Possible blown head gasket? 80 1000g

[thebrandonbeezy]

Ok twice in a row now if i let the bike set over night it "hydrolocks" and oil will pore from the air box.. like alot.. soon as i hit the start button itll half rotation and boom lock up. If i put it in gear and bump it back and forth it'll unlock and start up instantly and pur like a kitten.. no misfires no stumble. I have to assume its the original head gasket soo is that possible? Also last time i road it, i felt a mist of oil hit my knees as i got on the throttle... couldn't figure out from where untill now..

[chuck hahn]

Oil wouldnt fill the jugs I wouldnt think. Just no way I can see it migrating UPWARD from the oil pan in an engine thats not running. Im gonna go with its fuel that has dissolved the carbon off the tops of the piston thats coming out.

Take the fuel line and vacuum line off the petcock and make a piece of each size that will go into thier own empty soda bottles. Set the petcock to the ON position and let it set overnight. If the fuel is coming down the vacuum line side of the petcock the vacuum line going to that bottle will let gas into that bottle. Same with the main fuel line side. The reason for seperating the two petcock lines in to their own bottles is to isolate what side of the Petcock is gone.

If either bottle gets gas in it I would be putting on a new one. Skip the known to fail rebuild kits..get OEM new. If neither bottle gets gas in from the petcock test the issue is with the float needles and seats not shutting off the gas. But im betting heavily on a failing petcock.

[gsrick]

What Chuck said makes sense, but I'd ad that you should check the level in the oil site glass and also take sniff in the oil fill and see if it is gassy. If fuel is hydro-locking one of your cylinders, then it's a good bet it's been getting past the rings and into the crankcase also.

BTW both of my 1000s have leaking head gaskets, especially hauling azz. Blown no, bad yes.

[JTGS850GL]

On a side note... NEVER use the starter or roll the bike around in gear if you suspect hydro-lock. Pull the plugs out and then crank the engine to remove the hydro-lock condition or you WILL end up with a bent rod.

[thebrandonbeezy]

Thanks for the advice guys, gonna tinker with it tonight and see whats what..

[thebrandonbeezy]

Just an update guys i guess the petcock is bad, i took the fuel line off and it leakes fuel slowly. Only slightly more than a drip.. now the two times it locked from this were after setting for about a week or so.. been riding it constantly since i made tthis post and its been fine. Float must have been leaking? Ill replace the petcock and give the carbs a quick cleaning

[Kodak]

Not to jack your thread BBeezy, by the way I really hope you go forward with that Arizona Tea Livery you had posted about, but could someone briefly explain what hydrolock is and how it happens in one of our bikes?

[hillsy]

Hydrolock is where the cylinder fills with fuel and wont pass compression as the liquid will not compress like a normal air mix would. Hence the piston will stop but the crank wants to keep moving....which can result in bent / broken connecting rods / pistons....you know - bad stuff

It commonly occurs when either the float valves get stuck open or a vacuum tap starts to leak fuel through the vacuum hose (the fuel goes into the cylinder).

[Steve]

... could someone briefly explain what hydrolock is and how it happens in one of our bikes?

Hydrolock is easy to explain. Your engine is designed to pump AIR (and a little fuel mixed in). I don't know the exact numbers, but let's say that at the top of the compression stroke, the volume of mixture in the combustion chamber is 20cc. If your petcock is leaking and at least 20cc of fuel drips down the hose into the intake runner, when you turn the engine over and that 20+cc of fuel is sitting on top of the piston, it's going to lock up SOLID because the fuel can not be compressed. If the crank has a little bit of inertia behind it, when the piston stops because of the liquid above it, it's easy to bend a rod.

How does it happen? The most common way is a leaky petcock. Probably the next most common is to leave the carbs or the exhaust off the bike and stick it behind the barn, in the rain. Yeah, leaving a spark plug out could also let water in, but if the plug is still out, the water would also go out when the piston came up, assuming it's not rusted into place.

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