gas tank empty..it was all in my motor?

[bob_me]

So I went to hop on my scoot, and started her up and it sounded unusually crispy. Then it died. I thought it was out of gas, which it was. I had just put a full tank in the day before so I was confused. I also, the other day got some oil to do an oil change. So I decided to change the oil for the hell of it. When I cracked the bolt and got it all the way of a tidal wave came pouring out and almost took two of my cars down the street! (Minor exaggeration). The entire content of my gas tank had resurfaced....wtf? So I read a few posts on here about petcock being the issue possibly. Mine is some aftermarket deal the guy who owned previously had put on..doesn't have prime or any other settings. Just on and off. But its never done this before and I always leave my gas on.
Can anyone help? Here's a pic of petcock

 

[bob_me]

Is there any other questions I should be asking? Seems a few people have read this thread but no answers?
I want to go ride right now,but Dont want to risk putting more gas in until I know what the problem is.
Thanks in advance

 

[DaveO]

A carburettor requires a supply of petrol held in a small reservoir which has constant level. This is so the petrol is at constant level with the jet/jets.

Take a look at the bottom of the carburettor. The bowl is where this pool of petrol sits.

The level is held constant by a float which falls with the level of the petrol allowing more in, and rises to close off a small spring-loaded valve (shutting off the supply) when the level has risen back to the proper level.

If the valve isn't working properly the flow may not be shut off. A small amount of muck or general wear may prevent this. This is what has happened. The small valve has become jammed and the petrol has filled the bowls and flowed down the inlet, onto the pistons and probably seeped past the rings into the sump.

You need to search instructions on how to rebuild this valve. (Cleaning may be enough). Fit a fuel filter of some sort afterwards.

Try changing your oil and trying it out. It may be a one off caused by a bit of muck (which has now been washed away.)

Hope this helps

Dave.

 

[DaveO]

Here's a thread on it http://www.xs650.com/forum/showthread.php?t=26530&highlight=float+valves+rebuild

Oh, by the way. I forgot to mention. If the floats are leaking they will sink and also prevent the valve being closed off.

 

[bob_me]

Thank you very much, the carbs are off and I was just awaiting a response before I attacked it. The float valve makes perfect sense. I'm hoping a cleaning will do the trick

 

[DaveO]

See the comment by Angus67 (in the thread supplied). "tapped it with a screwdriver .. all good".

It might just be a bit of rust from your tank holding the valve off its seat.

If you have a special it probably has a simple tap from a custom tank and straight into the carb. Nice and clean looking but bound to cause problems down the line. The standard tank has a filter built into the tap. You'll get it sorted.

Dave

 

[cra-z1]

That valve is something you can find on a lot of commercial oil or gas lines. It's a plug valve. It will work but with any manual valve you should always turn off the gas at the tank.

 

[nj1639]

Yes, don't depend on your floats to stop the flow.
Turn the petcock off when you're done riding or have the engine shut off. Old school 101.

 

[angus67]

Turn the gas off when your engine isn't running. You've got a couple gallons of liquid being held back by a tiny valve. That ball valve would stop 250 gallons from going anywhere. I have one on my emergency shut off for my house furnace oil tank.
And yes, tapping it with the handle of a screwdriver fixes it at the moment, but isn't in the manual. Im my case, I hadn't put a filter inline, it was a shakedown after carb sync.

 

[angus67]

double post

 

[weekendrider]

Slightly conically tapered metal (often brass) plug valves are often used as simple shut-off valves in household natural gas lines.
Put a proper fuel valve in.

 

[gggGary]

The good news is ALL the gas had drained out. If there had been enough gas left in the tank for the engine to keep running you would have destroyed it. Just a matter of which disaster would have happened first, cylinders, bearings, hydrolock. I hope you will use the petcock from now on.

 

[bob_me]

Yes absolutely , I didn't put that brass contraption on there but it will not be going back on. Thanks for the input. I have tapped the carbs with a screwdriver before on my quad, it worked, but on my bike, I figured I better just hop in and see what's wrong. So I couldve blown my motor huh? It ran for a good two minutes, nothing sounded bad like rings frying or anything? However, my ears wouldn't be that sophisticated as to hear that maybe? But glad to know. I just put two quarts of motorcycle oil in, and tomorrow will throw it back together (with new petcock) and see how she rides.

 

[fredintoon]

Hi bob,
what amazes me is that the engine started at all with that much fluid in it's crankcase but your engine would have survived a longer run just fine; 2-strokes run all day on 50-1 mix and your engine was running on 5-1, eh?
Woulda most likely wrecked a plain bearing engine but not a roller and ball one.
Certainly clean the carbs, change the gas tap if you must but more importantly, change your habits.
Turn the gas OFF when you park.

 

[CDNTX650]

Yup...next time it could end up on the floor in a huge puddle waiting for an ignition source.

 

[richardthemotorcycle1]

First that's an inline fuel valve and not a petcock, those require you to shot off when not using scooter. Does that run with a gravity fed fuel line, or does it run on vacuum?

 

[fredintoon]

First that's an inline fuel valve and not a petcock, those require you to shot off when not using scooter. Does that run with a gravity fed fuel line, or does it run on vacuum?

Hi richard,
fuel valve, petcock, or even benzinenhahn, unless they are vacuum-operated and NOT set to "prime" you gotta shut it off yourself, eh?

 

[weekendrider]

All fuel(for the xs) is gravity fed. The vacuum operates the valve(diaphram) in the petcock.
Now someone can post where a fuel pump system has been adapted to an XS.

 

[richardthemotorcycle1]

That is so true fredintoon, I use to own a scooter(mine was vacuum) that's why I said that, but you are right.

 

[peanut]

Slightly conically tapered metal (often brass) plug valves are often used as simple shut-off valves in household natural gas lines.
Put a proper fuel valve in.

exactly my first thought WE 'thats a valve to turn off the gas supply to a gasfire

This is what I'm going to fit to my 79 2FO . I don't like the idea of all that 'gas' ending up in my sump