THE PROBLEM WITH PETROL
Modern fuel is an evil brew that can cause havoc, especially if your bike isn’t ridden regularly. And the situation is going to get worse. But there are things you can do…
Modern fuel is an evil brew, but there are solutions to every problem…
THE PROBLEMS
Stories about problems caused by modern fuel are legion. Issues include poor starting, corrosion and failure of fuel system components, and distortion of plastic fuel tanks. ‘The effects are particularly bad on older bikes with carbs,’ says Wheels Motorcycles technician Gary Hurd. ‘But fuel-injected bikes aren’t immune. Ethanol can rot fuel pipes in the tank – it’s worse on older Ducatis and Aprilias with rubber pipes that disintegrate inside the tank – the Japanese tend to use metal. This debris gets into the fuel. Ethanol also destroys rubber seals and fuel pumps – all costly fixes.’ And there’s more: ‘Plastic tanks gradually swell and so can be difficult to refit,’ says independent Triumph mechanic Chris Jagger. ‘And if a bike is left standing injectors can gum up.’
THE REASONS
Since 2010 the Renewable Transport Fuel Obligation has required 5% of road fuel from major distributors (selling 450,000-plus litres per year) to be produced from renewable sources. In April 2018 this was raised to 7.25%. The most common source of renewable fuel is bio-ethanol, an alcohol derived from crops such as corn. Bio-ethanol is hygroscopic, i.e. it absorbs water. When it reaches saturation point the water separates from the fuel and this is when it becomes problematic.
Starting problems are usually caused by the absorption of water. Water is heavier than fuel, so it falls to the bottom of the tank. When you come to start the bike that water will be either picked up by the fuel pump or travel through the fuel tap into the engine and, of course, it won’t ignite.
Fuel breakdown occurs through oxidisation. When fuel oxidises it breaks down into the nasty gloop you find in the bottom of carb floatbowls and clogs jets. Left longer than 6-9 months this gloop becomes a hard to remove varnish. How quickly fuel goes off depends on how a bike is stored. Half a tank of fuel stored in a humid or damp environment will go off quicker than a brimmed tank in a dry environment. Worst case scenario: fuel can start to go in a couple of months. Best case: it could be good for six months plus.
THE SOLUTIONS
If you ride your bike regularly, you shouldn’t have issues. Ethanol-enriched fuel is at its worst and most destructive when it’s sat in an unused bike, so the best way to avoid issues is to get out there and ride. You can buy ethanol-free fuel at the pump, but only certain brands (Esso Synergy Supreme + for one) and only in specific areas of the country. In other words, it’s a lottery. Super Unleaded has a higher octane rating than normal unleaded (97 compared with 95). That means a better burn and more performance, although gains are minimal and mpg will be about the same. Personally, I always use Super in my bikes, especially 2Ts, because if I’m going to put something in the tank I might as well use the best I can. But even then I don’t want it to hang around long enough in a bike’s fuel system to cause issues. If you’ve got a bike with running issues it’s worth draining the fuel tank (and float bowls if it’s got carbs) and checking for water in the petrol – you may find as much as 10% of the volume of what comes out is water.
STORING BIKES
If you do store a bike, drain the fuel system before you lay the bike up. On a bike with carbs and a fuel tap let it run until all fuel in carbs has been burnt. Then either brim the tank so there is no room for condensation to accumulate, or empty it and spray the inside with GT85 or similar to prevent rust (if it’s a plastic tank, drain it). Store the bike in a dry place and use fresh fuel on start up.
Another option is to use fuel stabilisers such as Silkolene pro FST and Liqui Moly to help slow oxidisation. Manufacturers also claim their products protect against rust and corrosion within the fuel system (this is more likely a by-product of the fact it slows the hygroscopic process), and also lubricates valves and valve seats. Most fuel additives contain lubricant of some sort so there could be truth to the latter claim.
Stabilisers should only be added to fresh fuel because they can’t turn ‘bad’ fuel into ‘good’ fuel, i.e. they can’t reverse the process of chemical breakdown within fuel, only slow it. Stabilisers are pointless for day-to-day use. But, if you’re storing a bike for several months stabilisers do have merit.
ALTERNATIVELY
The ‘simple’ solution is to remove the ethanol from your petrol, or use fuel free of the stuff at the point of sale. Ethanol removal kits are available such as Ethanil from classic-oils.net. The standard kit costs £49.95 and can produce up to 17 litres of ethanol-free fuel at a time. Obviously, you’ll have to process the fuel before putting it in your bike, costing you time, hassle and cash up front. There’s a risk too. Removing ethanol from fuel can take away the ‘light ends’. These highly ignitable elements promote combustion and without them you will be down on performance.
If you don’t fancy becoming a fuel alchemist you can buy ethanol-free fuel. Recently formed company Classic Fuel Solutions sell ethanol-free 100 octane petrol in 20 litre barrels and can deliver it to your door. ‘It’ll stay good for three to five years if stored correctly,’ reckons CFS’S Chris Hatherall. But at £2.16 per litre (plus delivery) it isn’t cheap (average UK pump unleaded is currently £1.28.8 per litre).
THE FUTURE
Reducing carbon emissions will increase the pressure on fossil fuel use, and bio-fuel is likely to become more prevalent. However, cries of indignation from the motor world (loudest from owners of older vehicles) mean E10, the proposal to increase the bio ratio in fuel to 10 per cent, has been held back. For now anyway. Manufacturers are already on the ball. ‘We’ve been geared up for E10 since 2011,’ a spokesperson for Kawasaki UK told Bike. ‘In practice that’s meant building bikes with fuel systems resistant to ethanol. Bio-fuel produces less power and inferior fuel economy compared with fossil fuel, but for new bikes with fuel-injection and ECUS it’s not a problem. Old bikes are the worst affected.’
‘The ‘simple’ solution is to remove the ethanol from your petrol’