HarleyTechTalk

I have two questions about Touring 2-1-2 exhausts. 

1)  I'm looking at two aftermarket headpipes.  Both are marketed as using the original heat shields so I'm assuming both pipes have the same length runners as stock.  I'm guessing there's something in the collector that's performing some magic?  So, what exactly are these pipes doing that the stock decatted pipe isn't doing? 

2)  Are the benefits/gains of one of these aftermarket headpipes enough to justify the cost?  Assuming they are used on a simple Stage 1 or 2 set up?

larger diameter head pipes
stepped diameter head pipes
proprietary collector design

to name a few

Taking the cat out does not reduce heat by much, if any.  Power gain is minimal. Better use of that money would be to put it toward a proper head pipe and tune.

O2 sensor operation on a decatted pipe may not be as good as a better pipe.


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Quote from: Hossamania on September 21, 2016, 11:26:51 AM
Taking the cat out does not reduce heat by much, if any.  Power gain is minimal. Better use of that money would be to put it toward a proper head pipe and tune.

Quote from: harpwrench on September 21, 2016, 12:50:11 PM
O2 sensor operation on a decatted pipe may not be as good as a better pipe.

  o2 sensor crosstalk

A top brand X pipe would be my first choice but when a guy is on a budget, I've had good luck with catless stock head pipes on several different combo's.

Heat will be the same with a de-catted pipe as it will be with a good 2-1-2, the tune will dictate that aspect, as well as the O2 sensor operation.

Quote from: UltraNutZ on September 21, 2016, 01:03:28 PM

Quote from: Hossamania on September 21, 2016, 11:26:51 AM
Taking the cat out does not reduce heat by much, if any.  Power gain is minimal. Better use of that money would be to put it toward a proper head pipe and tune.

Do you a source that backs up your crosstalk theory? 

Quote from: harpwrench on September 21, 2016, 12:50:11 PM
O2 sensor operation on a decatted pipe may not be as good as a better pipe.

  o2 sensor crosstalk

Guys, everything be said so far is the same marketing hype that the manufacturers are saying.  I was hoping some exhaust guys would jump in here and give their perspective.

Im interested in some exhaust theory that explains what these aftermarket headpipes are doing that justifies 500 bucks.

Have you checked with Fuel Moto? I thought they had one for around $300, been a while since I checked.

Quote from: 07heri on September 21, 2016, 04:33:27 PM
Guys, everything be said so far is the same marketing hype that the manufacturers are saying.  I was hoping some exhaust guys would jump in here and give their perspective.

Im interested in some exhaust theory that explains what these aftermarket headpipes are doing that justifies 500 bucks.

I have never seen a back to back test that showed the aftermarket head pipe out performing the de-catted  stock head pipe on any stage on or stage two build.

Quote from: 07heri on September 21, 2016, 04:33:27 PM
Guys, everything be said so far is the same marketing hype that the manufacturers are saying.  I was hoping some exhaust guys would jump in here and give their perspective.

Im interested in some exhaust theory that explains what these aftermarket headpipes are doing that justifies 500 bucks.

Best Bang for the buck, IMO $299 @ Exchange rate
http://fullsac.com/product/fullsac-sportpipe/

Quote from: 1FSTRK on September 21, 2016, 04:39:44 PM

Quote from: 07heri on September 21, 2016, 04:33:27 PM
Guys, everything be said so far is the same marketing hype that the manufacturers are saying.  I was hoping some exhaust guys would jump in here and give their perspective.

Im interested in some exhaust theory that explains what these aftermarket headpipes are doing that justifies 500 bucks.

I have never seen a back to back test that showed the aftermarket head pipe out performing the de-catted  stock head pipe on any stage on or stage two build.

I agree Eric.
Here are two 107 builds I tuned that were very close, ported heads, same cams, same compression, both tuned in similar conditions one with a catless stock head pipe and one with a Fullsac X pipe.

This one with the stock pipe.
http://harleytechtalk.com/htt/index.php/topic,89806.0.html

This one with the Fullsac.
http://harleytechtalk.com/htt/index.php/topic,89204.0.html

Is the part throttle response comparable, and do you need to open loop any problem areas that might trip up a DIY v-tuner (when using stock cams)?


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Quote from: 1FSTRK on September 21, 2016, 04:39:44 PM

Quote from: 07heri on September 21, 2016, 04:33:27 PM
Guys, everything be said so far is the same marketing hype that the manufacturers are saying.  I was hoping some exhaust guys would jump in here and give their perspective.

Im interested in some exhaust theory that explains what these aftermarket headpipes are doing that justifies 500 bucks.

I have never seen a back to back test that showed the aftermarket head pipe out performing the de-catted  stock head pipe on any stage on or stage two build.

  Save your money.

Rush has a pipe for under the stock shields, not crazy about the fitment but it does work well.  Bassani has one for under the heat shields and if you check out Dennis Kirk there is an X pipe produced by Hellbent that works very well. As for the best value it's hands down this one from Danmoto  https://www.dan-moto.com/DM_US/touring-wholesale-18_186_190.html  I have used them and the shields fit better than the pipes that cost twice the amount and the performance is on par with the best of them

No matter what you guys might think I have seen built and tuned enough bikes to know that the stock decatted pipe will NOT be on par with a good x pipe once cams are installed. If you do feel the need to use the decat at the very least tack a 2 inch long piece of pipe in the chamber before you weld it back up effectively making the headpipes a tad longer and eliminatingg the cross talk problem

Quote from: BVHOG on September 21, 2016, 06:47:41 PM
Rush has a pipe for under the stock shields, not crazy about the fitment but it does work well.  Bassani has one for under the heat shields and if you check out Dennis Kirk there is an X pipe produced by Hellbent that works very well. As for the best value it's hands down this one from Danmoto  https://www.dan-moto.com/DM_US/touring-wholesale-18_186_190.html  I have used them and the shields fit better than the pipes that cost twice the amount and the performance is on par with the best of them

That's the issue I've had with the last two FullSac DX's....OCD won't let it happen again!

Quote from: BVHOG on September 21, 2016, 06:51:50 PM
No matter what you guys might think I have seen built and tuned enough bikes to know that the stock decatted pipe will NOT be on par with a good x pipe once cams are installed. If you do feel the need to use the decat at the very least tack a 2 inch long piece of pipe in the chamber before you weld it back up effectively making the headpipes a tad longer and eliminatingg the cross talk problem

Do you have some numbers to back it up? 

Quote from: BVHOG on September 21, 2016, 06:47:41 PM
Rush has a pipe for under the stock shields, not crazy about the fitment but it does work well.  Bassani has one for under the heat shields and if you check out Dennis Kirk there is an X pipe produced by Hellbent that works very well. As for the best value it's hands down this one from Danmoto  https://www.dan-moto.com/DM_US/touring-wholesale-18_186_190.html  I have used them and the shields fit better than the pipes that cost twice the amount and the performance is on par with the best of them

Know nothing of the bikeman pipes but the bassani works well...better than most even bassani thought it would and the dan moto works pretty good

  Not sure Bob has to back up what he is stating ...he tunes ...professionally ....a ton of bikes from mild to pretty wild

   a good headpipe doesnt have to cost $600

Quote from: 07heri on September 25, 2016, 03:12:21 PM

Quote from: BVHOG on September 21, 2016, 06:51:50 PM
No matter what you guys might think I have seen built and tuned enough bikes to know that the stock decatted pipe will NOT be on par with a good x pipe once cams are installed. If you do feel the need to use the decat at the very least tack a 2 inch long piece of pipe in the chamber before you weld it back up effectively making the headpipes a tad longer and eliminatingg the cross talk problem

Do you have some numbers to back it up?

Here is one. Nothing changed but pipe. Both tuned

Approx 6 HP between 2,500 and 3,500 ... that's worth having for a few dollars cut and welding.

Quote from: BVHOG on September 21, 2016, 06:51:50 PMIf you do feel the need to use the decat at the very least tack a 2 inch long piece of pipe in the chamber before you weld it back up effectively making the headpipes a tad longer and eliminatingg the cross talk problem

Personally, I don't how the X-pipes would work well. It seems a bit much to ask the gases to play like Scalextric cars. I'm pretty sure something else is going on inside there, e.g. gases colliding, being sheered and going down both pipes. I might be wrong but I'd say it's mostly marketing. I think it looks good, but it's still marketing.

I'm a cheap ass. I'm about to de-cat a stock header and was going to do what you said and a bit more.

My line of thought is to make two half cuts at either end, one at either side, and then split down the middle in a kind of Z-shape. Then fit extension pipes in both halfs with a reasonable curve/opening at the end of the rear one to combine the flows.

I cannot see that it will be really much difference at all from some of the marketed products with long headers. Nor that it will even require any great skill to do well.

I guess that I can probably cut the excess cross over pipe to get the curve I want ... but it's work in progress at present.

Quote from: BVHOG on September 21, 2016, 06:51:50 PM
No matter what you guys might think I have seen built and tuned enough bikes to know that the stock decatted pipe will NOT be on par with a good x pipe once cams are installed. If you do feel the need to use the decat at the very least tack a 2 inch long piece of pipe in the chamber before you weld it back up effectively making the headpipes a tad longer and eliminatingg the cross talk problem

I'm thinking it's also a loss of speed/pressure issue as the gases expand into that big, empty chamber.

Quote from: lonewolf on September 26, 2016, 07:43:20 AM

Quote from: 07heri on September 25, 2016, 03:12:21 PM

Quote from: BVHOG on September 21, 2016, 06:51:50 PM
No matter what you guys might think I have seen built and tuned enough bikes to know that the stock decatted pipe will NOT be on par with a good x pipe once cams are installed. If you do feel the need to use the decat at the very least tack a 2 inch long piece of pipe in the chamber before you weld it back up effectively making the headpipes a tad longer and eliminatingg the cross talk problem

Do you have some numbers to back it up?

Here is one. Nothing changed but pipe. Both tuned

Thanks for posting, that is the first sheet that I have seen posted that shows an increase. Could you give us the rest of the specs on the bike, year, CI. mufflers, cams, air cleaner.  Seems odd it helped both lower and upper rpm and flattened the middle.

Here's another one.  I went from the stock header with cat to FuelMoto stainless/ceramic pipe.  Nothing else was changed.