I have a major problem on my hands. I have a 150cc L.G. 4-stroke. It had been leaking gas out the overflow of the carb. Constantly, but that problem was fixed about 2 weeks ago with a float level adjustment, and the quad ran fine thereafter. The other day my son rode the thing and ran it out of gas, so I added more and parked it. Well, the next day we tried to crank it and it seemed it was either flooded or the spark plug was filed. So, I got a new spark plug, took the old one out and noticed gas inside the hole for the plug. I tilted the quad over on its side to let the gas out, then installed the new plug. I then attempted to crank it, it almost started up but didn't. Thats when i looked below the quad and noticed black gas coming from the overflow tube of the engine block. I realized there was oil mixed with the gas and instantly took the dipstick/oil cap off to check the oil, and gas spewed out of it. I have completely drained the oil/gas from the oil drain plug, and have done nothing else. Can someone please tell me what you think is wrong with this thing. I and my son are really depressed.

 

I'm gonna guess that you have the GY6 based engine. If so, then you probably have a bad fuel petcock.
These petcocks are vacuum operated and gas should only flow when the engine is running and vacuum
applied to the bottom hose. Does your fuel petcock have two lines?

 

You have a serious problem. First...stop trying to start it.

I will save the bad news for the end.

First thing is to et that petcock fixed. ALWAYS turn your petcock off when not in use. This is one of those bits of manual advice that really needs to be followed. Like Bigric said, you have some kind of problem with the petcock and you need to get that addressed asap.

Drain your crankcase oil fully. Pull the sparkplug out. Turn the engine over with the plug hole 100% inverted and crank the motor quite a bit. You want NO liquid in the head. Once you are sure that it is clear...flip it back over and fill the crank to spec with cheap oil (it isnt staying in long).

New plug, gas...and get it to run. Hopefully.

If it starts up...let it idle a bit (maybe 2-3 minutes) and take it for a 10 minute ride.

Bring it back and change the oil once more and refill with good oil.

Now the bad news...

There is a VERY good chance your rod is bent. Four strokes can hydrolock quite easily. If all you did was hit the starter...then you may be ok. If you got a couple muted puffs (like it was firing) something MUST give and it is usually the rod.

Hopefully you will be ok...if all this sounds like too much, find a buddy that likes to wrench...the whole process should take no more and an hour.

 

Well if you say your carb was leaking out the overflow it doesn't suprise me your crankcase is full of gas too.

Make sure your needle and seat are ok too. Change your oil a couple times and keep an eye on it . The gas was probably there from when the carb was flooding etc. Hopefully it wasn't worked too hard with the gas/oil mix in the crank case.

I have a story about gas in the oil.............

My old honda 250 quad would fill the crank case up with gas. First time I noticed it was like what Happend to you it puked it out the crank case breather tube on the ground(freaked me out too). I was a little concerned and changed the oil right away, checked the carb etc. Originally I checked the carb over several times and what the problem ended up being in my case was how the quad was used on the farm. My father used it daily for chores. Problem was it typically had the choke on too long (cold weather) and the quad never got hot! When I took it trail riding it never was a problem because it was worked and got good and hot.

After a few monthts gas would start building up in the oil. I'd change it for him every spring (for like 15 years) and I bet there would be a 1/2 a quart of gas in there or more sometimes. The quad is still running to this day and the engine though a little tired bieng 20 years old still runs fine.

He bought a brand new honda 2 years ago and sure enough it does the same damn thing!!! Gas builds up in the crank case over winter because he doesn't get it hot enough driving it around the farm yard.

 

The problem is specific to the 150cc Chinese ATV's that use the vacuum operated petcock.
What happens is the diaphram in the petcock ruptures and leaks thru the vacuum line
directly into the intake manifold and completely fills the crankcase and cylinder with gas.
The vacuum petcock does not have a shutoff valve. There should be 2 lines running to
it. One is the gas line to carb, the other is the vacuum line to the intake manifold.
To test......the engine should not be running....pull off the top line at the petcock. This
is the gas line. If ANY gas comes out, the petcock is bad. Also pull off the bottom
vacuum line at the petcock. Any gas leaks out, even a drop, the petcock is bad.

 

Big Ric's reply makes sence.
I'd plug the vent line and install a on/off in the fuel line. $5 fix. [img]i/expressions/face-icon-small-smile.gif[/img]