How-To: DIY Shorty Exhaust

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dem0nk1d
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How-To: DIY Shorty Exhaust

Post by dem0nk1d »

So here we go again one of dem0nk1d's epic DIY with massive photos for detail. Better go grab a cold one!

Tools:
MIG Welder
Angle Grinder
Cut off wheel
Flapping Disc
Blue tape
Safety Glasses


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Decided I'll make the cut at the end cap behind the weld, and start from that weld line to 7"

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Sharpied in the 7" mark
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All taped up for guides
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And so it begins!
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I had to section out the rear of the exhaust because the inside tubes go into the end baffle
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Baffle is spot welded into the out exhaust shielding, and i thought it was going to be easy
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Has to finish the rest of the pipe off with a sawzall this basically released the rear section of the exhaust and reviled the CAT
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Mayhem!
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Cat materiel is pressed into the inner tube, the main header tube i guess you could say. I used a number of drill bits to loosen this stuff up.
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Perfectly gutted!
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Main plastic shielding mount has to go!
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Take your cutoff wheel and get close ass possible then work at the rest of the metal with the flapping disc
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Try to get the cap matted up with the other half as perfect as possible this will make welding things back together much easier
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I then went back over the welds and grinded them down and tried as best as possible to smooth them into the pipe
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Mounted and ready to go!

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So the main question is how does it sound? If you imagine or have ever been to a destruction derby, it's like that! I'll try to post a video later, but even the audio can't compare to the real thing. I'll be testing some other designs for the internal baffling situation to make it A LOT more quite! More or less going with that perforated steel. We will see how long it takes for me to get rolled by the cops. I have feeling it will be soon.
Mgalutia88
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Re: DIY Shorty Exhaust

Post by Mgalutia88 »

What did it do to performance? How did it affect the power band?
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Slickvic
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Re: DIY Shorty Exhaust

Post by Slickvic »

dem0nk1d, I always look forward to your DIY postings. Nice work.

Thanx again.
Previous - 1986 Honda Elite 250, 2007 Ninja 500r, 2013 Honda PCX-150
Current - 2015 Honda CBR650F :o
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dem0nk1d
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Re: DIY Shorty Exhaust

Post by dem0nk1d »

Mgalutia88 wrote:What did it do to performance? How did it affect the power band?
Seems like when i get on it, at Wide Open Throttle the speedo needle moves very fluid. But the real test is when i go to work today for inventory. I'll be hitting the freeway.
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dem0nk1d
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Re: DIY Shorty Exhaust

Post by dem0nk1d »

Conclusion is that the pipe is too free flowing and doesn’t make enough back pressure at high RPM. Other than looking better, it’s extremely loud. I’ll be creating some kind of baffle during the week to come. However I did have a few people take photos of me on the freeway ride to work. LOL…
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kramnala58
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Re: DIY Shorty Exhaust

Post by kramnala58 »

dem0nk1d wrote:However I did have a few people take photos of me on the freeway ride to work. LOL…
If you were wearing the crown I can understand whey they were taking the photos. ;) :lol:
2010 Honda PCX 125 in Thailand (White) - "White Lightning" Sold in Sept 2017 :(
2009 Yamaha Majesty YP400 in USA (Metalic Titanium) - "The Throne" Sold in June 2020 :(
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dem0nk1d
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Re: DIY Shorty Exhaust

Post by dem0nk1d »

Video Clip!

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Re: DIY Shorty Exhaust

Post by Urbanfreestyle »

I really want to hear this thing!
Honda PCX 125 ESP (Black)
Power:11.7 hp @8500 rpm, Torque:12Nm @5000rpm
Mods: LED sidelights, Yoshimura Exhaust

DEAD: 2013 Piaggio Typhoon 4 stroke 125cc (Black)
Power:9.65 HP @8500 rpm, Torque:8.2Nm @7500 rpm
Mods: Malossi Red foam filter, Hex LED Sidelights, Xenon headlights, USB charging port
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Re: DIY Shorty Exhaust

Post by chucktuna »

You crazy man!

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Too many scoots..... 12 or so I think .
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dem0nk1d
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Re: DIY Shorty Exhaust

Post by dem0nk1d »

Okay second round, lets split this BISH open AGAIN! (Facepalm)

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Objective is to remove the main exhaust tube as far into the muffler as possible
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Okay this was the most difficult part trying to figure how to get inside the pipe to cut the pipe as far back as possible. My solution was using a dremel to get things started, tin snips, and time
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Slight bevel on the can and a clean surface to weld to
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Now time to create the baffle. With the left over piece of pipe i used paper to give me a pretty accurate messurement of the OD of the pipe. This way we can slide the baffle over the smaller stub in the muffler.
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All marked up... Aprox 5.5 inches from memory Using the paper as a template to transfer into the Preforated Steel Sheet
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Using the old piece of pipe to help shape the handmade baffle
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Review:

Basically I didn't stuff the muffler with fiberglass packing, as the muffler is all welded up. But I did add the perforated steel line, and even add it on the exit hole to reduce the chance of sparks. So in the end result going with prototype 2 what do I think of it? It’s registering at 86 DB at idle, isn’t raspy as it was purely gutted. I’ve gained some back pressure, and it’s tolerable now. Hell this morning on the way to work the CHP passed me and didn’t even look at me. So all in all it passed the test!
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Re: DIY Shorty Exhaust

Post by maddiedog »

Awesome mod. Way, WAY cheaper than getting one of the coffee can-looking exhausts and probably just as effective.

What type of welder do you have, and any advice for someone who is interested in learning how to weld?
Currently ride: 2011 Honda PCX 125 - Upgraded windshield and seat, keeping this one mostly stock
Previously rides: 2005 V-Strom DL650, 1974 Vespa Ciao, 2011 Honda PCX 170 (tons of mods - takegawa 170cc big bore kit, gears, etc), 1996 Honda Nighthawk 250, 1987 Honda Spree, 2000 KTM 125SX, 2003 Honda Silverwing, 2007 Genuine Buddy 125, 1998 Honda PC800, 2008 Buddy 125 (white), 2008 Buddy 125 (red), 2001 Honda Reflex, 1987 Honda Elite, 1988 Honda Spree, 2007 Yamaha Vino, 2007 Honda Metro, 2x 125cc pure-chinesium dirt bikes
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dem0nk1d
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Re: DIY Shorty Exhaust

Post by dem0nk1d »

maddiedog,

I’m a full time rookie, part time fabricator. Actually the whole story with me and the wife moving into the house, was that the garage is mine. Then she gave me a 2k limit on what I wanted to buy. This was back in May of this year. To make a long story short. I bought a Miller MVP 211 Dual Voltage mig welder. I figured that ever post I read said go the biggest you can guy.

I got the welder for 850 used (Retail 1200-1300 not including tax) on Craigslist, and came with regulators. I still needed to purchase a bottle, which I got the biggest bottle I could which is the 120-125cfm bottle. Here’s the deal with Argon/Co2 mix gas. It cost a fraction more to fill a 120-125 bottle than an 80 bottle. I do mean a fraction like a whole 10 bucks, for almost double the amount of gas. You want to weld with gas. Also here in California, the bigger bottles are Buyer OWNED. So you can find a used one like I did for 120 bucks. Also the great thing is it was out of date, and would have need Hydro Testing… But had a westair sticker on it. I brought it back to them and they just exchanged it for the price of a fill 88 bucks. A new bottle that size is around 240 bucks, not including gas

So anyhow I’m going on a tangent… Depending on what you want weld, it depends on the machine. I think you can get away with most light duty work with a 130amp 110/120v box. You’ll need to use a 20amp breaker and line. I wired mine directly to a single 120v 20amp outlet. Then next to that is my 240v outlet. 240v machine would blow holes through sheet metal.

Other than that I’m just learning. This was actually my first real mig welding project. Anymore question I can answer when I get home.

Peace! Leaving work!!!! PCX is waiting for me as we speak…


Go with a name brand Mig welder too, I've made the mistake in the past and tried the HF box... Man did that suck..
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Re: DIY Shorty Exhaust

Post by Urbanfreestyle »

If you need anyone to 'test' out the mound jot me down!
Honda PCX 125 ESP (Black)
Power:11.7 hp @8500 rpm, Torque:12Nm @5000rpm
Mods: LED sidelights, Yoshimura Exhaust

DEAD: 2013 Piaggio Typhoon 4 stroke 125cc (Black)
Power:9.65 HP @8500 rpm, Torque:8.2Nm @7500 rpm
Mods: Malossi Red foam filter, Hex LED Sidelights, Xenon headlights, USB charging port
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dem0nk1d
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Re: DIY Shorty Exhaust

Post by dem0nk1d »

maddiedog,

oh and go with gas, flux core welding is for welding outside in the elements. think farm life!
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Re: DIY Shorty Exhaust

Post by dasshreddar »

Hey maddiedog,
If it helps, I just use a Lincoln wire feed welder(home depot $400) non gas, 110v...
works for all my household and scooter needs :)
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pcxpower
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Re: DIY Shorty Exhaust

Post by pcxpower »

Good job!! I wish I could weld like that... (I have a stick welder ;) )
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2015 Honda PCX 125
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Re: DIY Shorty Exhaust

Post by WORFAB »

htp 221dv tig welder ;) ... I did the same thing to my ruckus muffler but left some of the baffling in it.
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Re: DIY Shorty Exhaust

Post by supermattyp »

Ever give any thought to stretching out some steel wool and stuffing it around the mesh section? I've had to use steel wool in automotive mufflers before and it worked well. Not sure how such a small engine would respond to it though.

Great write-up and pics.
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Re: How-To: DIY Shorty Exhaust

Post by chicaboo »

I'm bumping this for the exhaust hole drilling lovers out there. :P
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Re: How-To: DIY Shorty Exhaust

Post by easyrider »

I love doing projects like that. Too often however the results are usually negligible and more costly than buying ready made. Great job, but wondering about the final result. Were you trying to gain HP , noise, weight difference.. What ?? and did you succeed in your final outcome?
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