View Full Version : Building your own

11-19-2009, 01:56 PM
I have a good quality tube bender and I am thinking of building my own exhaust system. The bike is an 04 harley sportster 1200 r. What I am thinking of is using the #317-2000 body with the 310-0400 core kit..I am hoping to get the head pipes to an equal length and I am guessing at this time they will be approx 36 inches but I need to do some checking on that..this will be a 2 into 1 system..I have done some shopping and no found just what I am looking for..Any ideas are welcome..


11-19-2009, 02:56 PM
The Universal 3M DirtBike will not flow enough for your application. Take a look at the S/C Standard or any of the other 4" disc Universals;


11-20-2009, 01:17 PM
H'mmm reading the documentation it says the 3 inch is suitable for up to 92 cubic inch or 1.5 liters..since the bike I am working on is 1200cc it seems that the 3 inch would work..please advise..


11-21-2009, 11:00 AM
From my readings here and all over the Web, pipe core diameter is what is critical to flow. The core diameter must either remain constant to the tip of the exhaust muffler or become greater, thus creating a scavenging affect (http://supertrapp.com/resource/faqs.asp#34).

On my 899cc Kawasaki, the mid pipe outlet diameter is 2 3/8." I have a universal Supertrapp with an inlet diameter of 2 1/2" and 4" diffuser slipped over and sealed to it. I alternate between 8 and 9 diffusers to dial the back pressure in to perfection. More here (http://forums.supertrapp.com/showthread.php?t=434#3).

11-23-2009, 08:27 AM
The "hole" in a 3" disc is 1.625", which is smaller than ONE of your primary pipes. The 3" unit may work; however realizing the Full potential of your motor is HIGHLY unlikley.

05-18-2011, 10:06 PM
This one will handle a Sportster motor just fine:


05-20-2011, 09:27 AM
Another popular 'universal' muffler for the XR is the Aluminum Racer Series units.

05-20-2011, 11:25 AM

Thanks Jeff.

Two (2) pounds of difference, right?

6.13 lbs for the 449-2018 steel
4.13 lbs for the 422-20000 aluminum


05-20-2011, 12:00 PM
Correct, alum vs. steel