There is a lot of fuel from the petcock to the actual cylinders. I know this because I read on here that hydro lock could be a problem so when I first got the bike I turned off the gas every time I shut off the bike. I would forget and I was probably getting close to a mile away from house before the bike started running out of gas and I would turn the petcock on real fast. I'll go measure the distance just because I know exactly where I would start running out. Same spot every time.
End result is, I don't turn the gas off any more because I think that I would have hydro lock if I was going to have it whether I turned the gas off or not. Seems to be enough gas in the lines to cause hydro lock but with out the gas tank involved you would have less pressure on the gas.
I would guess the floats are the problem. ????
Someone made a great point about fuel line leakage etc. just a while ago. If the petcock is good (actually shuts off) and it is closed the fuelin the line should be held there - remember when you were a kid an would suck on the straw and then put your tongue on the end and the liquid would hold in the straw?? As long as air can't get in the gas in the fuel line should hang there.
Perhaps the "proverbial" side stand low side fill is created when you have two bad float valves one on the high side and one on the low side?? Air COULD get in via the high side from the bowl vent then past the float valve and allow the fuel to run out the low side.
Hydo= hydraulic = liquid, the "lock" is created because liquids for the most part will not compress under pressure - opposed to gases. The "clunk is when the engine comes up against the liquid in the cylinder with both valves closed (compression stroke) following the intake stroke when the intake valve is opened and the will allow any fuel that has been dripping from the overfilled carb bowl into the cylinder.
Maximum cylinder volume is 253CC., compression ratio is 9.8:1 so it closes down to 25.8CC =1.74 US table spoons (1.45 Imperial tablespoons for the Canadians and Brits). This is the amount of fuel it takes to fill the cylinder at TDC, so basically 2 tablespoons, less than an ounce (the small US ones) will lock the engine.
So "if" the stars line up. AND you have a source of fuel when the engine is stopped - perhaps an unsealed petcock. One or more float valves that for some reason are not sealing and stopping flow into the carb bowl - bad float, buildup on valve seat, worn seal, sticky needle or some other phenomenon. You are a candidate for the expense of hydraulic lock.
Other factors such as use and whether the bike has been laid up for an extended period of time, storage practises, source of fuel and cleanliness, ethanol is a bitch, etc. can all come into play.
I personally have been lucky and caught it twice before causing any real damage. This spring I started mybike after a 4 year layup and had poor float valve seating on 3 carbs intermittently. I finally got them to seal after have one bowls off several times with the carbs out. Cleaned the jets and float valves and then had a bowl leak. Used an elevated full source to put more head pressure on the float valves and eventually got confidence in them. Been running cleaner with my gas and it seems to be smoothing out.
