Okay, I'm a little confused about exactly when hydrolock happens to a bike dumped in water. It seems that there are many stories where bikes are dropped in very high water and survive unscathed. I'm picturing most bikes just getting choked out by the water (shutting down the engine) before hydrolock occurs. I imagine hydrolock occurs when the rider is WOT at the moment when water enters the cylinder. That the piston has loads of momentum at this point and doesn't "slow down" once the ignition sequence has been choked off due to lack of air. The piston, with loads of momentum, then tries to compress the water; which ain't happening. Is this all basically correct? What are "the rules" when it comes to dropping a bike in water and living to tell the tale?
I think wheel bearings are typically ignored. Many bikes currently produced do NOT have what would be known as "sealed" wheel bearings. Yet people think it's cool to water cross. Bearings suck to change trail-side.
The first thing you should do is study the difference between 2 and 4 stroke engines, unless only one or the other interests you. You will see that 2 strokes are much more susceptible to damage from hydraulic locking.
I dont know why you would think that,both 2 and 4 stroke have a compression cycle,if there's water that wont compress the rod gets bent and the crank bearings can get squashed. A friend tipped his 1150GS over in water and it did 2500 in damage in a heart beat. The thing is on most 4 strokes,they will have water in the oil the rest of the day,cant drain all the oil out and oil goes through trans and engine both,enough water will foam the oil and so much for that engine. A 2 stroke of course has separate trans oil. As does a Beemer and my 530KTM,but the oil keeps circulating whereas a 2 stroke gets new engine oil with the gas. The trick is to realize when all is lost and hit the kill button,if its deep water and a good chance of going down with the ship have a finger poised over the kill button. Better to push it out then destroy the engine. I recently put my 200KTM underwater briefly,pipe full,carb full,air filter/airbox full,engine sucked water. It was on it's side for maybe 2 seconds at most. But in about 45 minutes the 3 of us had it up and running fine again,it was clean water,no harm done that I can tell. Having a towel to blot the airfilter was priceless,rolling the bike upside down and rolling it sideways seemed to get the water out of the pipe and engine. Pulling the plug and pumping the kicker with bike upside down,the usual. Drain floatbowl,start bike with air filter out,once running re-install it and off you go into the wild blue yonder. If these tricks arent used,and worse yet you try to start the bike when you know its full of water,then the day can go very bad.
The wheel bearings dont usually hydro-lock.........Yeah they get ruined if the seals are worn out but they dont die on the spot. Once you get home they can be replaced. Its not that its "cool" to cross water,its a part of trail riding unless you want to turn around at every wet obstackle. Doing water crossings for fun isnt bright.
Back when I was a kid I tipped over my XR500 while crossing a beaver dam. The bike and I both went in and completely underwater. After a few interesting seconds of sheer terror while I thought I might actually be trapped under that beast I managed to get to the surface and with the help of a friend pull the bike out. We flipped it over, pulled the plug and air filter, and then kicked it over a few times to get the water out. Put a spare plug I had in (it was the drier of the two), replaced the filter and it started with a few kicks. We rode the rest of the day. I never had an issue as long as I owed the bike.
Well I guess if a person had a degree in probability and statistics and looked at it, it would be twice as likely
When you get home and find a crawfish in your airbox you have done it right. That actually happened to me one of the many times I lost a bike in the water. That was 25 years ago and I have yet to live that one down. I think the old boy was under the seat and crawled in after we wrung out the filter trailside. But he was in there. But as for the actual drowning I think they generally stall before they self destruct. I have never done anything special on any of my crash dives. Yet none of those U-boat adventures caused any long term harm. I finished every ride that I drowned a bike on. My XT350 was lost in 6' of water with the paper dealer tag on it and it ran for another 15 or so years. To me, the bigger issue isn't what you do trailside that matters but what you do when you get home. Trail water crossings are generally pretty silty. So I always flushed the motor several times with kerosene and cheap oil afterward. There are pros and cons to the kerosene fkush. I did it to get a lot through the motor for flushing before doing several oil changes with cheap oil. Then you undo and blast every electrical connection on the bike with WD40.
I should have specified single cylinder. A 2 stroke has 2 compression strokes and like a multi cylindered 4 stroke can deliver a power stroke against a hydraulically blocked piston.
Really useful information there. A couple of weeks ago a friend invited his buddy who was visiting from Colorado on a backroad ride with us, on his Ural. At one point, he had a mighty bow wave coming off the front of the bike, but his air cleaner was too low and it drowned. Needless to say, we didn't tip that one over to get the water out! We did get it running, eventually.
Well the 2 stroke would need to be multi cylindered too then. Or do you mean the cylinder/power stroke is working against a hydrolocked crank chamber? I doubt at that point there would be anything close to ignitable inside the cylinder... and the crank chamber would need to be very full... I can't see that happening. And what would break in that scenario ? Reed valves ? I know hydrolock can happen, but don't see why 2 stroke would be more prone to damage. If anything, a 2 stroke is less prone to damage. Since 2/4 stroke engine can't ignite water !! It is the flywheel and crank weight/mass spinning and working against a hydrolocked cylinder destroying the conrod. And 2 strokes tend to have lighter flywheels than 4 stroke thumpers... sooo..
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Me (and/or my son and wife) have submarined a bike probably a dozen times; both 2 stroke and 4. I've always got them running and ride them back to the truck or shop to change the oil, clean and re-oil the filter, etc. I never worried too much about wheel bearings since I regrease them regularly as part of regular maintenance. I certainly wouldn't replace wheel bearings every time we got the axle underwater or I'd have been doing them every weekend. Dave