Do it yourself under tunnel exhaust (sick of searching)

[Grimm]

I see nussing! (Colonel Klink)

 

[Creek]

Hi! Here's my solution for a undertunnel exhaust. It's a Vector header with a small connecting tube to a generic oval shaped carbon bike muffler.

Othervice good, IMHO, but now when considering to moving to a AC float skid, there might be a slight problem fitting the muffler and the new skid together. One solution would be moving the muffler more forward and thus making some little more room for the skid to collapse fully.

 

[FloridaBoy22]

What size is that can? I been thinking about doing mine after reading this thread! I have an MBRP can, and it looks to be about the same size as the one you have.

 

[Creek]

I got it from this British shop, one of those "ready made silencers". I think that the oval is made of 110 mm round carbon tube. Didn't measure the height of the oval, but I guess it's close to 75 - 80 mm.

Good thing is that they make these things up to your tailored order and if you do your homework right, the muffler will fit a Vector header nicely. That being said, I did mix up the diameters, so I needed a sort of a adapter in between

http://www.pjengineering.co.uk/products.php?cat=25

E: the lenght of the muffler is 500mm from frontplate to backplate, 1 3/4 " bore through

 

[Mountaintech]

I see nussing! (Colonel Klink)

That would be Sergeant Schultz! Congrats on the weight loss thus far.

 

[Off Trail Mike]

Hi! Here's my solution for a undertunnel exhaust. It's a Vector header with a small connecting tube to a generic oval shaped carbon bike muffler.

Othervice good, IMHO, but now when considering to moving to a AC float skid, there might be a slight problem fitting the muffler and the new skid together. One solution would be moving the muffler more forward and thus making some little more room for the skid to collapse fully.

Creek:

I am with you....the undertunnel is a Royal PITA, doubly so with the AC skid. My experience is if the muffler is more that 2.5 inches below the top of the tunnel where the opening is, its going to catch the track. I've been thinking about it for a long time and MIGHT finally have a plan that works.

Since you only have a couple of vertical inches below the top of the tunnel to place the muffler, I'm planning to use a raised block off plate similar to the Skinz unit to place the muffler. To get this to work, I intend to use a Vector header and weld on a custom "S" midpipe which raises the muffler enough to clear the track. Next, the blockoff plate will be used to bolt the muffler to, and finally an "S" bend oval tail pipe off the muffler which will get the tailpipe below the tunnel and a quick 90 degree bend allowing it to exit via an cut out on the side of the tunnel(just behind the running boards). This setup also helps me easily add/remove my dB reducer depending on where I am riding. Oh yeah, its all a really, really tight fit.

Still gathering parts/materials right now so hopefully over the next couple of months, I'll get a thread going on the way thru the process.

OTM

 

[Creek]

OTM, yes, that would probably be the only suitable solution to fit both piping and track in tunnel.

I thought about this issue first when fidling with the idea of undertunnel pipe. What got me wrong was the false feeling that the muffler seems to be hanging good 2 - 2.5 inches above idler wheels... never really came to think about the bottoming of the rear skid damper!

Thanks to you guys in AC skid thread, it finally was realized by me too that actually all the room in tunnel will be needed for track in some extreme conditions.

Looking forward to seeing some nice photos of your idea!


Creek

 

[birkebeiner]

Just finished my under tunnel exhaust. All that is left is to polish the tunnel and mount my fuel pack.

What type Skinz tunnel pack is that?? Been looking for one as well for that exact set up..!

 

[2Farnorth]

Just finished my under tunnel exhaust. All that is left is to polish the tunnel and mount my fuel pack.

What type Skinz tunnel pack is that?? Been looking for one as well for that exact set up..!

Nytro Seat Kit and Under Tunnel Exhaust Kit

http://www.skinzprotectivegear.com/snow ... tkits.html

It fits like a glove with the stock seat.

 

[birkebeiner]

Looks good.

Did you get to buy just the pack?

 

[2Farnorth]

Looks good.

Did you get to buy just the pack?

Yep, called Skinz and told them what I wanted and they were more than happy to help me out.

 

[all_4_stroke]

Well it seems none of you have done the same thing I have for under tunnel exhaust, so I will enlighten you. This is about the cheapest method ever! First remove seat, stock muffler and all the brackets, and gas tank. Remove header from nytro. Acquire or borrow an oxy acetylene torch. Heat and bend down the the muffler end of the header pipe so that it no longer protrudes through the tunnel. Re-install header, get a piece of aluminum cut to fill the hole in the tunnel and rivet in place. Next cut off the inlet from the stock muffler, purchase yourself a muffler of your own choice. Hindle makes a low profile 8" muffler that will fit nicely. Once you have your new muffler have a welder weld the old inlet onto the new muffler, this will make a seamless install as far as mating with the header. After that secure the muffler to the tunnel with some sort of support so that it is sturdy as hell. Now moving back up top, re-install seat and gas tank. Mark and cut the heat shield/ seat support so that it does not extend past the rear of the seat. And ta da! Tunnel dump complete. I will try to get some pics up if you guys want, don't have any right now, sorry.

 

[HYFLYR]

Have done many just like stated above^^^. I just cut and weld the collector pipe at the single piece at the correct angle and walla, perfect angle for a under tunnel.

 

[all_4_stroke]

heres some pics

 

[Sledboy04]

I've been running with my under tunnel for 4 years now and have yet to hit the exhaust with my track-here's a breakdown of the costs: Total cost was somewhere about $450. ($40 exhaust header off-e-bay, $80 H20-jet plate, $36 sheetmetal segment, $140 Two Bros exhaust off e-bay, $20 exhaust packing kit, $100 ceramic coating, $15 stainless bolts/clamp, $10 exhaust springs, $5 for exhaust reducer/expander(?) and aluminum block from scrap found in my shop) I did my own welding and machining.