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osok
03-29-2009, 07:01 PM
I have a set of stock exhaust pipes on my Honda VTX-1800R that look stock on the outside but have been gutted, so they're basically straight pipes with the tail end having a piece of tubing approximately 2.0" ID sticking out the backe end. There seems to be enough pipe where I could design an adapater to hold 12 disc per pipe. Is 12 disc enough to allow free flow and yet quite this bike down. It's not bad on the highway but in town she'll rattle your brains lose. I guess I need to know if I added 20 disc per pipe as I have read about here on the supertrapp homepage to allow full exhaust flow at the end of these pipes will I get the flow I want and get it quite too.

hugger
03-30-2009, 03:48 PM
I have a set of stock exhaust pipes on my Honda VTX-1800R that look stock on the outside but have been gutted, so they're basically straight pipes with the tail end having a piece of tubing approximately 2.0" ID sticking out the backe end. There seems to be enough pipe where I could design an adapater to hold 12 disc per pipe. Is 12 disc enough to allow free flow and yet quite this bike down. It's not bad on the highway but in town she'll rattle your brains lose. I guess I need to know if I added 20 disc per pipe as I have read about here on the supertrapp homepage to allow full exhaust flow at the end of these pipes will I get the flow I want and get it quite too.

The # of discs you use will be dependant on a few things, i.e. humidity, altitude and the state of tune of the motorcycle. At 12 discs, sea level and a stock mc you will have more of your powerband on the bottom end. Adding more discs will move the powerband up, going to 20 discs on a stock VTX will give you more mid to top end power and more sound. Even at 20 discs it is still going to be much quieter than it is now.

osok
04-10-2009, 12:37 PM
I was told by the tech department to start with 18 disc per pipe with a closed cap end. I now have to make adapters to fit the mod that was made to the pipes. Why would anyone want to have supertrap disc with an open caped end. Would the disc even serve a purpose when an open ended pipe?

jwells
04-10-2009, 03:47 PM
The open end cap has a tapered cone with a smaller hole than the ID of the discs, so it is not 'straight thru' the tapers acts to slow the flow down slightly. What you are also doing is effectively 'tuning' the length of the core with the number of discs.

This is not applicable to your bike.

On your application, your goal is to try and make it quieter than what it is now. Obvioulsy we did not test on modified stock mufflers so the suggestion to start with 18 discs is going to be about as free flowing as can be, from there you will have to 'play' with it and adjust down to your desired results.