With all of the recent heavy rain that a large portion of the US seems to have been getting lately, now seem like an appropriate time to talk about deep water crossings. Actually, we'll jump ahead this month and first discuss what you need to do should you miscalculate your attempted crossing and submerge your machine.
If possible try to get your bike out of the water and onto dry land, or if that is not possible, (like the situation I got myself in a few weeks ago!) try to get to shallow water. Water has far more chance of drowning out your engine by entering through the air filter than through the exhaust. If you are uncertain as to whether you drowned out your engine, always try to start it first. If you did a good (bad!) job with the deep water plunge, then the cylinder will have enough water in it that it won't be able to turn over due to being compression locked. If that is the case, don't try to force the piston through the stroke any further as this could lead to catastrophic engine damage such as a bent connecting rod. If there is only a small amount of water present in the cylinder, then the engine will most likely still turn over but definitely will not fire. When this is the case, the engine has a hollow, muffled sound to it when trying to start.
Begin with taking the air filter out, wring as much water out as possible by squeezing it and then place it down out of the way while you work with undrowning the rest of the bike. It is usually best and easiest to have removed the seat and tank to do this. Take the spark plug out and then turn the bike upside down with both wheels straight up in the air while it rests on the handlebars and the top of the back mudguard. If you are out on the trail by yourself, the most efficient way of flipping the bike is to lay it over first and then place one hand on the front wheel with the other on the frame rail under the engine case. While lifting, try to not let the bars turn on the ground.
Once upside down, go ahead and place the bike in top gear using the shift lever and then aggressively spin the rear tire with your hands for approximately one minute so as to pump all of the unwanted water out of the engine. Then, flip the bike back upright again being careful not to let any water back in through the airboot (like what happened to me recently!) if you weren't able to secure dry land for this procedure. Now, blow any remaining water beads off the spark plug and then re-install it.
Now it's time to move the carburetor over. Simply loosen the airboot clamps and spin the carb sideways if possible and remove the drain plug on the float bowl. Empty the drain plug and blow it out. Before re-installing the plug, make sure you place the carb back upright and allow a little fuel to flow through it to flush any remaining water out. With the carb reassembled and tight, place the fuel tank back on the bike and hook up the fuel line. You don't want to reassemble the whole bike until it is running again.
Go ahead and start the bike now just like you did the first time that morning; fuel and choke on, no throttle while giving a big, solid kick (modern four strokes with a pumper carb could do with a quick pump or two of the throttle before kicking though). Bang! She should fire up definitely within the first 3 kicks. Once running (pretty rough at first) just let the engine idle itself clear before giving it quite a few big revs to clear it fully out. Usually if it doesn't fire after about ten kicks that means there is most likely some water still remaining in the engine/carb, therefore you will need to repeat the above procedures again.
While the bike is still running re-install the air filter, seat and bolts, tightening to the appropriate tension. With some experience you should be able to be back out roosting on the trail in under 10 minutes. Woohoo!
Next month we'll talk about techniques you can use while crossing the deep blue to help avoid the above situation. Also, in the not to distant future, we'll be releasing the remaining volumes in our new series of DirtWise Advanced Instructional DVDs that will show all of these techniques and many more in action. Visit www.shanewatts.com for more info.
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