6th gen cat gut---how to---pic intensive

First let me start by thanking "Oh Whell" for providing lots of pictures during his cat gut. I intend to do the same and give a few extra pointers. Without his pictures, I would have had a lot tougher time deciding exactly where to begin cutting.


First, a picture of what you are dealing with, easiest access is at the bottom, top has a heat shield that is welded in place, no reason to mess with it
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Next, I used a sharpie to trace out my cuts, mine were guesses but were just about dead on, rear cut is 2.25" from the shorter plate of the center stand stop, front cut is 1" from where the headers are welded to the collector. It is fairly easy to see the outline of the honeycombs from the outside. Don't get too hung up on measuring the cuts. guesstimate from my pics.
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Here is the first cut. Go slow, the cleaner the cuts, the easier the plate will be to weld back on. cut all the way down the the welds near the heat shield.
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Second cut, made right where it starts to slope down, a little tricky but again, be patient, I had to switch cutoff wheels at this point.
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Here is a detail of where you need to cut down to on both sides and on both cuts.
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Now we follow above the weld across to join both cuts. Do this on both sides.
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Here is the final step before you will get to see the honeycombs. Grind the two welds that are visible. You will have to grind them down completely until you see the two different pieces of metal. Once you think you ground enough, try prying the piece away, it should feel fairly loose at this point.
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Here are two pictures of the plate off after you have ground the welds.
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Once you have the plate off you need to make two cuts, one on each honeycomb, after you do this the "bridge" in the middle will come off and the two honeycombs will no longer be joined, they should be able to move a little.
Forgot to take a picture of this step....sorry.

Two more cuts will be made at this point. One on each side, this will remove a little more of the "band" that goes around the two honeycombs. After you make the cut, you can hit the weld with a chisel and break it. If you do this on each side, the honeycombs will be free.
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Here is what you are left with once you remove both honeycombs.
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The plate should fit back on nicely, ready for welding.
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Now we are ready to weld it all back up.

First I cut a piece of stainless to fill the two holes. I then used clamps to bend it to shape on the inside.
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Now I cleaned up all 4 sides and put it in place ready to weld it up...tack first. Let me warn you, I am not a welder. I took a few welding courses and used to be decent at it but that was also using a very nice miller mig welder. I used mild steel wire and a 75/25 argon/co2 mix. I should have used 100% argon and stainless filler, hence the ugly welds. I may grind them down and get the headers jet hot coated.

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What was the increased performance criteria that you needed to obtain in order to justify removing pollution controls?

[image: View Post]swimmer, on 02 December 2009 - 08:24 PM, said:

What was the increased performance criteria that you needed to obtain in order to justify removing pollution controls?

With a BMC filter, PCIII, gutted cat, and exhaust, I am hoping for somewhere around a 10HP increase but expecting a little less. We shall see

BTW, I realize I removed a pollution control device, but would you be asking someone that question who put on a set of 98-99 headers or motads, delkevics? I've never owned a bike with a cat before this. While i try to be as friendly to the environment as possible, I'm not sure this is a huge issue.

Do you have your aftermarket exhaust yet?  Which brand did you get?  Do you plan to dyno your bike at all?  Seems like that would be a pretty free-flowing set up.

I have a 2 brother stash system on the way but I also have two sets of stock mufflers, 1 of which I did a full gut to. I like the sound of the gutted stock. I may sell the 2 brothers, I will have to compare the sound/performance. I think the stock exhaust is also the best looking since it fills in all of the gaps.

Looks pretty similar to my 5th Gen Cat Gut from three years ago.  I guess that "How To" is gone.

Cut the heat shields off:
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Mark your cut:
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Cut it open:
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Getting the honeycombs out is a beeeoch.  Lots of hammering and cussing and cutting:
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Don't have any pictures of my gas welding work with brazing rod, but here's the finished product after JetHotting. Notice the plugs in the O2 bung holes....just some items I picked up at the local Auto Zone--oil drain plugs or something I found that fits.  It's a standard metric thread, no biggie.
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Since doing this gut work, I changed to a set of 98 pipes (that I also JetHotted) and sold these 2000 pipes to a VFRD member.

[image: View Post]Trace, on 02 December 2009 - 09:46 PM, said:

Looks pretty similar to my 5th Gen Cat Gut from three years ago.  I guess that "How To" is gone.

Cut the heat shields off:
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Mark your cut:
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Cut it open:
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Getting the honeycombs out is a beeeoch.  Lots of hammering and cussing and cutting:
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Don't have any pictures of my gas welding work with brazing rod, but here's the finished product after JetHotting. Notice the plugs in the O2 bung holes....just some items I picked up at the local Auto Zone--oil drain plugs or something I found that fits.  It's a standard metric thread, no biggie.
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Since doing this gut work, I changed to a set of 98 pipes (that I also JetHotted) and sold these 2000 pipes to a VFRD member.

Damn trace, those chrome pipes look pretty darn good. How did you like the gutted headers? Did they sound/perform decently? How did the jethot hold up?

[image: View Post]Trace, on 02 December 2009 - 09:46 PM, said:

Looks pretty similar to my 5th Gen Cat Gut from three years ago.  I guess that "How To" is gone.

Cut the heat shields off:
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Mark your cut:
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Cut it open:
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Getting the honeycombs out is a beeeoch.  Lots of hammering and cussing and cutting:
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Don't have any pictures of my gas welding work with brazing rod, but here's the finished product after JetHotting. Notice the plugs in the O2 bung holes....just some items I picked up at the local Auto Zone--oil drain plugs or something I found that fits.  It's a standard metric thread, no biggie.
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Since doing this gut work, I changed to a set of 98 pipes (that I also JetHotted) and sold these 2000 pipes to a VFRD member.


so did you notice any difference between the gutted headers and the 98-99s?
ie sound and performance?

...not very green...















LOL, ROFL!!!!!

What color should I jet hot coat my headers after I grind down my crappy welds?

[image: View Post]pjm204, on 02 December 2009 - 09:56 PM, said:

Damn trace, those chrome pipes look pretty darn good. How did you like the gutted headers? Did they sound/perform decently? How did the jethot hold up?

[image: View Post]CandyRedRC46, on 02 December 2009 - 10:04 PM, said:

so did you notice any difference between the gutted headers and the 98-99s?
ie sound and performance?

The honeycomb is very open and appears to be free-flowing to my mechanical engineer's eyes, and in all honesty the bike didn't suddenly become an RC51 or a Gixxer after the gutting....very little (if any) change.  I believe the 98 headers had a better overall effect across the powerband than the gutting.  Gutting did change the sound (a little deeper) but that has a lot to do with my hard-packed Erion muffler.  I doubt you could tell much of a diff with stock mufflers, either 5 or 6th Gens.

One good thing about the gutting is that you get rid of about 8 lbs of metal down there, counting the heat shield and the honeycomb.   :fing02:

In general, I think 98 pipes and some good PowerCommander work gives you the most bang for your buck.  But if I had it all to do over again, I'd start with my forks and shock and tapered steering head bearings and leave the engine alone.   :blink:

JetHot holds up okay.  They get coated with baked-on road grime from dirty water splash, but the main two pipes that snake behind the fairing always look great.  JetHot is an interesting liquid-silvery color.  It looks awful agains chrome, which is why I disassembled my Erion and sent the pipes and end cap to JetHot, too.  
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After removing the honeycomb would there be any benefit to add a baffle between the chamber now that it is a big open cavity?

Also, losing weight on a 6th would be nice, but removing weight down low I would think to be bad as it raises the CG potentially make the bike more top heavy?

Any idea what it cost for the Jet-Hot?

[image: View Post]JHKolb, on 03 December 2009 - 11:50 AM, said:

After removing the honeycomb would there be any benefit to add a baffle between the chamber now that it is a big open cavity?

Also, losing weight on a 6th would be nice, but removing weight down low I would think to be bad as it raises the CG potentially make the bike more top heavy?

Any idea what it cost for the Jet-Hot?

No, there's no way to know if some baffle would help or hurt exhaust flow.  And if it did help, it might be worth 1/4 hp.  Or it might hurt it 5 hp.  There's just no way of kowning, because you can't begin to imagine what the flow in that canister might look like at 11,000 rpm.  I just left it alone and allowed the exhaust to go where it wanted to....out the tailpipe!   :blink:

As for weight, low or high....we're talking about .018 of the bike's total weight [8 divided by 450], so it's not like it suddenly handles like a new 600RR.  The Viffer is a heavy pig no matter where the weight is located.    It's a great sport-touring machine...but it's simply NOT a racebike no matter what you do to it.  

My first pipes were $180 a few years ago, plus about 30 for shipping to and from.  But they changed and combined ownership and prices went up a bit.  Figure approximately $220-260, give or take, considering shipping and all.