BMW R1200R R1150R/T F800 K1200R R1100R/T R1250R RnineT Message Board

Can anyone please advise how I remove forever my catalytic converter. I think a Y piece is involved and maybe some adjustment to the fuel system but cant find any definitive on the subject. So far my cat has caused me untold trouble here in Manila where high outside temps and heavy traffic abound.

What parts do I need, where do I get them, installation pitfalls, can I reuse my existing stock muffler etc etc.

Cant afford any more major breakdowns. Remember I live in the Philippines before reminding me about pollution or legal considerations.

Thanks in advance

A quick google returned these hits. I think $300 US is a bit steep for something I could probably weld together in a few hours but...

http://www.sjbmw.com/parts.asp?searchty ... t%20System

and

http://www.starcycle.com/street/remus_bmw_06.html

Look for the section on the page below -

99-05 R1150R/GS/ADVEN.
cat elimin. Y pipe - use w/stock or Remus canister 0107-087799
$334.95

BTW - Fixed those side cases

snowprick

The easiest thing to do is to remove the cat and cut a window in it so as to gut it out, once gutted, have a shop weld the window back and you are set to go.

Re-install the cat, the bike will look original, the muffler will remain, the exhaust will have a mellow sound, the bike will run better and have a crispier acceleration and the A/F ratio will not rquire any adjustment as it is within the ECU capabilities to adjust to the new free flowing exhaust.

See....a win-win situation at least for the Phillipines.

Boxermania,

That is a neat solution! That never occurred to me as I have wanted to do the same but did not want to pay the price for a y-pipe. But I could easily cut into the cat and gut it. Have access to a good welder and equipment too. What is the interior construction of the cat? One single cavity or are there baffles inside to deal with?

My issue with the cat is the tremendous heat that comes off of it.

wayne

boxermania wrote:snowprick

The easiest thing to do is to remove the cat and cut a window in it so as to gut it out, once gutted, have a shop weld the window back and you are set to go.

Re-install the cat, the bike will look original, the muffler will remain, the exhaust will have a mellow sound, the bike will run better and have a crispier acceleration and the A/F ratio will not rquire any adjustment as it is within the ECU capabilities to adjust to the new free flowing exhaust.

See....a win-win situation at least for the Phillipines.

boxermania,

YOU ARE DE MAN! When its done I will post a response. Assuming I can find a TIG welder in the Philippines.

Hi Snowprick,
I reckon opening the cat is a nice option because the exhaust still looks stock and it doesn't attract unwanted attention. Although you probably won't have any trouble finding a TIG the job can be done using a stick welder using stainless steel rods. I did it this way and you can't tell the cat has been modified.

Using an angle grinder with an ultra thin cutting disc you can slice the cat along its seams - going over the top of the inlet and outlet pipes. The only problem with just gutting the cat is that you end up with an open box and the gas has to find its own turbulent way out.

However, the inlet pipes form a nice two into one inside the cat after you remove the converter bit so you can join that to the outlet with curved tube (stainless is best), drill a million holes in the pipe and pack the box with fibreglass or rock or stainless wool before rewelding. You end up with a nice stock looking resonator. The down side is that if you have to pay someone to do the work it would probably be cheaper to buy a two into one from someone like Staintune in Australia. Anyway, have fun fiddling.

desmophil

Your point is well taken, from my perspective the majority of the restriction in the system comes in from the cat, with the muffler providing he rest albeit not much as proven by those that have removed the muffler in lieu of a short tailpipe.

In the scheme of things the cat volume is relatively small and the gasses will find the path of least resistance.......as a matter of fact as the gasses expand n the empty cat I would thin that it would amplify the return sound wave and will further improve the scavenging of the cylinder, however, consider this a a figment of my imagination as I have no proof whatsoever.....

BTW.....how is the sound of the muffler after the cat mod?

I removed my cat on my '04RT about 3 years ago because I didn't like all that heat in close proximity to the transmission and it didn't seem to me that there was all that much air flow between the cat and the trans to provide cooling especially in slow traffic. I took the cat/muffler assembly to a machine shop and told them where to cut and they did the deed and you can't tell it from stock. Only charged me about $40. I did not realize any performance improvement and didn't expect to as the cat is non-restrictive so any improvement was all in my mind probably enhanced by a throatier exhaust note which is pleasing to my ear but performance gain? Sorry, no cigar.

I removed the CAT from my 2000 RT-P and noticed the following:

http://www.myr1100rtp.netfirms.com/catelement.htm

Just out of interest, my New Zealand-market 1997 R850R does not come with a CAT anyway.

I'd take the whole thing into a local shop and get them to do the business... wouldn't think it will cost much over there.

Do remember to reset the motronic unit (detailed in the above link)

cheers
Tracy

Thanks gang for the support. And special thanks to Tracy for the great tutorial, now I know what to expect. Yes labour is not expensive here but the challenge is to find ability. Once I get my bike back from the clutch mender, then the Cat is going to get the chop.

TracyPrier

Nice tutorial and well detailed. Definitely something fairly easy and inexpensive to do.

One of the facts of life that most owners don't realize is that the compounds inside the cat (for catalyst that will precipitate the reaction) will eventually be consumed (fully reacted) rendering the item useless, another end result is loss of flow (like in plugging up). The first one will not affect the engine operation, just the emissions; the second will affect the engine operation. The early signs of cat plugging would be increased engine temperatures....unfortunately not having a temperature gauge makes troubleshooting difficult, the other is to tap for a pressure gauge (will have to have a snubber and be liquid filled to eliminate the pressure pulses) ahead of the cat and see how the pressure changes over time.

In my line of business a 10% reduction of efficiency is cause for concern, a 20% requires action. I would like to see how a cat looks off a bike with 100K miles. In the auto industry and by law they should be efficient and guaranteed by the OEM for 50 K miles, don't know if this is applicable to motorbikes.

thanks guys

As an ex-car mechanic (from about 20 years ago admittedly) my view on CAT's might not be scientific but I have come to the following conclusion:

Every vehicle I have removed the CAT from (either Euro bike or Japanese import car) has benefited by getting better mileage-per-tank and running better.

Based on this I reckon you are better off without one and using LESS fuel to get from A to B than reducing the performance of the engine and making it work harder to do the same thing... and thus burning more fuel.

I really noticed this with the RT-P. I could go up a hill and find the engine not labouring so hard in any given gear... I didn't have to change down as early.

The bike just felt like it was running easier and it certainly started and idled better and the notorious "surge" pretty much went away.

Also, I figure I am causing less polution just by BEING on a bike rather than in a car. My wife and I own one Nissan Bluebird and whatever bike I happen to have and that's it so I reckon we aren't stomping around with that big a carbon footprint.

Plus... with all this fretting about CAT's etc... all that "good" must pretty-much be deleted by one days polution output in an industrial town in China... or India... or the former sov countries.

Well that's just my view on things anyways

cheers
Tracy

I respectfully repeat, the catalytic converter used on these bikes is not restrictive if it is in good working condition. Therefore, removal of a properly functioning unit will not increase performance or save one ounce of fuel. If a machine is running rich or if one fills up with leaded gasoline then the converter could over heat and become partly plugged. Removal or replacement of a plugged cat would then obviously result in improved performance. I wager not many of these bikes have a plugged cat. Hence any perceived performance improvement is largely a result of what goes on between one's ears. I like the sound of my RT without the cat and 40 bucks didn't break the bank so I'm happy.

Sorry mate but my actual, real-world experience begs to differ.

My bike was an ex-CHP bike which came over straight from the BMW dealer. It would always have been run on unleaded in CA I'll wager and it certainly ran on unleaded here.

I took careful note of fuel consumption over several weeks before doing the deed and noticed a MARKED improvement of an extra 25 miles per tank... same type of running, same fuel etc. Only difference was no CAT.

I have observed the same kind of improvements when this has been done to cars as well.

And no, it wasn't blocked either as I could easily see right through it.

Theories are wonderful but I think I'll stick to real-world experience.

Cheers
Tracy

This is an interesting topic and I agree with just about all comments.

With the cat turned into a resonator plus stock muffler I could not honestly say that the bike definitely, absolutely, performs better. With a Staintune muffler the note is pleasant but still not loud even with the removeable restrictor removed, and I think maybe it goes a bit harder. But that could be down to the substantial reduction in weight of the system although the cat body is still heavy.

Boxermania is spot on with his thoughts about the returning sound/pressure waves helping scavenging. Depending on what you want to achieve, a good competition exhaust should have a collector box at the joining of the primary pipes that is x times the volume of one cylinder. There is a formula that I can't remember to work it out but, from memory, it includes valve or port sizes and rpm at max power or something. However, it is unlikely that you could fluke it with the removal of the guts of the cat and it works only at certain rpm, not through the range.

Although the stock muffler is quite restrictive, I disagree about the idea that the gases find the flow path of least resistance etc. One of the reasons you go to so much trouble when designing a good system is because any turbulence or vortexes effectively reduce the diameter of the pipe and therefore restrict flow (depending on how appropriate the diameter was in the first place).

Incidentally, after going to all that trouble I put my original stock cat back on. I am an environmentalist and figure that if I am not prepared to personally try to make a difference then I have no right to ask the folks in India and China to clean up their act - and then we would all be riding bicycles in a very short time.

But it is still fun experimenting don't you think!

Well Tracy, could it be you have these positive results after cat removal because you are in the southern hemisphere where water whirls counter clockwise as it goes down the drain? Or maybe it is the influence of the Southern Cross as it works its spell on man and machine.

Hey, only kidding. All I can say is I found no difference except nice sound. Maybe your muffler/cat assembly is different from mine on an 1150RT? Maybe if yours is physically different you could be getting a scavenging affect which could maybe produce the differences you see?

Hey guys, this is all very interesting stuff but when all said and done the objective here is to reduce heat and the removal of the guts I am sure will do the trick. Thanks for all the input. We really have a mine of good information on this forum.

And everyone is entitled to their theory or practical experience, the object is to share such and hopefully assist the poster in need.

That being said, kudos to all that shared their views.......

That seems odd that you wouldn't notice any difference other than sound... not doubting your findings here, just intrigued.

And I can't attempt to duplicate my results either 'cause the 850 don't have no CAT... which of course saves me a job which suits me

The first time I did this was on my old 1996 Toyota Celica and by replacing the CAT with a glasspak, straight-thru muffler I increased mileage by a good 55km a tank which is why, when I found out the RT had one I thought, "right, THAT's coming out pronto"

By the way, down here we don't have any legal requirement for CATs so I'm not breaking any laws for anyone who is interested.

cheers
Tracy

Jammess wrote:Well Tracy, could it be you have these positive results after cat removal because you are in the southern hemisphere where water whirls counter clockwise as it goes down the drain? Or maybe it is the influence of the Southern Cross as it works its spell on man and machine.

Hey, only kidding. All I can say is I found no difference except nice sound. Maybe your muffler/cat assembly is different from mine on an 1150RT? Maybe if yours is physically different you could be getting a scavenging affect which could maybe produce the differences you see?