Catalytic Converter - Catectomy Question

[Beaze]

I'm thinking about doing a catectomy on my '05 Rock and wanted to get some insight prior to permanently changing the bike. Thanks Beemeridian for the info on your cat mod BTW!

1. What's the best way to remove the cat element once inside the box?
2. What size welder did any of you use and which setting did you put the welder on? From the pictures (and it's hard to tell) the metal is only about 1/8 thick?
3. What performance increases/decreases did you notice after the modification?

Question 3 is should really be read as #1 as I'm mainly concerned with adversely affecting the felt performance of the bike. I hear you don't need to fiddle with the motronic after doing this, true? I recently removed the muffler and ran an exhaust tip and found that the bike seemed to have a bit less low-end torque. Has anyone found a similar reaction to gutting the Cat?

[Remow2112]

I have just gutted a cat on my 2004 r1150r. First cut the back panel open, DO NOT cut a panel in the top. You don't need it.

The cat element is some foil/metal type structure that is radically different then the ceramic I am used to on cars. Took forever to get it out. Here is the trick. Get a flat blade screwdriver and hammer it down the sides of the element where it contacts the sides of the pipe. Do this all the way around. Then grab the element with pliers and pull/twist till it comes out. If it does not twist or pull out go around the edge again.

No idea about the welding. I have a friend that is going to do it for me. (Since I have not learned to weld yet.)

I am currently running with the cat and no muffler just a short down turn pipe. Sounds much better and I can now fit a full size system case on the left side.

I am considering running a gutted cat and a short pipe. Free flow exhaust. My only concern is that the pipes are a short running and might burn the valves. Anyone here tried free flow exhaust?

HTH,
Dan...

[Airman]

Dan,

I think you're going to find the gutted CAT only, to be pretty loud. I have run the usual combinations, Y-pipe and muffler, CAT only, and have not been satisfied with the sound. I think I will probably go to the Y-pipe and Supertrapp muffler. You might try the stock silencer with the gutted CAT, but with a Y-pipe and stock silencer there is little difference in the sound, in fact I think the CAT only sounds better. I'll be interested to hear your results.

[cricman]

I did mine a few years ago. The housing is roughly 16 gauge stainless. It doesn't require a lot of welding power to stitch it back together. I used a tig welder and 308L filler. If you can find a 4 lb spool of .30 308 mig wire and straight argon, you can mig weld it back together. To remove the corrugated catalyst, I used a 3/4" spade bit and a heavy duty 1/2" drill to gut the catalyst. The gutted cat and stock muffler is still very quiet. The only reason I gutted my installed cat (I have a stocker, in case "THE MAN" starts asking questions) was to reduce temps under the transmission.

Good luck,

cricman

[snowprick]

I did mine a few years ago. The housing is roughly 16 gauge stainless. It doesn't require a lot of welding power to stitch it back together. I used a tig welder and 308L filler. If you can find a 4 lb spool of .30 308 mig wire and straight argon, you can mig weld it back together. To remove the corrugated catalyst, I used a 3/4" spade bit and a heavy duty 1/2" drill to gut the catalyst. The gutted cat and stock muffler is still very quiet. The only reason I gutted my installed cat (I have a stocker, in case "THE MAN" starts asking questions) was to reduce temps under the transmission.

Good luck,

cricman

cricman,

Where did you make the "cut". Do you have a photo or drawing?

[Beemeridian]

11

[snowprick]

Hopefully this will be useful to you:

viewtopic.php?f=2&t=16780&start=20

Beemeridian

Thanks very much, that looks very "dooable" I just need to go by an angle grinder and a couple of one mm cut off disks.

[towerworker]

Cricman--

I too have considered gutting the cat for heat related issues. How was the performance affected? I'm not at all concerned about power increase (if any) but I'm told changes in back pressure may be an issue on overall performance.

Wayne

[Beaze]

I noticed a decrease in torque when running just the cat and a tip. I just gutted my cat today and welded everything back together. I have yet to ride it but it seems to be only slighty louder than with the element in the cat. I think this is a good sign as the OEM muffler should provide adequate back pressure. I'll post an update once I get it out on the road for a test.

That metal is seriously THIN! I had to weld a tack on either side of the gap and then bridge it. It kept melting back further away from the center of the gap. I welded it back together and then ground the weld down and re-welded over the first one. I only have one small leak now! I'll take everything back off when I'm feelin squirley and fix that but it shouldn't matter.

Oh yeah, got a brand new display model welder for $80 today

[snowprick]

I noticed a decrease in torque when running just the cat and a tip. I just gutted my cat today and welded everything back together. I have yet to ride it but it seems to be only slighty louder than with the element in the cat. I think this is a good sign as the OEM muffler should provide adequate back pressure. I'll post an update once I get it out on the road for a test.

That metal is seriously THIN! I had to weld a tack on either side of the gap and then bridge it. It kept melting back further away from the center of the gap. I welded it back together and then ground the weld down and re-welded over the first one. I only have one small leak now! I'll take everything back off when I'm feelin squirley and fix that but it shouldn't matter.

Oh yeah, got a brand new display model welder for $80 today

Beaze,

How thick was your cutting tool?

[Beaze]

How thick was your cutting tool?

I used a very thin cutting wheel on a 4.5 inch grinder. If I had to guess, I'd say it was no thicker than 1/8 in. It left a very minimal gap but the metal is so thin that my welder, even on the lowest settings, was burning straight through it. I was using a 90 amp, flux core, wire fed welder and had the wire feed set on 1.5 out of 8.

[cricman]

Cricman--

I too have considered gutting the cat for heat related issues. How was the performance affected? I'm not at all concerned about power increase (if any) but I'm told changes in back pressure may be an issue on overall performance.

Wayne

Honestly,

No discernable difference of any kind regarding performance. Okay, maybe it revved a tad quicker in neutral. Sound wise, only a bit of added "burble" at idle. I mean just a hint, to my "trained" ears.

As far as the cutoff tool; the superthin ones used on standard 4" or 4-1/2" cutoff wheels work great and are available at the blue or orange big box stores. I like the Norton brand, but the Dewalts also work.

And for welding power, that 90amp fluxer is great for "mower decks" (A common advertising claim of virtually all low end welding power supplies), but I'd choose something with a few more settings and a shielding gas option. Flux welding, setting for setting (Voltage and Wire Speed) runs hotter and is a bit corrosive, unless you completely remove all traces of flux (yes, even on stainless). Since there is no good way to remove the flux from the inside of the weld, it can slowly eat itself away where the mild filler and stainless parent metals join. This will be exacerbated by the heating-cooling-condensation cycle your exhaust system will produce. If I were to use Mig, I'd go .30" max wire at about 14-14.5 volts, and a slow to medium wire speed (a fps number doesn't pop into my head at the moment.) I guess I'm lucky in that I have a setup that will allow me to be that precise in my mig welding voltage. I would use straight argon (cooler than the dual or tri-mix gases) and would back-purge the CAT by filling it with argon (capping the three pipes and flowing in argon to remove the ambient atmosphere.)

And for the record, I am NOT a professional welder, but I did stay at a Holiday Inn Select. If there are any pros here, please correct as necessary.

Good luck,

cricman

[boxermania]

+1 cricman.....MIG it is for SS welding.....flux core wire will do the job........

I didn't stay at Holiday Inn Select, but attended the Pay Me Know Or Pay Me Later School.

[Beaze]

I base all of my welding of off the ACME instruction book so don't ask me . The flux core wire will do the job (I just did it) but it does melt the metal WAY to fast for my liking. Once I had the box sealed up I had to go back and grind the welds down and re-weld it to get a good seal. But for 80 bux and 2 hours on a Sunday afternoon I couldn't be happier

[Remow2112]

Got my cat welded up yesterday and my friend said that he had never seen ss melt like what our cat is made of. So, can you pull the cat using the side stand? Can't use the center since it is attached to the cat. For those of you that have pull the cat what is the preferred method?


Dan...

[Beaze]

Got my cat welded up yesterday and my friend said that he had never seen ss melt like what our cat is made of. So, can you pull the cat using the side stand? Can't use the center since it is attached to the cat. For those of you that have pull the cat what is the preferred method?


Dan...

I had the bike on the center stand while I removed the CAT. The only thing I had to pull was the left bar on my Wunderlich engine guard. Other than that it was as easy as pie! There are two T-8/10 (can't remember) torx screws that the center stand is bolted to the cat with. These are not for the center stand but act as retainers and supports for the cat. You'll need the bike on the center stand in order to pull the cat element off of the headers as it takes some elbow grease to get it to disconnect from the headers. Good luck!

[boxermania]

Beaze

No offense intended.....just agreeing with cricman on the preferred method, great that the flux wire worked for you........and adding a bit of levity to boot....

[Beaze]

Beaze

No offense intended.....just agreeing with cricman on the preferred method, great that the flux wire worked for you........and adding a bit of levity to boot....

No offense was taken Boxer . I was just letting everyone know that my Wiley Coyote method worked too. Hopefully I won't be the one with a big rotted hole in my cat in a year from the welds rusting out8-[ . I actually didn't know about the MIG/Argon gas thing or about Flux core wire causing rusty welds...ya lurn sumfin every day!

[Remow2112]

Ok, the great cat experiment is complete. I am now running a gutted cat and a short down turn pipe. It does not seem loud at all. At least not to me. I live in Tucson land of mostly Harley riders that take the mufflers off. They are loud.

The bike revs quicker and seems smoother on acceleration. It has more of a rumble to the sound and kind of grunty. During warm up up (enrichener on) When I reved it sitting on the center stand I saw some black smoke, same with the enrichener off and on stand. I will have my GF drive behind me tomorrow and look for black smoke. My guess is the o2 sensor and computer have not balanced out for the free flowing exhaust.

Word of warning. When my cat got welded some of the liquid metal formed small balls that fell into the inside of the cat. I thought I shook them out. I was wrong I can hear them rattling around on decel (sigh).

So far it has been worth the effort. During my quick test ride I did not get any backfiring.


Dan...

[riceburner]

One thing about riding the bike with a Y-piece or gutted CAT and any can - the HEAT that normaly builds up in the CAT is now going to build up in the can (especially if you use a restricting can, eg the OE can).

This can be enough to melt panniers - which has happened to me (Y-piece and OE can). The gases coming out of the can were hot enough to melt the pannier some 2 or 3 inches AFTER exiting the can.