Removal of the Cat

mark71

mark71

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OK Ive been thinking of cutting open the exhaust and removing the cat and then welding it back up again.

In theory it should flow a lot better but my question to all is has anyone done this mod before or know of any reason why I shouldnt attempt it.

Please answers on the back of a post card as usual and of course copious amounts of beer will be consumed before cutting commences always a good idea.
 
This cat-gut thread is already well drawn out.

To an extremely high standard....here.


CatGuts-6.jpg
 
Sorry shouls of been more specific, I am thinking of removing the cat on the 1200.

Many thanks

Mark
 
The question must surely be why bother cutting and hacking about?

Just buy the Remus headers and save the std untouched one to put back on when you sell the bike.
 
Got to agree with BTBR and don`t trash the original headers......

Take the new header option and kkep the original on the shelf,:thumb
 
One of the guys of the Malaysian GS Group, actuall a bike shop owner, has cut the cat, welded it all back together and said the power increase is very good. Not sure if the CAN Bus has to be altered though. If it does probably the local BM dealer will not look king on you play with his cat.
 
Why do you want to pump more pollutants into the atmosphere? Any performance gain will be small. If you really want to go faster get a different bike or do an advanced rider course
 
Catectomy

Bones said:
Why do you want to pump more pollutants into the atmosphere? Any performance gain will be small. If you really want to go faster get a different bike or do an advanced rider course
Click to expand...


I seem to remember cats cause more pollution until they are up to full operating temperature, which equates to about 5 to 10mls, about the length of the school run, lots of these done on a daily basis. These short journeys may not be common with a GS therefore don't apply, but can't see a comparitively few gutted cats are going to destroy the polar ice cap, just maybe parents, the school run will.
 
Bones said:
Any performance gain will be small. If you really want to go faster get a different bike or do an advanced rider course
Click to expand...

Are you talking from experiance or just in your opinion?

Fact, there is a huge differance in performance when the cat is removed.

Plus, it is not really a case of making it faster, more a case of uncorking that extra torque that lets you enjoy the bike even more.
 
And think of all the fuel you'll save not having to cart the mullacking great lump around, should off-set the emmisions :D
 
Probably being dim here, but won't the bike then fail the emissions test when it comes up for MOT? :hide
 
BTBR said:
Are you talking from experiance or just in your opinion?

Fact, there is a huge differance in performance when the cat is removed.

Plus, it is not really a case of making it faster, more a case of uncorking that extra torque that lets you enjoy the bike even more.
Click to expand...

It's just my opinion. I've seen dyno graphs comparing std and 'performance' pipes and no way would you describe the difference as huge. Anyway the thread is about removing the cat from a standard pipe so I suspect the gains would be even smaller.

Fact, most riders (esp. I suspect your average GS rider) can't use the performance available to them with a standard pipe.

For the record, I have an Aprilia RSV'R' with a race pipe because it sounds better, weighs a fraction of the standard pipe and the standard pipe looks like a dustbin (and didn't have a cat anyway). I wouldn't replace the standard pipe on my GS because I commute on it through built up areas (100 miles a day) and if I can clean up the emisions then I feel a little better about burning so much fossil fuel. Also the standard pipe looks OK and GS's sound like tractors with a loud pipe
 
Probably being dim here, but won't the bike then fail the emissions test when it comes up for MOT?
Click to expand...

I think this dpends on the age of the bike. As far as I know the cat only became a requirement recently so if the bike predates that requirement it should be OK to remove it.

Can't see why anyone would bother though. My GS is driven quite hard and, even fully loaded, have never wished I had more power. The cost and effort for a few extra BHP hardly seems worth it.
 
andyclift said:
Can't see why anyone would bother though. My GS is driven quite hard and, even fully loaded, have never wished I had more power. The cost and effort for a few extra BHP hardly seems worth it.
Click to expand...

You have cleary not tried it without then?

The cost - about £130 for a 1150, £200 for a 1200.

The effort - about one hour of your time to fit it.

The reward - huge, and its not all about extra BHP. It totally transforms the way that the bike responds, the midrange hook up instant. Much better for two riding.

IMHO it is the best single modification (other than adding extra lights of course:augie ) that you can do to a GS.
 
Advanced riding you say!!!!!!

Many thanks for all your comments on this subject however as anyone who has studdied engineering will know that the Cat does suck some of the power and drivability of the vehicle making no real difference in the fueling of the bike as that is all worked out by the size of the headers which when I fitted a full Akrapovic system on there it came up lean and burnt out one of the plugs.

And to the comments about getting some advanced tuition, well thank you but as a police advanced class 1 car and bike I think I might be ok but if you know a couple of tricks that maybe I have missed the please let me know.

Guys guess what I am trying to say is if you dont have something constructive to say then please dont say anything at all but thank you for your time anyway.

As I have a tig welder sat in the cornerof the garage I will be chopping out the cat soon and willlet you know what it is like, all those who have a full system on their bike will know the difference in power that can be obtained and most of the loss is in the cat just like the 1150.

Thank you for taking the time to read this and if you have something constructive to say the please do.
 
mark71 said:
And to the comments about getting some advanced tuition, well thank you but as a police advanced class 1 car and bike I think I might be ok but if you know a couple of tricks that maybe I have missed the please let me know.
Click to expand...

LOL!!
Made me larf :D
I agree about leaving the cat alone & buying a pair of headers. The Remus ones seem to go for about £200ish 2nd hand & you`ll probably get that back when you come to sell them on. :thumb2
 
Follow up

mark71 said:
Many thanks for all your comments on this subject however as anyone who has studdied engineering will know that the Cat does suck some of the power and drivability of the vehicle making no real difference in the fueling of the bike as that is all worked out by the size of the headers which when I fitted a full Akrapovic system on there it came up lean and burnt out one of the plugs.

And to the comments about getting some advanced tuition, well thank you but as a police advanced class 1 car and bike I think I might be ok but if you know a couple of tricks that maybe I have missed the please let me know.

Guys guess what I am trying to say is if you dont have something constructive to say then please dont say anything at all but thank you for your time anyway.

As I have a tig welder sat in the cornerof the garage I will be chopping out the cat soon and willlet you know what it is like, all those who have a full system on their bike will know the difference in power that can be obtained and most of the loss is in the cat just like the 1150.

Thank you for taking the time to read this and if you have something constructive to say the please do.
Click to expand...


Hope to see your thoughts & results post catectomy, especially mid range etc. as I do a fair bit of two up.
 
Why Bother

Ok to all you nay sayers I have taken the cat out and tig welded it back up costing about oh let me think not including my labour about £1 including having the lights on in my workshop (posh word for garage) and wow what a difference it makes as became so apparant once I had cut open the pipes.

As the headers ar chrome I painted them in zinc paint and as it is all hidden up by the clamp anyway there isnt that much to see at all.

So to everyone who said dont bother I say why waste all the BMW r & d work that they carried out getting the headers just the right size and dimensions and just liberate it a bit oh and of course save a fortune.

And if I could work out how to post some pics I would not that I am thick or anything, guess I better pay my subscription again.
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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