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3rd April 2023
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XL FORUM TEAM MEMBER
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Join Date: Oct 2008
Posts: 1,093 Sportster/Buell Model: Sportster Sportster/Buell Year: 1990 Sportster/Buell Model #2: Sportster Sportster/Buell Year #2: 1975 Other Motorcycle Model: Buell S1 W Other Motorcycle Year: 1998
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Quote:
Originally Posted by Randy_rots
You have to understand that your current SuperTrapp is very different from the one I suggested! Just get rid of it and buy SuperMegs for 2004+ and you will be surprised!
Have a look at the results on the Hammer Performance web done by Aaron and you will see what I mean 
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Yes i know is different. But even looking at the dyno page of Aaaron (I consulted many many times this page...) , basically the disc system , can shifts the torque curve, but at the end you loose to much torque (even if it s earler) with less discs compared to many discs.
About the Hammer Performance Page I also tried the 2:2 with the RUSH slip-ons, to try to flatten the TQ curve. But I never been excited by this system.
here what I tried to build today
I welded a tube to an open Supertrap end cap, originally with a rotary disc to hold with a screw to partially cap the system.
I put a threaded bar through, and put a cake mold to block some flow.
I'll try tomorrow and I let you know the results.
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1990 Sportster Axtell 90 ci, CP Carrillo 3.875 30° deg pistons,STD Heads, 615V2 RedShift cams, HSR48,
Carrillo 6.938 rods (All HammerPerf)
Hammer Billet Sledge air filter
Hammer Billet Manifold.
160/60ZR17 rear on Akront 5.50" Alu rim
100/90-19 front on Akront 2.50" new Alu rim
YSS 13.75 rear shocks
1975 XLH almost stock
1998 Buell S1W almost stock
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4th April 2023
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XL FORUM TEAM MEMBER
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Join Date: Oct 2008
Posts: 1,093 Sportster/Buell Model: Sportster Sportster/Buell Year: 1990 Sportster/Buell Model #2: Sportster Sportster/Buell Year #2: 1975 Other Motorcycle Model: Buell S1 W Other Motorcycle Year: 1998
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I made a road test.
Nothing special. I feel it more "soft" , probably with little gas opening the 2000 to 3200 rpm are more effective. But I feel a torque decrease (3700-to 4800-5000) when the other system (all OPEN) start to REALLY SHINE (around 3800 and UP to rev limiter).
Unexpectedly , at 5000 rpm , it start to gain torque again (probably after that torque dip ends, I feel it strong).
I removed it and I made another system with the same device used before BUT with spring loaded cap.
It needs to breath more? the cap will go further out because of RPM/load .
I'm not expecting it works (I'm expecting to loose it on the road...LOL)
Here the pics:

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5th April 2023
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XL FORUM TEAM MEMBER
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Join Date: Jun 2008
Location: On a big rock in the Florida Straights
Posts: 572 Sportster/Buell Model: XL 1200 S....X Sportster/Buell Year: 1999 Sportster/Buell Model #2: XR-1000 RX Sportster/Buell Year #2: 83 Other Motorcycle Model: SOLD - RZV500R/R1 hybrid Other Motorcycle Year: 1984
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yep supertrap and play with theplates and endcap

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1999 XL 1200 Sport RX, SE 7500 ignition, SE air filter, DynoJet, K&N, Cone Engineering 2:1 pipe, Storz Steering damper, with 2012 XR1200X perf forks, 3.5 x18" wheels front and rear, Galfer stainless lines, XR1200 4 piston front calipers, 18" Dunlop D404 130/70 and Dunlop trailmax mission 140/80-18 rear XR1200X perf shocks, 19/48 530 chain conversion, Dart Flyscreen, Bosch 480ah LiFePO4
1983 XR-1000S to XR-1000RX Project Build Thread
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5th April 2023
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XL FORUM TEAM MEMBER
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Join Date: Jun 2008
Location: On a big rock in the Florida Straights
Posts: 572 Sportster/Buell Model: XL 1200 S....X Sportster/Buell Year: 1999 Sportster/Buell Model #2: XR-1000 RX Sportster/Buell Year #2: 83 Other Motorcycle Model: SOLD - RZV500R/R1 hybrid Other Motorcycle Year: 1984
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Quote:
Originally Posted by conv90
I made a road test.
Nothing special. I feel it more "soft" , probably with little gas opening the 2000 to 3200 rpm are more effective. But I feel a torque decrease (3700-to 4800-5000) when the other system (all OPEN) start to REALLY SHINE (around 3800 and UP to rev limiter).
Unexpectedly , at 5000 rpm , it start to gain torque again (probably after that torque dip ends, I feel it strong).
I removed it and I made another system with the same device used before BUT with spring loaded cap.
It needs to breath more? the cap will go further out because of RPM/load .
I'm not expecting it works (I'm expecting to loose it on the road...LOL)
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Looks cool a passive device based on exhaust volume ?
Ive seen systems in the intake and exhaust with butterfly valves to vary the effective length of the intake runners and to control the exhaust back pressure based on RPM...
We used to flatten/max the area under the torque curve on the Power valve 2 stroke 500's by making a dyno run with the controller pinned closed and then one pinned open then plot the two curves on top of each other and program the power valve to open over the hole in the curves and raise the exhaust port...
I heal to slow now to want speed I just want torque now LOL
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5th April 2023
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Senior Chief Master Mechanic 2nd Class
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Join Date: Mar 2009
Posts: 1,598 Sportster/Buell Model: 1200 Sportster/Buell Year: 95
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The reality is nobody makes a performance exhaust for a 90”. I’ve had the best luck cutting up an exhaust over building one. Find a theory and work it.
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5th April 2023
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XL FORUM TEAM MEMBER
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Join Date: Oct 2008
Posts: 1,093 Sportster/Buell Model: Sportster Sportster/Buell Year: 1990 Sportster/Buell Model #2: Sportster Sportster/Buell Year #2: 1975 Other Motorcycle Model: Buell S1 W Other Motorcycle Year: 1998
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I made the road test.
Just when on the road i thought: " Damn I found the holy graal!!!!...if this thing will give me the same top end as before, probably I found the right way to follow"..
It has so good low gas opening manners! and it is so quiet!
But, then I discovered that when you open the gas more or you reach some rpm, it needs a more open/free exhaust.
The mid rpm are not so good too.
Yes when you open to 1/2 to 3/4 even WOT the device opens enough, but i do not feel it STRONG like the open exhaust.
Just the time to think the next move in my mind when driving (a softer spring or a bigger plate or a lighter plate or adding more discs under the device - only 2 were installed-), I lost the round plate along with the threaded bar securing all together.
[EDIT] how can I put here a Video?, I have not a Youtube account..[EDIT]
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7th April 2023
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XL FORUM TEAM MEMBER
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Join Date: Oct 2008
Posts: 1,093 Sportster/Buell Model: Sportster Sportster/Buell Year: 1990 Sportster/Buell Model #2: Sportster Sportster/Buell Year #2: 1975 Other Motorcycle Model: Buell S1 W Other Motorcycle Year: 1998
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https://files.fm/u/c3gdrrkan
Before to loose it on the road..
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7th April 2023
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Bike Builder
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Join Date: Apr 2019
Location: 17130 Spain
Posts: 1,885 Sportster/Buell Model: XL 883 ₪ 1275 Sportster/Buell Year: 2006 Other Motorcycle Model: Big Dog K9 Other Motorcycle Year: 2006
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Sounds GOOD!!!!!
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