De-cat chat

De-cat chat

I own a ZZ1400 and I want to know if it is illegal to remove the catalytic converter? I see loads of people on various forums who have done a ‘de-cat’ and they reckon it makes the bike quicker.

However, just because loads of people do it doesn’t make it legal. I don’t want to go to the time and cost of taking off the exhaust pipes and taking out the cat only to find I have to but a new exhaust system later.


Firstly, good choice of bike (I too have a ZZR1400!) I have been asked this question a lot lately and you are absolutely correct. Just because someone on a forum has done it does not make it legal. In recent years, there has been a real push to make cars and motorbikes alike cleaner for the environment and to be fair none of us want to be breathing in smog.

The law has evolved over the years and long story short, it states it is an offence to use on the a road a vehicle which has been modified in such a way that it no longer complies with the air pollutant emissions standards it was designed to meet (if you are ever struggling to sleep I recommended reading the Road Vehicles (Construction and Use) Regulations and the Road Traffic Act 1988. It is WAY more effective than counting sheep).

If you get caught doing this i.e. ‘de-catting’ a motorbike that should have a catalytic converter etc. you could be looking at a hefty fine. Bizarrely though, as matters currently stand, motorbikes do not have their emissions tested as part of the MOT and there are load of companies out there ‘de-catting’ bikes.

Andrew Prendergast

Motorcycle Monthly October 2018

Posted by Andrew Prendergast. Last modified: December 21, 2018 at 12:00 pm

Andrew has been riding motorcycles since he was 10 years old and currently rides a ZZR1400 as his daily commuter whether it is sunny or snowing. In addition, he is currently restoring an old Honda CB750 K1. Andrew practices across all areas of motorcycle law, with his practice involving both civil claims and motoring defence work.
Disclaimer: The legal advice and statements contained within this/these articles is correct at the time of printing. If you are seeking legal advice after a motorbike accident please contact us to speak directly with one of our lawyers.


  1. Nick DoranJune 28, 2019

    How does this work with bikes where the standard exhaust is no longer available?

    I’ve just bought a VFR 800 that would have been fitted with a cat from the factory. Presumably this was to meet emissions regs at the time. These were known to rot and mine has been replaced with a full SS system. The standard exhaust is no longer available so I couldn’t replace it if I wanted to. Am I breaking the law?

  2. Lyn DarkesJune 28, 2019

    Try an MT10 with a Leo Vince baffled De-Cat……’s addictive! Should be on the NHS for lifting your spirits!

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The MCM legal column is compiled by managing partner Andrew 'Chef' Prendergast and his bike-riding barristers and solicitors at White Dalton Motorcycle Solicitors.

The firm deals with personal injury claims and its sister company, Motor Defence Solicitors, deals with all the motoring offences.

White Dalton lawyers have a vast knowledge of bike law, and they have full bike licences, too. They don’t act for insurance companies or the prosecution.

White Dalton is Britain’s premier specialist motorcycle law practice, and if its professionals don’t know the answer to your question, there probably isn’t one. Don’t rely on the advice from your insurance appointed solicitor, get proper independent advice.

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