F800GS - catalytic smotherer

Aprart from wanting to remap the throttle to be smoother, I also want to ruk out the catalytic converter. My imagination is telling me there is a spot where it feels as if something is holding the bike back while accelerating and I am so sure it will feel better without a frog in the throat. I've heard of the 1200 okes doing it, most of them happier - any 800s who've done it?

I am not aware of someone who's done it to an F800, but I found this interesting read:

http://www.motorcycle-exhausts.co.uk wrote:Decat Exhausts

A range of Stainless steel lightweight Decat Exhaust pipes for many popular models. Let's your engine breath and sound like it was designed to.

There seems to be a lot of confusion surrounding what a 'Cat' does, what happens when you remove it and the MOT requirements. Here are the answers:

• The catalytic converter (CAT) helps to convert carbon monoxide into carbon dioxide. It converts the hydrocarbons into carbon dioxide and water. It also converts harmful nitrogen oxides back into nitrogen and oxygen.
  
• The lambda or O2 sensor, is the key sensor in the engine fuel control feedback loop. The ECU uses the O2 sensor's input to control the amount of O2 in the exhaust gases and balance the fuel mixture, keeping it within a very narrow Air/Fuel ratio band of +/- 0.03% of 1.0 λ
  
• The O2 sensor is fitted in the exhaust before the CAT, so removing the CAT will have no effect on the function of the O2 sensor, fuel mixture or the running of the engine other than to let it breathe better.
  
• The current MOT test does not include a gas analyser check and as far as we are aware it will not be introduced in the near future, so you are quite within the law to remove the CAT in the UK.

So it does not seem to do anything other than making it sound better, and caring a bit less for the environment. And a bonus is that you can use leaded petrol in case of emergency. Also read this interesting article on the evils of catalytic converters (except for the fact that it weighs a lot).

I have considered doing it to the 1200GS, but I read up on it and it seems to involve blow torch cutting and welding. Not sure whether the 800GS will require the same "treatment"???

Interesting! I’ve also been pondering about removing the CAT from my Dakar as I think it puts unnecessary stress on the engine. I can certainly understand why a 3l V6 4X4 needs to have a CAT (considering the environment), but not a 650cc? Anyway, I believe it also entails the same procedure as the 1200, which I don’t really want to do. Furthermore the feedback I got from more informed people (regarding performance and engine stress) is that it wouldn’t really make a deference…?

Marnus wrote:
So it does not seem to do anything other than making it sound better, and caring a bit less for the environment. And a bonus is that you can use leaded petrol in case of emergency. Also read this interesting article on the evils of catalytic converters (except for the fact that it weighs a lot).

I have considered doing it to the 1200GS, but I read up on it and it seems to involve blow torch cutting and welding. Not sure whether the 800GS will require the same "treatment"???

Tx, interesting read. Haven't thought about the weight a lot, but sure that might make a difference. One of the (few!) negatives of the 800 is that I still do not have the confidence off-road that I have with the Dakar, and I think a big part is the weight difference - in my head the 800 feels closer to a 1200 weight-wise than a Dakar, so a few kg's less might just push it to the right side of the boundary.

I am also big on saving the environment, and yes, every bit helps, but I read somewhere that all the bikes in Europe(?) together in one year do not emit as much bad stuff as one cross Atlantic trip by a Boeing. So...

When I bought the bike my friendly salesman told me they can do the removal for about R400 or so, cause yes, it does involve cutting and welding. If I remember correctly he said it adds about 3kW of power or so and the guarantee won't be affected if they do it (don't quote him/them or I on this!!)

dakardrix wrote:One of the (few!) negatives of the 800 is that I still do not have the confidence off-road that I have with the Dakar, and I think a big part is the weight difference - in my head the 800 feels closer to a 1200 weight-wise than a Dakar, so a few kg's less might just push it to the right side of the boundary.

I found the exact opposite when I had the 800. It behaved a lot better than my 650, and it was WAY easier to ride, even on the harder techical stuff I did on it on the Saturday. It is heavier than the 650, but much easier to handle.

My 2c

I ride an 1150GS, and also decided to ditch the Converter after not being able to refuel with unleaded at Kranskop in KZN. Bought and fitted a BMW 'Y'- piece and a Stealth end can. The 'Y'-piece makes provision for the Lambda sensor, so no harm no foul. There is about a 2kw increase between 3500 - 4500 rpm, but the kicker is that at 130-140kph, I can travel roughly 30kms further on a tank of cream soda. Not to mention the 7kg weight saving!

Sharkie wrote:

dakardrix wrote:One of the (few!) negatives of the 800 is that I still do not have the confidence off-road that I have with the Dakar, and I think a big part is the weight difference - in my head the 800 feels closer to a 1200 weight-wise than a Dakar, so a few kg's less might just push it to the right side of the boundary.

I found the exact opposite when I had the 800. It behaved a lot better than my 650, and it was WAY easier to ride, even on the harder techical stuff I did on it on the Saturday. It is heavier than the 650, but much easier to handle.

My 2c

I agree in terms of balance - the bike is easier on open gravel and smoothish single track/jeep track. Tight doen't matter. It's the rocky stuff where you can't 'open up' and have to climb rocks slowly (where the stiff clutch and jerky throttle really challenge me) and those places where I come to a sudden standstill with my foot in the air and only one leg to support, and pulling away from there, and so on - that's where I miss the Dakar.

But I love the bike!!!!!! Those are just challenges that I have to overcome.

That's why I think the remapping is needed to remove the jerkiness. The CAT removal is just for general health (the bike, not the world). Now how to change that clutch to be easier??

So the cat's gone and the mouse is boss - triple click!!

Sound is only a little bit deeper, nothing to write home about. Performance - well, very subjective but I think I feel the difference most between 5,000-8,000 revs. I remapped at the same time, so overall it feels smoother and different.

Done by Bavarian, was Lenny's first 800GS to do! So hopefully the R&D is done for the rest. Welding job doesn't look the greatest, but as long as it holds up I'm happy. Like my bike to look rough and tough (one of the things I don't like about BMW DS bikes, they look too nancy pancy for me )

Cost was more than I anticipated. Was told last year it would cost R400, was charged nearly R800.

Overall I think I'm happy, will watch the fuel consumption with interest.

Many happy catless km's!!!

You should have done the de-cat and the remapping at different times to get the full effect of both... me thinks

You're right - just can't stand the schlep of taking the bike in again and again, been there enough over the last two years!

So do you now fill up with LRP?

No, but I can if I must. Anyone can use leaded, your cat is just deemed useless the moment you do it. Apparantly...

Marnus wrote:.........(except for the fact that it weighs a lot)............

This is a myth.

In the recent past I have handled two cats myself – the F800ST and the K1300S

The weight of the F800ST’s cat is insignificantly low…….I would say no more than 200/300 gram. I have weighed the can of the K1300S which includes the cat. Although the 1300’s cat is double the size of the 800, the combined weight of the can, cat and cloth is only 3.7kg. Would say the cat is no more than 300/400 gram