Emissions impossible; what Euro 4 really means

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Will new legislation to reduce the amount our motorcycles pollute the planet also reduce our enjoyment? This is the MCN guide to Euro 4 laws and what it means for you

uel is naturally fun and exciting stuff. But at the other end of an engine, exhaust gas is hot, smelly and toxic; harmful enough to need regulation. And that’s where Euro 4 comes in.


What is Euro 4?

Euro 4 is the name of legislation that puts a limit on the emission of pollutants by new vehicles. It covers all mass-produced vehicles sold in Europe, and is legally enforceable.

As far as bikes are concerned, Euro 4 is contained within a broader European directive called Regulation (EU) No 168/2013, which lays out the requirements for new bike approval (not just number plate dimensions and how far apart the indicators should be, but the definition of types of bike, what the importers’ and manufacturers’ responsibilities are etc. It also contains a requirement for anti-lock brakes).

So if you want to build a bike in large numbers and sell it in Europe, the Regulation tells you what you can and can’t do. And the Euro 4 part of it tells you not just how clean its exhaust gasses have to be, but how much naturally evaporating fuel it’s allowed to emit, and begins to ensure it meets the regulations for the duration of its working life.

How it differs from Euro 3

Euro 4 is tougher to pass. Euro 3 was introduced on new models in 2005 (and existing new models in 2006), and it in turn placed tighter limits on the carbon monoxide, hydrocarbons and nitrogen oxides permissible in exhaust gas than Euro 2. Manufacturers were forced to fit bulky catalytic converters to change these toxic gasses to less toxic ones, and to use fuel injection to control precisely how much fuel enters the engine in the first place.

Bike engine development became a battle to be miserly with fuel, using it only at precisely the right moment, to burn it completely and efficiently, waste as little of the energy created as possible, and to treat the exhaust gasses effectively on the way out. All this at the same time as making more power than ever.

Thus, in the mid-2000s, some bikes got heavier, some got snatchy throttles, and some got both. Suzuki’s 2007 GSX-R1000, complete with a catalyst in its twin exhausts, weighed more than its K5 predecessor and felt it. Yamaha’s FZ1 Fazer (and many others) came with a throttle like a switch as fuel injection engineers developed the expertise to juggle tiny amounts of available fuel with the complex loading demands of a bike engine.

Euro 4 places even tighter limits than Euro 3, with a couple of extra anti-emissions measures added (see table overleaf). As well as fewer toxins in the exhaust gas when the engine is running, bikes will also have to pass an evaporative emissions test, run onboard self-diagnostic systems, and come with a requirement for manufacturers to prove the bike will still pass the tests after a specified mileage.

Vapour from fuel contains a much higher proportion of unburned hydrocarbons than exhaust gas, and as soon as you fill your tank they start venting to the atmosphere via a breather pipe. Euro 4 limits how much is allowed to escape.

The standard automotive solution is to vent fuel tanks into a canister instead; on bikes, it’s about the size of a 6v torch battery. Inside the canister is a carbon compound (often charcoal) that absorbs fuel vapour like a sponge. When the engine is running, the fumes are vented back into the fuel system (creating further headaches for fuelling engineers).

So, from 2016, Euro 4 bikes will have to pass a SHED test (Sealed Housing for Evaporative Determination) in which they’re literally stored in a container and have the fumes they give off measured.

Bikes will also have to have onboard diagnosis (OBD1) systems fitted, in which the bike measures and records the status of its emissions management systems, giving plug-in fault-finding and status updates for service technicians (who can then tell if a bike is still emissions compliant later in its life). OBD2 is planned for 2020, when the bike will be required to self-diagnose and self-correct to maintain its emissions control throughout its lifetime.

Which bikes are affected?

Euro 4 affects all new models introduced in 2016, and all new bikes from 2017. So, for example, the new Honda Africa Twin, new Suzuki GSX-R1000 and Yamaha MT-10 are all Euro 4 compliant, and by 2017 all existing new bikes will have to be too. Some models already are, because similar emissions requirements to Euro 4, including the evaporative emissions test, have been in force in California for several years.

Besides, manufacturers are well aware Euro 4 has been coming and know the even harsher Euro 5 regs are only a few years away, so they’ve had time to adapt their existing engines (where feasible) or design new ones that comply with the regs (in 2005, Euro 3 was widely accepted as the reason for the death of Suzuki’s air-cooled GSX1400, but it didn’t seem to affect Yamaha’s equally air-cooled XJR1300, still on sale today… although don’t expect it to survive beyond next year).

Some use more obvious technology than others; Ducati’s Multistrada and XDiavel have variable valve timing to help achieve more efficient combustion across a wide rev range. But it has other benefits besides emissions (power delivery, flexibility etc) and so while it helps, it’s not necessary to get through Euro 4.

Ducati’s new 959 Panigale gained a capacity hike mainly to offset the effects of Euro 4 on the old 899’s performance. And Euro 4 hasn’t stopped Triumph’s new Bonnevilles steadfastly maintaining an air-cooled look (even if they’re fully water-cooled underneath). They might not be the most powerful engines in the world, but they show how it’s possible to design a modern power plant that both meets Euro 4 (and Euro 5) standards yet doesn’t look like the inside of a Transformer’s pancreas.

In the end, the reality is the owner of a Euro 4 bike will likely no more notice which regs his bike conforms to than any other – it’s possible the biggest difference will be how his garage no longer smells of petrol every morning. Euro 4 won’t automatically make a bike noticeably heavier, snatchier, harsher or more expensive than it was before. Finding innovative engineering solutions to market rules and regulations, not to mention within cost constraints, has always been in the job description of your average bike engine designer. It’s what they do, even if they don’t always get it right. If a new bike is uglier, heavier, harsher or snatchier than its predecessor, blame the manufacturer as much as the bureaucrat in Brussels. Because the one thing Euro 4 does mean is that your new bike will almost certainly be more fuel efficient, and will be doing less damage to the planet.

Emissions regulations through the years

  Euro 1 Euro 2 Euro 3 Euro 4 Euro 5
Year 1999 2005 2007 2016 2020
CO 13.0g/km 5.5g/km 2.0g/km 1.14g/km 1.00g/km
Hydrocarbons 3.0g/km 1.0g/km 0.3g/km 0.17g/km 0.10g/km
NOx 0.3g/km 0.3g/km 0.15g/km 0.09g/km 0.06g/km
SHED test n/a n/a n/a yes yes
Onboard diagnostics no no no yes (OBD1) yes (OBD2)
Durability test n/a n/a n/a 20,000km Lifetime

Despite the ever stricter emissions regulations, we’re still getting some pretty good bikes for 2017.

Obviously all the completely new bikes, such as the eagerly anticipated new Honda Fireblade, Suzuki GSX-R1000 and Triumph Bonneville Bobber will be completely Euro 4 compliant.

But even models which look exactly the same as their outgoing relations will meet the new regulations, such as the KTM 1290 Super Adventure, now known as the 1290 Super Adventure T.

Words: Simon Hargreaves