Remove catalytic conterter(s)?

[Maki]

Hi, I have noticed that some new bikes come with catalytic converters. Is there any reason not to remove those and replace them with straight pipes, to save weight and reduce back pressure? Are there any rules about emissions here in NZ? Will there be any issues with WOF if I take the cat out of a new bike? Thanks, and apologies if this has already been covered. I did a search...

[Grub]

Yep theree's a reason now not to remove them. Govt announced this month that WoF will require that converters fitted to bikes will still be there at WoF time.

Not sure when that comes into effect or how retrospective it is ... but sounds like it's happening. I guess thinking Green, it kind of makes sense.

[Madness]

There's this thread.....

Just stick to old bikes. Carbies are great!

[babyblade250rr]

I don't know how much of this is true because it's something ive only been told and i'm not sure if it's related to all modern motorcycles but with the yamaha Exup system apparently the cat converter plays a big part in relation to back pressure for the exaust valve which optimises torque under load so i've been told removing it will decrease performance rather than gain!!

perhaps someone that knows can enlighten??

[The Stranger:Me]

Hi, I have noticed that some new bikes come with catalytic converters. Is there any reason not to remove those and replace them with straight pipes, to save weight and reduce back pressure? Are there any rules about emissions here in NZ? Will there be any issues with WOF if I take the cat out of a new bike? Thanks, and apologies if this has already been covered. I did a search...

They have a rule in the system which would make it illegal to modify an emission system, but it's not here yet.
Sweet FA weight in a cat and they flow ok. I just removed the cat from the collector on my Fazer. There was a flat spot between 5,000 rpm and 7,000 rpm due to the design of the headers, removing the cat has helped in that area.

[HDTboy]

At first I was sceptical about gutting the cat on a modern bike, then I tried it on Two Smoker's first ZX6 race bike, and the arse dyno came back with more power.
A week later I fitted a full Leo Vince titanium exhaust which made my original mod academic anyway.

[Maki]

Thanks. I guess it's no big deal either way then.

[The Stranger:Me]

I don't know how much of this is true because it's something ive only been told and i'm not sure if it's related to all modern motorcycles but with the yamaha Exup system apparently the cat converter plays a big part in relation to back pressure for the exaust valve which optimises torque under load so i've been told removing it will decrease performance rather than gain!!

perhaps someone that knows can enlighten??

After my experience with my GSXR 1000, one of the first things to go on my Yamaha was the Exup. Next thing to go was the cat. It didn't cure the poor header design, but it did go some ways toward helping.

On the GSXR they have the same exup type system, but they refer to it as a sound attenuation device - go figure.

[Monsterbishi]

There isin't an engine out there that won't benefit in the performance department by removing its cat, the surface area/friction of the honeycomb is simply massive.

Removing them from bikes imo is easy enough to get past most wof guys, they're not going to carry a list of what bikes should, or shouldn't have them, most have a hard time understanding floating calipers, let alone what should be attached to the arse end of a motor!