Motorcycle fording: how do I cross a ford and what should I do if my vehicle has taken on water?

Do you remember when you were a kid and jumped into puddles with both feet? Well, crossing a ford is the same thing, but for adults. But there's a big difference: the risks involved. Wallowing in a river on a motorcycle can be fatal for your engine (and your personal ego). What are the risks? What should you do if your bike takes a tumble? Rest assured, if you follow our few recommendations, this moment will be nothing but fun.

You don't cross a ford just anywhere

Let's face it: crossing a river on a motorcycle is a blast. So, far be it from us to spoil your fun, but these underwater explorations do present a few risks.

The first? A legal one. You can't just ride your bike wherever you want. So, to be able to cross a watercourse, the ford must be specially equipped and clearly signposted. We're not the ones dictating the rules, but the Codever association which does everything in its power to defend our green leisure activities.

Of course, the main risk is mechanical

What do you mean by that? To put it simply, a bike engine is like you and me: it needs to breathe in and out to function properly. And just like you and me, it doesn't work as well when you try to breathe underwater. So, when fording, it's vital to avoid the water level submerging the engine air intake or exhaust outlet. Wallowing miserably in a river is not an option. Not only for your ego, but also for the integrity of your trail bike.

What exactly happens when a motorcycle goes over the edge?

The answer is hydroblocking. Let's get technical. Your engine sucks in air, which is then mixed with petrol to form an explosive cocktail. Problems arise when you replace the air with a liquid. Why do you do this? The reason lies in a simple physical principle: water is incompressible. So, after drinking a cup, your pistons will try to compress a liquid, which is impossible. So most likely, the connecting rod (the metal rod connecting the crankshaft to the piston) will bend under the strain. And if you're lucky, you may also end up with a cracked cylinder head, a damaged cylinder, blown bearings, pulverized crankshaft bearings, etc. In short: your engine is out of action.

You've just wobbled miserably in a stream. You can already hear your fellow adventurers laughing at you in the distance: "It's all very well to have a €20,000 trail bike if you can't ride! Put your ego aside and think carefully. What should you do after taking on water? Leave it in rice for a couple of days, like you do with your phone?

Step 1: Don't restart your bike and get to shore

If the engine has cut itself off during the fall, this means that the water has entered it! Rule number 1? Don't try to restart it! This is crucial. Trying to restart the engine can destroy it. So get your bike up and push it to the bank to get the water out of the engine. Check points? Air filter, exhaust, carburetors, combustion chamber.

Step 2: Inspect your bike and get rid of the water

The first step is to inspect the air filter. If it's wet, your bike has really taken on water. You'll need to remove it, wring it out, dry it and then replace it. Water may also have entered through the exhaust. So you need to drain it. How do you do this? There are two methods. 1, put the bike upright so that gravity can do its job and flush the liquid out of your line. This can be a tricky operation to perform alone on a 260-kilo trail bike. In that case, you'll have to opt for the second option, which involves simply dismantling your line.

Third step: if your wheel is fitted with carburetors, you'll need to drain the tanks.

To do this, you can either open the drain screw, or remove them completely. This 2nd option allows you to inspect what they've been drinking. Is it all gas? Phew. Gasoline and water? Not cool, but not surprising. Mud? You're in for a proper cleaning when you get home.

Step 4: Remove the spark plugs

Depending on the bike model, this operation can be as much a formality as a headache. With the precious spark plugs in hand, dry them. Then, before replacing them, run the engine to evacuate any water in the combustion chamber. How do you power your mill? Either by kicking off, or by pushing the bike into gear (as if starting it from a baby carriage), or by activating the starter motor. In the latter case, be sure to leave the spark plugs in contact with the frame, so that the engine doesn't start idling.

Last step: reassembly

So, to recap? You've drained the water from the air filter, exhaust line, carburetors and combustion chamber. Now it's time to reassemble. Now you can cross your fingers, recite some Druidic incantations and pray to Cthulhu that there's no major damage. That done, turn on the ignition and try to start your bike. Is it running? You can burn a candle and ride home almost untroubled. If it doesn't? All you have to do is call for assistance.

A motorcycle is not designed to be completely immersed in water. So, after your unintentional swim, there are a few things to check, not least the electrical system. After all, electricity and humidity don't mix. In the peaceful atmosphere of your garage, you'll need to check that all the components are working properly (indicators, lights, heated handles, etc.).

Another tip? Water may also have entered the engine oil circuit (via a breather, for example). Spoiler alert: 10w40 lubricates better than river mud. Take a small sample of oil to check its appearance. Is it black? No problem. More of a cappuccino color? That milky look means it's been cut with water. You're due for an oil change. Incidentally, it's a good idea to check the oil color again after replacing it, and inspect the oil again. You never know...

Having said all that, there are a few recommendations to ensure that crossing a ford on a motorcycle is a pleasure rather than a source of stress. What do you want to avoid? Wobbling miserably, of course. But also, to avoid water entering the engine through the exhaust or air intake.

So the first question to ask is: is there an alternative? And yes, if you're not comfortable, you might as well spend some time finding a drier alternative track, ideally with a pontoon.

Opting for crossing?

Find the depth on foot. This will help you gauge the depth and detect any nasty rocks. In fact, a river bed can conceal some pudgy pebbles whose surface is covered in algae. There's no better way to get a good turn.

It's one thing to know how deep the water is. But you also need to know where the air intake is on your bike. So it's important to know the height of your filter. Then take a reference point on your body (kneecap, mid-thigh, etc...) to find out what level of water is tolerable when you spot it on foot.

So much for foreplay. Getting started? Bear in mind that water offers considerable resistance to movement. So it's best to get into a torquey gear at low speed (1st or 2nd gear, depending on the water level). What's more, by standing on your bike, you gain mobility, using your body to its best advantage to counterbalance your bike. So we don't recommend sitting, where you're - with all due respect - dead weight in the saddle.

How fast can you go?

Too slow and you don't have enough inertia. Hitting a rock will destabilize you considerably. Riding too fast will hurt your reflexes. What's more, the splashes created by your front wheel are likely to get in the way. The right response is therefore to drive at a moderate, steady speed, forming a wave at the front of the vehicle. "Surfing on this delicate tidal bore avoids any unexpected infiltration.

Incidentally, while lifting your legs to keep your boots dry may seem like a good idea, it's not. Indeed, it's difficult to maintain good balance if your feet aren't touching the footrests. And this slightly contradicts our recommendation to stand on the bike.

Our final tip?

Keep your thumb on the kill switch. After all, the first thing to do in the event of a fall is to turn off the ignition. You don't want to submerge your bike while the engine is running.

Now you're ready to take on streams, rivers and torrents! The thing to remember? Scouting out your route on foot can save you the trouble of killing your engine. It's an essential step if you're in any doubt. Now that you know all that, all you have to do is plan your next off-road outing. Rando des deux mondes, Gibraltar race, Hard Defi Tour, Ixtem Games: the choice is yours.

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Image credits: motorcycle crash photo by Uralistan; sidecar photo by Uralistan