Gutt'n the Goat Belly

[rlfaubion]

I just bought a new set of stock duals with the catalytic converter for my '06 Nad. I will store it for the day when California clamps down on modified exhaust. You can count on that happening sometime.

Now I'd like to drill out the Goat Belly. Has anyone done this as opposed to Gadgets gutt'n procedure requiring cutting it in half?

If so, what size drill bit?
did you remove the belly to drill?
What did it do to performance?
What did it do to the sound?
Any pitfalls to be aware of?

Just a note - I've already punched through two baffles and removed the silencers.

Thanks for the help.......

[tomk]

Valdez,

I had the same concerns as you about CA and being able to return my bike to stock in a hurry. That's one of the reasons why I didn't modify the stock exhaust that came with my 06, I saved it and put on the V&H baggers.

The other reasons had to do with performance. Ever since I was a kid into hot rods and dirt bikes, intake and exhaust flow was a major concern since the way to make added horsepower was to get the air in and out in a hurry. The more air in and out, the more hp you could make.

The Nad's exhaust is not a true dual exhaust system. It's a 2 into 1 into 2. The goats belly is simply a canister where two incoming pipes dump the flowing exhaust gas from the cylinders into a container and two exiting pipes on the other side of the canister allow the gasses to escape. When in the goats belly, the exhaust is not flowing smoothly through a tube, its just dumped into a can and needs to find a way out. The exiting gas follows the path of least resistance but is not smoothly directed.

I think BD can probably explain the concept much better but than me but power increases with the goats belly still in the exhaust system will be minimal if at all. The sound increases because the honeycombed baffle in the goats belly is removed but the exhaust gas is not allowed to exit any faster.

[ringadingh]

There was a guy somewhere who made a bypass pipe to replace the goatsbelly, you could switch it back if you had to quite easily. You may be able to find more info on Gadgets site as I cant remember for certain where I saw it originally.

[rlfaubion]

Tomk,

As you know, after-market pipes cost around $450. I have those goodies on my Classic, but I’m trying to do this without as much expense. I’ve paid $150 for the stock system.

You've pointed out I shouldn't expect to get additional performance (HP) by removing the inners of the converter, but I was just curious if I might get any, and of course, I’d take what I could, but that’s not a deterrent to me doing this project.

I appreciated your clear explanation as to gaining additional performance by way of air in – air out. It makes sense that I may have maximized air out with gutting the mufflers and removing the silencers, but I think there still has to be some backpressure going through the catalytic converter. You did help me understand gutting it may not make a difference though. Actually, I’m concerned that I may have to baffle the system after the gutting, due to not having enough backpressure anyway.

Regarding a 2 in 1 exhaust system, verses the gas escaping from the belly as it might, I've found placing my hand over the end the stock (gutted) tail pipes, the pressure from each pipe feels amazingly the same. So I'm not convinced the feature of a 2 in 1 system provides the additional benefit for the cost.

As you've said, additional power can be obtained now by increasing the in-flow of air, yet I don’t want to add an air kit for additional performance for three reasons.

First, the cost again.

Second, I’m looking to make the long run with this bike, so I don’t want to wear it out quicker by being quicker (I've got Skullatore for that).

Third, I’m satisfied with the power. I’ve added the 1K-OHM resister in line to the “fuel heat sensor”, and it gave me a little more bite, And I run"taller" through the gears.

I guess the only remaining question is whether I’ll have to add baffles of some sort, which if I did, I would buy Big City Thunder, providing they have a fit, and only I will be able to answer that at the end of the day, but the other would be what change in sound might be expected, if any. If there isn’t a better sound I see no reason to do it at this point, and that’s what I’d like to know before doing this.

Oh, and I’m sure I’ll need a marble, cuz I’ve got some (unobtrusive) PoP with the present mods now, and a gut job can only make that worse.

Yours was a very good dissertation of the exhaust system! I appreciate you taking the time to explain it for all of us so concisely…

Thank you,

[tomk]

IMHO you're getting exaclty what you want with the gutting and you can't beat the price.

I too had the popping during decel and put the coasters in place of the reed valves. I understand that marbeling accomplishes the same thing. It worked.

Good luck with that!

[dogdoc]

marbling dont fix it 100%, i tried it and it helps alot but still pops on decleration on my '05 plus mpg went down a bit so i pulled out the marble and mpg went back to 42.

[nomadtom]

I've wondered, isn't there some type of exhaust piping that you could use to remove the goat prostrate,er, I mean belly? I've see hot rods with exhaust systems that look kinda like conduit you use to protect wiring...................the kind you can bend around corners. I don't know how durable it would be, but seems like it would work as long as the header pipe and whatever you rigged up in front of the mufflers were the same inside/outside diameter.
NomadTom
'01 Nomad
Portland OR

[tomk]

There was a guy somewhere who made a bypass pipe to replace the goatsbelly, you could switch it back if you had to quite easily. You may be able to find more info on Gadgets site as I cant remember for certain where I saw it originally.

NT -- look on Gadgets page. I think they called it a Dutch bypass.

[rlfaubion]

I've wondered, isn't there some type of exhaust piping that you could use to remove the goat prostrate,er, I mean belly? I've see hot rods with exhaust systems that look kinda like conduit you use to protect wiring...................the kind you can bend around corners. I don't know how durable it would be, but seems like it would work as long as the header pipe and whatever you rigged up in front of the mufflers were the same inside/outside diameter.
NomadTom
'01 Nomad
Portland OR

I wondered about that too. I believe I've heard of the idea but haven't heard of anyone actually doing it. I doubt it would look very good anyway. I'm hoping someone shows up here that has drilled through the honeycombs.

[richardd]

I have cut the goat belly
inside there is a honey cone for the converter
it is on an angle you need to study prior to cutting there is a visable line
where it is welded inside
a cut off wheel will make strait line for easy welding
back together. you will remove 1/2 of one side only.

[dogdoc]

i threw the damn goats bladder away and added V&H pipes and have been extremely happy ever since. besides the stock pipes are fakes.