Updated June 2022
For most of us, once we decide to adapt our bikes for a really long trip, the first thing we think is: we’re gonna need a bigger tank. Below I expand widely on the options as printed in AMH8). Feel free to add your ideas and solutions to the comments below.
Image below: world fuel prices at the date of update from this regularly updated source (just before Ukrainian invasion spike). The cost of crossing some countries will vary greatly, and at some borders it pays to arrive either near-empty or near full.
How much range?
Having done my share of riding in remote areas, in my opinion on a bike a maximum potential range of 250 miles or 400km is ideal. There will be very few occasions when you’ll need more, and at that time a temporary solution (see below) will do the trick.
As it is, the proliferation of car ownership across the developing world has seen a commensurate increase in fuel stations compared to when I first starting travelling by bike. Most of the time half that recommended range will get you to the next servo.
The simplest way to maximise your range is of course to ride economically and/or choose an economical machine. In my experience any bike ridden at around 55mph/90kph will return optimal fuel consumption. Experienced overlanders will know that local driving standards and road surfaces being what they are, 60mph is usually a practical top speed out in the AMZ.
On the right, a conversion table for those of you who don’t speak UKmpg or kpl. Click link for readable version to download
Riding economically on an injected 660Z Tenere (left) one night in Morocco I got a record 86.8mpg, which included crossing the High Atlas. On an F650GS and later, a 700GS twin the best was 80. With a CRF250L I topped out at 98.5, on my CB500X it was 93.5mpg. I got the same from the G310GS. My Himalayan did 78mpg but on an Africa Twin in the same area the best I managed was 64 mpg. A Honda NC750 is made to save fuel and sure enough, I averaged high 80s mpg over a month without really trying.
These are all impressive figures compared to the bikes I rode in the 80s and it’s mostly because they all use fuel injection. Added with other advances in motorcycle engine technology, electronic fuel injection is far more efficient, less fussy and more reliable than a carburettor, and it continues to improve year by year.
Of course trundling along at 55mph, saving the planet for your children and your children’s children can get frustrating on a Triumph Tiger 900 Rally, if not outright unnerving on a busy, fast road. One of the pleasures of quiet backroads is that you can ride your bike at its own natural pace without other vehicles breathing down your neck or getting in your way.
Other ways of saving fuel include running smooth tread-pattern road tyres at maximum recommenced pressures, as well as minimising the frontal profile of your bike (though this only really matters at higher speeds). Overtake smoothly, brake moderately and generally try to maintain a steady momentum at a smooth pace rather than racing from bend to bend or truck to truck. If you’ve a choice, avoid the lowest octane fuel in a bid to save a few pennies. I’ve found it can be a false economy. It goes without saying that your bike wants to be in good shape with a nicely lubed chain.
When things get desperate – we’ve all been there, tucked in and head on the tank – coast in neutral down long descents while remembering that without engine braking your brakes may overheat on a very long switchback descent. Unless every drop matters, better do this with the engine ticking over in neutral so your lights, ABS and anything else works like it should. Engine on or off, be careful not to knock the bike into gear.
One thing I went through a phase of doing was marking a throttle position marker on the throttle body (left) with so it’s easy to tell at a glance if you’re inadvertently WFO. Tucked behind an effective screen on a powerful bike, it’s not always possible to notice a strong headwind or a gradient and how the throttle has crept open to deal with them. Very often closing the throttle a lot will barely lose you any speed, but saves a whole lot of fuel.
Most 250 road and trail bikes today could return 100mpg. A 125 ought to exceed that by 50% but I believe a 250 is the smallest practical capacity for overland travel once you load it up and add some mountains, traffic and headwinds. What’s interesting is that my 2012 250L (left) cruised at 60mph with little left (especially at altitude), while the CB500X cruised at 70-75 where possible and with more to spare. And yet peak mileage was within 5% and the average was only some 15% better on the CRF (once I retuned the fuel controller).
But crucually, I bet if I’d run my 500 at 250 speeds that gap would have narrowed.
Any 500 (maybe not a Himalayan) is largely immune to gradients, headwinds, loads or your impatience. At times on the 250 I was stuck at 50-55 with nothing left for overtaking which in its way can be tiring.
The 250’s real benefits are clear: lower purchase price and insurance and much lighter weight (reduced shipping costs, easier picking up, less intimidating if not positively inspiring off-road). For a light- or off-road focussed rider a 250 is a great choice for a travel bike. Me, I’d love to see a CRF450L and I’ll keep saying that until they make one. In 2018 they did – oh dear….
• Capacity: 250cc vs 471cc
• Fuel capacity: 7.8L vx 17.5L
• Claimed power: 24hp vs 47hp
• OE wet weight: 146kg vs 197kg
• My cruising speed: 60 vs 70-75mph
• Av. fuel consumption: 86.7mpg vs 74mpg
• OE max fuel range: 140m/270m
Getting up to 93mpg from my CB500X makes me wonder if a 500 may be the goldilocks capacity for an optimal economical bike. In 2018 I did a Moroccan tour with a GS1200LC among the GS310s. Apart from one 200-kph burst, that boxer dawdled along with us at sub 100-kph speeds. The best I recorded from the rider was 65mpg which must be as good as you’ll ever get off a 12LC. An old GS700 covering the same, 1100-km lap at the same low speeds averaged low-80s mpg (68 US; 3.4 l/100km; 29kpl).
Extending your range
When it comes to extending range, most of the time we’re balancing convenience with the cost, weight and bulk of carrying extra fuel. Bulk is a factor on a small bike. Weight matters too if you’re planning on riding on dirt. On the left the KTM790 carries its 20 litres low. And to some cost matters too, but with bigger tanks it pays not to think too hard about capacity increase vs cost because you will always lose. For a long trip it’s more about convenience – knowing you can get from A to B without needing to fill up, even if you do stop frequently anyway to take pictures or smell the roses. Aside from doing all the right things as listed above, here are the options to carry more fuel:
• Fit a bigger aftermarket tank
• Enlarge the OE tank or make a bigger one
• Carry or mount extra fuel containers, rigid or collapsible
• Procure temporary/disposable containers
Fuel sock filters like the Gugatech below, fit into a tank’s screw-on filler mouth, catch crap and even water before it gets to your injectors or carb, and can be easily cleaned.
In Europe Acerbis made their name supplying big plastic for the original Dakar Rally, but really haven’t developed new big tanks in years. In the US you have Clarke and IMS and in Australia Aqualine/Safari serve desert racers who’ve grown into adv riders. There’s also Touratech plus some smaller, specialist outfitters.
But if you can, buy a bike with a useful range in the first place. Anything with more than 15 litres should do and, along with the beak, this is one of the genuinely useful features of your so-called adventure bike, though good fuel range is more common on bigger capacity machines. The R1200GS Adventure came with a 30-litre tank which could return 375 miles/600km at 60mpg.
On the left, my XT600Z in 1985. I got 80mpg one day in Mali, slumped over the tank with a backwind and the shits. With the 30-litre OE tank that could have potentially added up to a staggering 840 clicks or well over 500 miles. And yet that bike weighed under 150kg, unloaded. On that trip I still carried a 10-litre jerry to cross the Sahara where 80mpg would be hard to achieve on the sands.
Once you get over the cost, the best thing with a replacement tank is that it puts the extra bulk in the best place to have a minimum impact on the bike. All you get is a heavier machine when full, but if it’s well designed, you knees won’t be splayed like a gerbil on a dissection table.
Tiny stock tanks are the bane of many bikes like the BMW G650 X bikes and the Husky Terra, or 250 trail bikes like CRF-Ls, WR-Rs and KLX-Ss – these bikes all come with tanks at around 7 litres out of the crate which sure makes for great ‘wet’ weight figures.
You can add the KTM 690/Husky 701 (left; 12.9 litres) to that list. Once 690s were recognised as the ‘new Tenere’ and Rally Raid originally made their name supplying extra capacity tankage. In 2020 Husky brought out the 701LR (below) with extra front tanks adding up to 25 litres making a range of well over 300 miles. Unfortunately the extra £900 they charge pushes the price over ten grand in the UK.
Especially in the UK (most plastic tanks are produced elsewhere) it’s the cost of a bigger tank that can make it hard to justify. Would you pay £500 to double the capacity of your WR250R/X to 14 litres (currently £310 in Ozzie)?
Part of the reason they’re expensive it that it takes a lot of work to design a rotomolded plastic tank to fit a given bike, and they’re only ever going to sell a few hundred. On the left a curvaceous 17-litre tank for a WR250R from IMS. A huge, 250% increase in capacity for a fairly reasonable $400 (plus shipping and taxes). I used one myself and didn’t regret the expense. It was great to know I could roam across the desert for miles and miles.
Enlarge, adapt or make a bigger tank
The mark-ups as mentioned above are what compel riders to find other solutions. In the old days before plastic tanks became road legal in Europe, it was common to get your own metal tank made, or to enlarge the original, very often by simply cutting and welding another on top. It didn’t win any design awards but it got the job done.
Forty years ago for my first desert bike (left), an XT500 (9 litre stock), the only choice was get one made in ally which is easier to fabricate and weld than steel. Others made tanks in fibreglass before kevlar and plastic came along. Alloy doesn’t cope well with the vibration of an XT500 riding over corrugations. Or in my case, that lack of know-how about sturdy tank mounts vs terrain and crude suspension meant the rear mount broke, the loose tank cracked, and it was game over (right) in the middle of nowhere. That’s why I thought the original Tenere XT600Z of 1983 was such a great bike: no need to reinvent the wheel for long-range desert biking.
For some, the 23-litres of the later 3AJ Tenere was not enough. Above, the 3AJ has had a pair of 20-litre jerries morphed onto the tank sides making 40 litres. You’d imagine a potential range of up to a 1000km at 70mpg.
One good thing about enlarging what you have is that you keep the mounts and these days – the fuel pump fitting. It’s not just a hose from the fuel tap to the carb anymore.
Just don’t forget the extra weight on those tank mounts (especially off-road) and, where relevant, the need to keep the level above the main fuel pump or resort to extra lift pump/s to suck from below, as the WR250 IMS tank uses. Efi or carb, fuel pumps don’t use much juice and are easy to replace, so better to suck low than have the mass of the added high, like early Dakar racers (left) or the CG125 (below).
All this faffing about with metal – ferrous or otherwise – is why plastic tanks are such a good idea. They’re immune to vibration fractures, oxidation, magnetic storms, denting and they give a bit on impacts which spares the mounts, all while being easy to repair reliably with glue. And translucent options allow you to see how the fuel level is doing.
Again, in the pre-efi era, you could bodge on any Acerbis that would almost fit as long as the fuel line reached the carb and nothing rubbed. Left, we shoehorned Acerbis XR600 ’40-litre’ Dakar tanks onto our Desert Riders XR650Ls which came with a poxy 11-litre tank (top right).
That still didn’t give us anywhere near the range we needed, so we carried more and buried fuel caches in the desert. I wouldn’t go with all that high up weight again. I’d sooner get 20 litres and 2 x 10 on the side or at the back, but you can see the temptation to get the stuff out of the way in one location.
One tip I learned with the huge tanks on these XRLs: the tank sits midway so upgrade the suspension on both ends to deal with the weight, not just the front. And other riders have found that pressing in concavities on the underside of a plastic tank with a hot spoon can help it fit better or sit lower.
Extra Tanks and Containers
One of the cleverest things about my BMW XCountry (left; av. mpg: 74) was the Xtank made by Erik in NL and mounted opposite the hefty silencer on the right. A simple tube taken from the inadequate 9.5-litre underseat tank’s vacuum (breather) feed sucked fuel from the Xtank into the main tank to create a seamless syphon. Result: the modest range was increased to around 220 miles with no extra pumps or taps needed.
This simple idea is also used by Camel Tanks in Canada and can work with bikes with conventional, over-the-engine tanks, not just a sub-seat tanks. See this post. The Xtank idea is now copied in China (miles cheaper than Camel) so you can adapt a 6L polypropylene side intended for the LHS rear of a CRF250 Rally for under 200 quid. Well worth it. A bit small but see if you can find a 2-litre fuel tank off a Honda GC160 generator. It could mount where tool boxes often go on the LHS.
My message to riders with ununlargeable underseat tanks: consider a similar arrangement for your bike – even with a much cheaper Rotopax or similar (below); it’s such an easy job. Any auxiliary tank that’s permanently mounted but not plumbed in is less useful. If that’s what works, best consider a switched fuel pump into the main tank.
This is by far the cheapest solution. On the KLX, left, with its tiny 7-litre tank, a NoSpill 1.25 US gas can from Walmart (takes 1.5 US or 5.7L) gave me an adequate 200-mile range. I used that can a lot on that trip and the twenty bucks was a lot less than the $275 I could have spent on an IMS tank, gaining only an extra 4.2 litres.
Again on the left, my Funduro in Libya had an Acerbis tank of around 20 litres, but I still needed a red can on the back, and even then, ran out once we drifted into the dunes (picture, top of the page).
On the right, the Reda 1USgal gas can ($30) designed for backswept Harley saddlebags, but here you can see might slot onto a KLX once the seat was trimmed. Giant Loop also suggest it could fit neatly into one of their tank bags. I find this front-of-seat space is often wasted on 250 trailies. Or a real MX bike you’d slide onto the tank like a pro to help the bike carve through berms, but on the trail to Machu Picchu you’re just looking to get there before nightfall without falling off the edge.
In Germany Hunersdorff make lots of handy plastic fuel cans, including Fuel Friends. Touratech sell the wide-mouthed 2- and handled 3-litre cans (right) from £16, as well as pricey mounting brackets for the 2L. Avoid the older ones with the strap retaining thing (arrowed, above left); the filler mouth is annoyingly narrower than a typical fuel bowser pipe. Newer ones as all wide mouth.
The more-rounded three-litre is a bit harder to fix to a flat surface. Fuel Friends also make a 1.5l can (right) with a waisted profile for secure strapping.
The well-known Rotopax series of storage cans (most usefully on a bike: 1US gal, 1.75 (left) and 2 gal – or 3.8 litres, 6.6 and 7.5) are flat slabs that are easier to pack and mount. Kolpin are similar but cheaper and some say less leakproof.
Once full of petrol and shaking about, a flat slab plastic container would ordinarily balloon out, stress the seams and probably burst. That’s why metal jerricans have that ‘X’ in the sides to allow for pressure-reducing bulging. Rotopax and Kolpin got round this limitation in plastic by joining the two slab sides with a central hole, and then using that hole as an ingenious mounting device.
Rotopax especially may cost several times the price of a regular Walmart/Halfords fuel can in a similar size, and for the space they take up, are inefficient, but that doesn’t stop everyone on advrider clamping them all over their rigs.
On the left, a KTM 640 with now rare Acerbis side tank and an Adventure main tank giving a total range of 700-km.
Cheap (or not) plastic cans have pretty much replaced classic steel jerricans on a motorcycle, as is happening with stock fuel tanks. Over the years I’ve used heavy 20-litre and ten-litre jerries to extend my range. The good thing was they were cheap, robust, could be sold on locally, made good bike stands, seats and so on, but they’re heavy and take up room. Above left and right: some smart ways of mounting jerries.
Fuel Bags and Bladders
We now have fuel bags or bladders which take up virtually no space when empty, but being wobbly blobs, can be hard to attach to a bike when bouncing around off-road. Once there’s space up front in the main tank, decant then roll up the bag out of the way.
Emergency ‘go-and-get-fuel’ containers can be the use-once 5-litre Wunderlich bag on the right (€9). Or on the left, the simpler 8-litre Jollytank from Italy made in a similar plastic but reusable. It’s sold on ebay.it from around €6. In my opinion, any fuel bag’s minimal useful volume is around 5 litres or at least 100km.
Rugged vinyl bladders of up to 800,000 litres are made by outfits like Liquid Containment in Australia. On the left, an older 10-litre LC bladder with an integrated spout. I’ve used it on Morocco trips rolled up behind the rack. Never needed it yet but sure glad it’s there. LC’s current versions hold from 2 to 15 litres.
There are Chinese-made copies around, but I’d still take one of these over the same-capacity in Rotopax any day. Watch the rubber o-ring seal doesn’t fall out of the cap, as happened to me on a windy day in Nevada once.
Similar to LC’s bladders is the Desert Fox 3, 6 and 20-litre fuel cell sold in the UK from £49 but with lots of handy lashing points. You do wonder what the actual bladder inside is made of – hopefully something more than a Wunderlich-type thin bag. But it’s all encased in what looks like a tough canvas exterior which ought to protect it, unless the weight of the bike falls on it. The nozzle eliminates the need for a funnel (right) and stores in a pocket alongside the spout.
Giant Loop make the similar Armadillos from 1, 2, 3 or 5 US gallons (3.8, 7.6, 11.3, 19L) but note the warning: ‘Armadillo Bag is not a portable fuel container … [and]… is NOT intended for fuel storage, transport or use as a gas bag in the USA.‘ So disguise it well.
I’ve long used lighter MSR Dromedary bags for water, but this WR guy has used them as fuel bladders on his trip, seemingly without spontaneous combustion.
In dire straits many of us have resorted to using PET drinks bottles or similar, often found by the roadside (right). Like I say in the book, use the slightly more durable fizzy drink ones but don’t expect too much of them and keep them out of a hot sun. They can burst on the slightest jolt so treat them as disposables and dispose of them quickly.
Depends where it happens of course, but running out of fuel can lead to unscripted adventures and memorable encounters. I can’t say I was glad to meet the two sleazy guys who gave me a lift one night in northwest Algeria after my XT500 ran dry. But I got to town and returned next day at 100mph in a local sheikh’s Range Rover!
As we all know, whatever size tank you run, you’ll run out if you misjudge it or push your luck as I did that night. On most other days it’s convenience and peace of mind that a useful fuel range can give to a long ride.