April showers bring May flowers… along with flooded trails and water crossings which lead to drowned bikes. Many riders do not think about what to do if they flood their bike until after it has become a submarine; do not be one of those people. I have become familiar with the process, having resurrected somewhere around ten bikes now, and I'd like to share my wisdom with you.
• Don’t drown your bike in the first place
The best advice is to simply avoid drowning your bike in the first place (helpful, I know). Your bike will run with the exhaust submerged but it will cause it to bog; adding some throttle to prevent stalling will keep you underway. This mostly pertains to adventure bikes with low slung exhausts, but you would be surprised how deep you can take a DRZ before enough water gets into the airbox to kill it.
Things are starting to go wrong for Brad here. Some quick thinking can save a lot of trouble.
• Do kill your engine before it takes on water
Lets say you couldn’t resist the water crossing and something went wrong: the bike is going down! Try to kill the engine before it sucks the water in. Water is essentially incompressible, so you do not want your motor attempting to compress it; something must give, and it won’t be the water.
• Don’t try to immediately start the bike
Likewise, you must refrain the irresistible urge to immediately thumb the starter after retrieving your bike out of the water. Push your bike back to dry land to assess the situation before making any attempts to start lest you risk costly motor damage. Yes, many people ignore this step and avoid catastrophic failure, but in this case it is better to be safe than sorry. I have seen very few cases of bent rods, but many cases of bikes burning excessive oil after cranking a motor filled with water.
This bike was submerged for over a minute allowing it to take on serious amounts of water.
• Do check the air filter and airbox for dampness
The best place to start is to open your airbox and check if the air filter is wet. If you took only a quick splash in a shallow creek you may get lucky and find a dry filter and airbox: go head and fire it up. For the not so lucky it is time to pull the filter and start drying it. Wring the filter the best you can and let it sit in the sun while you continue onward with unflooding the bike.
Improvised attempt at draining water from the throttle bodies and cylinders.
• Do remove water from the crankcase
If you believe the bike has taken on significant amount of water, such as if it was completely submerged, then it is likely that your crankcase is filled with water. Check your sight glass to glean some information: if you managed to shut off your motor before taking a swim there is a good chance the oil and water are separated, if not it will look like your motor is filled with chocolate milk. Likewise, you can remove your oil fill cap to check is the case is now filled to the brim. If it is filled with water (or a nasty milkshake mix) you will want to address that first. If you are lucky (or patient) the oil and water will separate with the oil rising to the top; this will allow you to open your drain bolt, drain the water, and immediately plug it as soon as you see oil come out. If your motor has mixed up the oil and water, it is likely to stay that way and you really should flush the mixture and fill with fresh oil before continuing but sometimes you have to do what you have to do to get back to civilization.
Time to pull the plugs before turning the motor over.
• Don’t crank the motor with the spark plug(s) in yet
Remove the spark plug(s) before attempting to turn the motor over. Even though you drained the water from the crankcase there will still be some water in the cylinder(s); remember that water is incompressible thing we talked about? With the spark plug(s) removed turn the motor over until you no longer see water being expelled, then hold a rag or piece of cloth over the plug hole and turn it over more to see if it is still spraying a mist. Once you are sure no more water vapor is spraying reinstall the plugs after drying them first. With a dry air filter and dry plug(s) installed, and water removed from the crankcase, you are finally ready to start the bike and continue on your way!
• Do flush your oil again when you get home
Be sure to flush and replace the oil when you get home as it will continue to mix with the residual water inside the motor. Start the bike and let it get warm or go for a short ride and check oil condition again: if the oil looks milky you need to flush it again. Repeat this until the oil looks a normal consistency.
Carrying the tools to revive your bike can be crucial when off the beaten path.
• Don’t leave home without tools and a plan
Depending on the bike, and how much water it took on, it can be a two-minute process (2-stroke dirt bike) or two plus hours (multi-cylinder ADV bike) to get going again so be sure to have a plan before hitting the trails or going on an adventure. For example, I carry oil, spark plugs, and all the tools I need to work on the bike when I go on multi-day adventure rides in remote places so that I can continue on when I drown my bike, however, if I drown my dirt bike on a typical trail ride my plan usually consists of pushing it back to somewhere accessible by truck so that I can grab my tools or just take it home to work on. Over the years I have stopped to help several riders who were unsuccessful in enacting their plan of “don’t drown the bike” and had neither the knowledge or tools with them to save themselves from being stranded.
Have fun blasting those water crossings without fear!