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CHEAP free-flow exhaust can

2043 Views 5 Replies 3 Participants Last post by  Scalku
I bought a Husky a few months ago and have been thoroughly been enjoying it in the time i have owned this wonderful machine.

*note, if not looking at how to do this yourself, just skip to the pictures*

I am a college student and haven't been working much because my place of employment caught fire and i have only been getting my paycheck from my boss' insurance (tips are a fairly big portion of my income, insert stripper jokes here), so I have been a little tighter on cash than normal... and I had to set up my bike a little bit more to my tastes (1 1/8 bar mounts, tall fatbars, sm hanguards, sliders etc), as well as fix other parts on this bike and myself after I did pulled my squid muscle and did a superman into a car going ~40mph. I have been rather sick of living with the 10 foot long and restricted stock exhaust, so while i wait for the pennies to trickle into my account to buy a full leo vince system... I decided to chop and gut my can! Another reason why I wanted to modify this exhaust before i got a new full system is that my HI-temp mx boot plastic was melting onto the muffler when i would do stand up wheelies on the passenger pegs. My gf had to be very careful to not let her inner thigh touch this muffler at any time just because of how the heat was retained in the restriction baffles inside the muffler, hopefully gutting it will keep it much cooler, because this exhaust was a serious hazard with how insanely hot this thing would get. hotter than the headers on some other bikes i have had.

First I took off the muffler and drilled out all the rivets.
The muffler is a big aluminum tube which acts as a sleeve with mounting brackets. Steel inserts with all the baffles and various restrictors thrown in there to make "chambers" for the exhaust. a definite no-go when you want free-flow.
The end cap comes off in a small piece and the header-side insert is what fills most of the submarine-like aluminum muffler sleeve. after ram-rodding the big side out, i trimmed it down quite a bit (so it was a couple inches longer than the end cap).
I then took my dremel to the orifice in the endcap and removed the 1" tube that ALL of the exhaust had to go through, all while retaining the ever so lovely husky "H"gunsight logo. I then removed all the steel wool behind a metal screen.
I took my sawzall and cut down the inner steel baffle tube (header side) so there were no more things to restrict the flow of gasses. There was a corrugated metal fixture inside the tube right where the header attaches to the insert. Think of a 2-3" strip of cardboard, rolled up into a cylinder, and then you look down the side of it, and can see light through the corrugated cardboard, that's what the exhaust had to go through. so i hammered that out with a crowbar as a chisel.
i then took my sawzall to the aluminum sleeve and cut it down 7-8 inches (so it ends an inch or 2 past the mounting brackets)
got my 4" belt sander, flipped it upside down, and sanded down the jagged edge of the tube until it was all smooth and level. I then sanded the melted boot plastic off of the tube 2.5"x8" with the belt sander, and then went over everything with 320grit and then 600 grit sandpaper to smooth it all out. i may go back with some 1-2k grit paper if i want a full polished can.
I drilled some holes to rivet the inserts back into place, and riveted them. The old rivet holes on the header side were worn out and needed re-machining anyway so i decided to double up on rivets and place new ones further into the sleeve.

The original exhaust:

The final product:

gunsight logo still there :thumbup:

still a little muddy from yesterday

and now I can ride around like this:

overall results:
7-8" shorter muffler
2-3 lbs of material removed from the exhaust
Hopefully runs much cooler than before- safety hazard removed
no-more melted boot poo-looking stains on the muffler

noise is about equal to that of my 450 with a big-gun evo race series (spark arrested) system, maybe a little quieter, have to ride to find that out. I was surprised to see how well the exhaust sounded when i fired my bike up with no muffler on at all. I couldnt hear much of the typical hollow backpressure sound which one would normally hear on a bike with no muffler.

Hope this helps to anyone looking to uncork the muffler on their husky!

Now I can focus on getting a new supersprox sprocket setup to properly gear the bike! :clap:
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Solid write up. Any noticeable increase in power?
Looks familiar... x2

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Solid write up. Any noticeable increase in power?
huge noticable increase. i am sure there is a power increase down way low, but that was the torqu-iest part of the rpm range before i gutted the can, so i can't even notice a huge difference with the gearing i have. it doesn't hesitate as much when i go on the throttle hard at lower rpms (2750ish) like it would before.
mid range has an increase in the pull, and I would gut the can if it were just for this increase in mid range
upper rpms - before when you would rev out the bike it would just lose ALL power getting into the higher revs, and I thought it was just a characteristic from the cams on the bike... turns out that this bike keeps pulling strong up top. I would say it's power curve up top is fairly comprable to the upper rpms on an mx bike. It keeps pulling, and you feel it there, but you can notice it taper off just before the rev limiter kicks in

Looks familiar... x2

you should shorten yours though! looks great, saves weight (especially with 2!), and lowers your center of gravity!

The can is no longer a safety hazard regarding the heat issue. While it is still hot, and you don't want to hold your hand there, I am not worried about instantly burning myself (or my gf's thigh) through a pair of jeans instantly.
This may be a figment of my imagination, but in a hard lean (parking lot riding, kart track style), when the rear would start letting go (apex--->exit of corner) while i was on the gas in a far lean sometimes the rear would want to bounce up and down, and there being less weight from the can and sticking out less seemed to settle the rear down a TINY but still noticable bit.

Winter mods planned for the bike: JD jet kit, replace the air filter (have one, but dealer shipped me the cheap one and charged me for the $$$ one... :rolleyes:), chop some holes in the airbox cover, 5" rear rim, Powdercoat rims hubs (and spokes?), and if i start making carbon fiber parts like I want to... Start making some candy for my bikes :bannana:
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You will like the JD. I waited to gut my cans until I got mine installed so I wouldn't be running obnoxiously lean.

Also, did you just completely gut your can, with no perforated core or packing?

I welded in a short exit tube and threw in some 1.75" perf core and muffler packing, so at idle it's not much louder than stock, and only gets loud when you're on it hard, but doesn't resrict the flow.

I thought about shortening them down a few inches, and may do it when they need repacked, we'll see...

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Correct, nothing is in my can anymore. I didn't make my exit hole as big as your exit pipe so it restricts things just a TINY bit so it evens out pressure waves and cancels out any backpressure. Since it is a straight pipe it has no spark arrestor, and with all the USFS land that I constantly ride... I definitely need to have one of those. If I need to add a screen type spark arrestor, I will, but I was planning on getting a lighter titanium Leo Vince system so I can have the weight savings, power gains, and spark arrestor w/ a removable sound baffle.

Also, I don't have a jet kit because it is factory jetted (lean) for sea level. I am at 5k ft in altitude and higher on my rides, so with this can and an opened airbox it should be fairly well jetted for this altitude. Just a little rich. But with cold weather... Maybe its right on?
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