about fewer discs = quieter, higher torque, and lower horsepower so I'll have to get some discs and play around. I do like the difference I feel even with the way it's setup now. I was afraid this was going to be one of those mods where the 'improvements' are too subtle to be felt in my pants seat.

Any trouble likely reinstalling the 'disc pack' once I pull them out? Looks like the bolts tprobably thread into a plate in the back but lining up a bolt into a blind hole while managing 20 discs sure sounds like it could be a PITA but maybe not.
 
Reply
HD Forum Stories

The Best of Harley-Davidson for Lifelong Riders

story-0

7 Times Harley-Davidson Chucked Tradition Out the Window

 Verdad Gallardo
story-1

7 Surprising Harley-Davidson Products that Are Not Motorcycles

 Verdad Gallardo
story-2

8 Best Harley-Davidson Motorcycles Ever

 Pouria Savadkouei
story-3

10 Worst Harley-Davidson Motorcycles Ever

 Pouria Savadkouei
story-4

Killer Custom's Jail Break Is The Breakout That Refused to Blend In

 Verdad Gallardo
story-5

Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?

 Verdad Gallardo
story-6

Harley-Davidson Reveals Super Cool Cafe Racer Concept

 Verdad Gallardo
story-7

Engraved Rebellion: Inside Bundnerbike's Glam Rock II

 Verdad Gallardo
story-8

10 Motorcycles You Should Never Buy

 Joe Kucinski
story-9

10 Things Harley-Davidson Needs to Fix in 2026

 Verdad Gallardo
Old Aug 6, 2009 | 08:05 PM
  #9  
2000FiveOh's Avatar
2000FiveOh
Tourer
Joined: May 2009
Posts: 315
Likes: 1
Default

As already said, just pop the 6 screws out of the end cap and the cap and discs come right out.

As far as open or closed end caps are concerned, I feel it performs the best with a closed cap. I have an open end and played around with it, but always ended back at 20 discs and a closed cap. The open cap wasn't much louder, but I definitely felt the low end vanish with the open end. I tried open with 8, 10, 12, 14 and didn't like the way any combos felt.

Overall. it's a good pipe performance wise, but I hate the sound.
 
Reply
Old Aug 7, 2009 | 06:06 AM
  #10  
wulffe's Avatar
wulffe
Thread Starter
|
Tourer
Joined: Sep 2008
Posts: 440
Likes: 1
From: NW Burbs of Chicago
Default

Thanks, all.

This was setup with 8 discs and a closed end cap so Ill be ordering up the 12 pack of discs.

Good advice on the torque and antisieze. I wish someone had told the guy who set this up. Two of the bolts were tight. One I got out. The other snapped at the top on the first turn. Looks like aluminum bolts. Non-ferrous anyway

Is the use of 'copper' anti-sieze critical? My chem shelf is getting awfully full. I use regular Permatex anti-sieze (http://msds.ihs.com/partinfo.aspx?partid=40947).

Also on replacing the bolt that broke do you think using SS in place of the aluminum would be OK?. I hate to buy the 'pack' of bolts Supertrapp offers to use just one.
 
Reply



All times are GMT -5. The time now is 06:48 PM.

story-0
7 Times Harley-Davidson Chucked Tradition Out the Window

Slideshow: Harley-Davidson built its reputation on nostalgia, but every so often, the company took a hard left turn into the future.

By Verdad Gallardo | 2026-05-20 11:18:19


VIEW MORE
story-1
7 Surprising Harley-Davidson Products that Are Not Motorcycles

Slideshow: The bar-and-shield logo shows up on far more than motorcycles, some of the company's most unexpected products have nothing to do with riding.

By Verdad Gallardo | 2026-04-29 16:50:35


VIEW MORE
story-2
8 Best Harley-Davidson Motorcycles Ever

Slideshow: Not every Harley gets it right, but these are the ones that genuinely earned their reputation.

By Pouria Savadkouei | 2026-04-15 14:23:21


VIEW MORE
story-3
10 Worst Harley-Davidson Motorcycles Ever

Slideshow: From the troubled AMF years to modern misfires, these bikes earned reputations for reliability issues, questionable engineering, or disappointing performance.

By Pouria Savadkouei | 2026-04-01 20:01:09


VIEW MORE
story-4
Killer Custom's Jail Break Is The Breakout That Refused to Blend In

Slideshow: Killer Custom's "Jail Breaker" build focuses more on stance and visual aggression than mechanical overhaul.

By Verdad Gallardo | 2026-03-18 19:20:32


VIEW MORE
story-5
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?

Slideshow: The Swiss custom shop has taken a Harley Softail and stretched it into something so long and low that it looks closer to a rolling sculpture than a conventional motorcycle.

By Verdad Gallardo | 2026-03-07 16:15:30


VIEW MORE
story-6
Harley-Davidson Reveals Super Cool Cafe Racer Concept

Slideshow: Harley-Davidson's new RMCR concept revives the café racer formula with modern hardware-and it may be exactly the reset the company needs.

By Verdad Gallardo | 2026-03-04 12:23:37


VIEW MORE
story-7
Engraved Rebellion: Inside Bundnerbike's Glam Rock II

Slideshow: A standard cruiser becomes an intricate metal canvas in the hands of a Swiss custom house known for pushing Harley-Davidson platforms far beyond their factory brief.

By Verdad Gallardo | 2026-02-24 18:19:44


VIEW MORE
story-8
10 Motorcycles You Should Never Buy

Slideshow: There is no shortage of great motorcycles to buy, but we would avoid these ten.

By Joe Kucinski | 2026-02-19 14:50:51


VIEW MORE
story-9
10 Things Harley-Davidson Needs to Fix in 2026

Slideshow: Harley-Davidson's challenges aren't abstract; they show up in dropping shipments, shrinking dealer traffic, and strategic decisions that aren't yet translating into growth.

By Verdad Gallardo | 2026-01-13 18:33:17


VIEW MORE