Adv Bike Selection 2

Adventure Bike Selection Myths and Old Wives Tales

In the previous post on bike selection I looked at weight and how it is the single most critical part of adventure motorcycle selection, and how 90% of riders end up with a bike that’s much too heavy for their first real adventure ride into the likes of Siberia or Mongolia. Having debunked the “I need an obese bike” myth, we will look at other adventure bike selection criteria, and see if we can’t debunk a few more adventure bike selection myths.  In particular we are going to look at carbs, fuel injection, reliability, and air cooled vs water cooled engines.

Fuel injection is one of those topics that has the old guard screaming “no no no, never go adventure motorcycling on a fuel injected bike. You can’t rebuild a broken fuel injector or fix the electronic black box (ECU) that drives it in the middle of Mongolia, whereas you can rebuild a carburetor.” And to be fair, they are kinda right with the facts. And yet wrong with their conclusions. Why?

Fuel injection is simply the most simple, reliable and efficient way to get fuel into an engine. Mission critical machines like submarines and single engine light aircraft use fuel injection – demonstrating the extreme reliability of FI as a system for getting fuel into an engine. Those who rail against fuel injection often do so claiming its some sort of new fangled technology. Fuel injection was first used in an aircraft engine in 1902- YES 111 years ago. Fuel Injection is about as modern as the late Queen Mother! Direct injection has been around since 1925. In the second world war, Merlin powered Spitfires were upgraded to fuel injection (under the name Pressure Carburetor) because the engines would cut out in dives and negative G situations (engines cutting out in the middle of a dogfight with an angry fuel injected ME109 on your tail has to be the ultimate benchmark in unreliability). Alfa Romeo developed electronic fuel injection for cars in 1940. Sterling Moss won the F1 season in 1955 in a fuel injected Mercedes. EFI went into mass production automobiles in the US in 1958.

So FI is new? High tech? No.

EFI is many times more reliable than a carb. The failure rate among modern ECUs or actual injectors is near zero. The argument that ECUs can’t be fixed by the side of the road is rendered mute by the complete absence of ECU failures, even on the most brutal of adventure rides. I had a long discussion with adventure motorcycling legend Chris Scott some years ago and despite us racking our brains over an entire pub lunch session, neither of us could recall ever knowing first hand of an ECU failure stopping an adventure bike trip.

As for injector reliability … My previous car was a 1994 V8, in which I racked up 250,000 miles. It had 8 fuel injectors. Not once did I have to touch, service, tweak, adjust, clean or do anything to any one of the injectors that collectively logged two million injector miles. In complete contrast, my cousin has a 1970s car with triple carburetors. Every month he is in the garage balancing his carbs, cleaning the carbs, after just a handful of miles. The idea that his triple carbs could go a quarter of a million miles in perfect balance and reliability without ever being touched is so far removed from reality (and even possibility) that it might as well be in a fairy tale that has the car turning into a pumpkin at midnight.  And yet that level of reliability is absolute reality with EFI.

The fuel injector itself is the pinnacle of simplicity; A system with almost no moving parts. Compare a diagram of a fuel injector with a carburetor (see below) and you will see why the fuel injection requires no maintenance, while the carburetor requires a lot. And if it needs a lot of maintenance, it’s not reliable. Simple.










There are further disadvantages with carburetors. They are gravity fed. They do not operate well at awkward angles. And (in the absence of a fuel pump – which is most cases) they need to have the ALL of the bikes fuel stored higher than the carburetor. Having the fuel high and the carburetor low has two disadvantages for adventure bikes. Firstly the higher than necessary centre of mass that an overlanding fuel load (often 20-30 kgs including the tank) implies when it is located high on the bike rather than low, and secondly a low carburetor, which due to breathing holes means the bikes ability to ford water crossings is very much reduced vs a fuel injected bike which relies on air intake alone as its determinant of fording depth. The ideal design outcome for an adventure motorcycle is to have the fuel low (for weight distribution) and the induction and air intake high (for water fording) … carburetors tend to lead to the exact opposite.

When it comes to motorcycles, there is often one weak link in the fuel injection system, and that is the fuel pump. Some manufacturers do unfortunately have a reputation for putting into the field less than reliable fuel pumps. The flip side to this is that EFI fuel pumps do not need to be vehicle specific as most modern vehicles (bikes or small cars) run similar volume and pressure fuel pumps. That means replacing an EFI fuel pump on the road needs only the location of the nearest auto parts store. Or better still, a reliable car pump can be fitted prior to the journey. In any case, it is hardly a disadvantage over carbs, as I have on several occasions come across bikers broken down in Mongolia and Siberia, needing new parts made for the carburetors. Carb needles, lost jets etc …

Ultimately, I am a believer in empirical evidence as the ultimate determinator of fact vs fiction. As mentioned at the beginning of the article, single engined piston aircraft and helicopters run fuel injection; mission critical applications. So lets look at adventure motorcycles operating in remote areas – areas where you do not want to have breakdowns, and Extreme Siberia is great examples of such remote areas where the consequences of breaking down are far greater than they are in the Dolomites or Eastern Turkey – it’s the closest we adventure bikers get to mission critical requirements. Over 75% of bikes doing the Old Summer Road or BAM Road are fuel injected – and that percentage increases every year. Despite me being in close contact with most of the adventurers to see this part of the world, not once have I heard of a fuel injection related problem during an adventure ride in Extreme Siberia. In the most demanding adventure motorcycling conditions imaginable, EFI and its ECU friend have totally demonstrated their reliability in that challenging environment, across many brands (BMW, KTM, Yamaha).

Further, there are a myriad of benefits from fuel injection. Considerably greater efficiency is one. That not only saves you money, but more importantly for adventure motorcyclists, reduces fuel load and increases range. A fuel injected bike operates trouble free as altitudes vary. In contrast, carbed bikes can get sluggish and run rich at high altitudes, often seeing fuel efficiency drop dramatically, a fuel injected bike actually increases efficiency as altitude increases. Fuel injected bikes are less likely to ping/pink, and can run on lower octane fuel at far higher compression ratios than carbed bikes. Further, fuel injectors are not subject to icing as indeed carburetors are, in cool moist conditions.  Carb icing can occur anywhere above 25% humidity, and between 0 and +25C, as the chart below demonstrates.  In high altitude terrain, the combination of carb icing and rich running multiplies the advantages of fuel injection.

Carburetor Icing chart

All in all, the carb vs EFI debate reminds me of similar arguments from the old guard a few decades ago of points vs CDI ignition. “A CDI is a black box” they yelled. “If it breaks, we can’t service it”. Well time has shown pretty conclusively, that while yes, you can’t really service a CDI box that’s broken, the reality is they don’t break. Therefore it’s a correct point that has absolutely no real world value – just as we see in the EFI vs carb argument.

I have never come across a stranded adventurer with a broken CDI unit, BUT, I have come across a stranded adventurer, stuck in Ulaan Baatar for almost a month, while a replacement distributor rotor had to be shipped out from the UK at great expense. You can’t always fix broken old style parts. They too sometimes need to be shipped out, and as it happens, much more often than computerised control units.


Air Cooled vs Water Cooled:

A similar debate can sometimes be heard from the old guard insisting that air cooled engines are more reliable than water cooled. The logic behind the argument goes along the lines that adding a water pump and a radiator to the bike is an additional system that can go wrong and particularly the radiator is subject to trip-stopping stone damage. The empirical evidence, however, simply doesn’t stack up on that theory. I have done 150,000 km (95,000 miles) on my G650X, a water cooled bike with a very flimsy radiator, and ridden it mainly over some of the most hostile motorcycling terrain on earth; I have dropped the bike at least 50 times, crashed it into rocks at speed, destroyed rims, broken my ribs, bent subframes, twisted swingarms and yet, no radiator problems. My good friend Terry Brown, another veteran adventurer with a similar motorcycle, similarly brutal adventure experience, and running the same radiator, did, after 110,000 km (70,000 miles) finally get a small radiator leak on the BAM Road last year. But it was fixed within 20 minutes with epoxy metal. Between us, over a quarter of a million adventure kilometres (neither of us use the bikes for anything but adventure riding) using a thin, non-durable radiator, and the only problem was a 20 minute delay. Never in my life have I heard of any adventure trip having to be cancelled due to a holed radiator.

On the other side of the coin, the advantages of a water cooled engine are huge. As the engine operates in a much narrower temperature band, the tolerances can be much closer to ideal. The power and efficiency of the engine is much higher. This leads to much lower engine weight for a given amount of power. It leads to much lower fuel consumption (and therefore lower fuel weight needed to be carried) for a given amount of power. There is no reason backed up by real world evidence, to say that air cooled bikes the most logical choice for adventure riding. It’s another great adventure motorcycling myth.

The penalty for choosing air cooled engines is weight … weight of engine required to produce an equivalent amount of power and weight of extra fuel required to offer the same range as the more efficient water cooled EFI engines. In a 60-65 hp bike, the net weight penalty is often going to be 25-40 kgs. An example might be comparing a (66 hp / 66 Nm) KTM 690 engine with a BMW R100 air cooled boxer engine (60 hp / 73 Nm). The KTM engine plus gearbox weighs 39 kgs, vs 70 kgs for the R100 equivalent. The adventuring range offered by 25 litres of fuel on a 690 (65 mpg) would require 38 litres on a R100 (43 mpg). 31 extra kgs in the engine plus 9 kgs extra fuel load … thus the penalty to generate 60-65 hp in an air cooled, carbed bike is 40 kgs. As we mentioned last week, avoiding an overweight bike is the most important rule in adventure bike selection. 40 kgs is often the difference between people loving Mongolia (or the BAM) and struggling miserably with it.

If we look at whats available around the globe in 2013 in terms of deliberately and specifically light bikes, we could compare the 2013 edition of the Honda XR650L with the CCM GP450.  Both potential adventure bikes, specifically designed to be lightweight, both producing around 40-43 hp.  The Honda has a carburetor and air cooling.  The CCM has EFI and water cooling.   As is, the CCM is 130 kgs vs 146 for the Honda.  But that’s not a fair comparison.  The CCM has large fuel tanks and a fairing for adventure travel.  Fit those items to the Honda and the difference is around 20 kgs – plus a few more kgs for the additional fuel load fuel the 650 would need to carry match the range of the EFI 450.  On this basis, you can see that the penalty for using carbs and air cooling, even for a 40-45 hp light adventure bike is still going to be around between 15-25 kgs.

So, in summary: I am NOT telling you that you cant use carbs or air cooled bikes for adventure motorcycling – because of course you can.  There are plenty of guys who have done amazing rides on air cooled carbed bikes. But what I am telling you is that water cooling and EFI is superior – in a myriad of ways.  What I am telling you is a fear or water cooling and EFI is irrational, illogical, adds weight to your bike and reduces flexibility from your adventures.  What I am telling you is don’t listen to anyone who insists air cooled is better for adventure riding – it isn’t. Don’t listen to anyone who insists carburetors are better for adventure riding – they aren’t. By all means, ride air cooled and/or carbed bikes if you like them – I know and respect several guys who do. But none of those guys kid themselves that they are using superior systems. They just happen to like those particular bikes that the air cooling and carbs are attached to, and know they are paying a weight penalty for their choice; a choice which they also know is not one of logic, but one of passion.

The reality is most of the bikes doing tough, challenging, adventure riding in Siberia and Mongolia in 2013 are both water cooled and fuel injected.  It’s time to put to bed, once and for all, prehistoric ideas about cooling and induction that have prejudiced the adventure motorcycling world since those theories were born in the 1980s.

If you are trying to choose a rational logical adventure bike, then you should absolutely be considering fuel injection and water cooling.  In my opinion, it should be the default starting position.  Combined with the weight article last month, that now has me recommending single cylinder bikes, sub 165 kgs dry, preferably with water cooling and EFI.


More of the brutally rationalist Sibirsky Extreme Adventure Bike Selection Guide to come in future weeks …


An interesting post script …

At the end of 1998, the management of BMW’s Motorcycle Division decided to run “boxers” in rallying in order to have a means of comparing two alternative design concepts – The air cooled carbed bike (boxer) vs the water cooled bike (Rotax 650). A well-known specialist company, HPN, was asked to develop a competitive rallying version of the air cooled boxer for BMW as a prototype and fitted it with Bing carburetors. They built the BMW R900RR. It competed in the 1999 Dakar directly against BMWs F650RR.  While the R900RR was developed with factory help and factory money, the F650RR was developed mostly privately.  BMW were putting their own considerable money behind the boxer, in a concerted drive for success for their flagship engine design.

BMW R900RR Boxer
BMW F650RR Single

In rally trim, the R900RR produced 90hp, and weighed 190kg dry. The F650RR produced 75 hp and weighed 168 kgs dry. In absolute power terms, the boxer was superior. In torque terms, the boxer was superior. In power to weight terms, the boxer was superior. The one clear advantage the F650 had going for it was absolute weight. The 22 kg advantage of the F650 (without fuel – even more of an advantage with fuel) helped it win the 1999 Dakar, against its more powerful stablemate, with the boxer ultimately coming in 4th.

The following year, 2000, the two BMW bikes squared off against each other one last time. The old guard represented by the R900RR and the new, by the F650RR. Yet again the F650 proved 1999 was no fluke and again finished ahead of the boxer.  And yet again the F650RR won the Dakar overall.

At that point, faced with the inability of its favoured air cooled engine design to compete with modern water cooled alternatives, BMW effectively gave up on the Dakar. Instead, they shifted all their racing efforts and attention to the Boxer Cup, where BMW could promote their air cooled boxer engine free from water cooled comparisons.

6 thoughts on “Adv Bike Selection 2”

  1. Very interesting read. I actually wish it had been around before i got back into riding. I may well have ended up with a different bike.I bought my DR 650 on the basis of basic is best. No water pump, no fuel pump, no radiator. Doh!!!!. Well i’ve fallen in love with the old girl now so she wont be going to the scrap heap but its a fair bet my next bike will be an EFI water cooled job.
    Thanks for the write up.

  2. Loved the article, but wasn’t the f650RR running the f650 funduro carb motor and not the f650gs efi motor?

  3. Howabout flat batteries? Can you even start an EFI bike, kickstart or bump start, with no juice or fuel pressure?

    Personally I don’t even like being without a kickstart as I’ve come close to flattening my battery many times. Being unable to kick or bump start would, I think, be unacceptable.

  4. To me it boils down to whether or not you are willing to place the reliability of your machine, and ultimately the success of your trip, in the hands of someone else, hoping that nothing goes wrong. Maybe you have no other choice.

    I prefer serviceability over reliability.

    If your serviceable parts are giving you trouble…you deserve it.


Leave a Reply

Your email address will not be published. Required fields are marked *