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Discussion Starter · #1 ·
300 king quad.

Oil just dumped out while driving, no smoke, runs fine, oil everywhere!
I De grease the engine so as to see where oil is coming from. Put new oil in...

Bike is running fine until so much gas gets into oil that it starts leaking oil, no idea where from.
Changed the oil, drove it 100 yards and I can see through sight glass oil chamber is full again! WTF??
Why is gas getting into oil compartment? I can't believe it runs so well with this going on?
Anyone have any ideas?
 

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The carb needle and seat, float, dloat height , or vaccum petcock (if your model has one ) could i beleive be bad.
 

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Also welcome to the forum!
 

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Discussion Starter · #4 ·
Ty man! Hard to believe it's the carb but I have seen funner things than that in life. No oil in air filter too. Bike runs so good it's scary.
 

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Discussion Starter · #5 ·
Mr auto I think you hit the nail right on the head!
I found a post on this form from around 2012 where a guy(Tim, I think) broke this part down with pic's and all. It's so weird that that much gas can get into the oil and it still runs fine. Must be very rich.
I will order a new one.
Thanks again!
 

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I'm leaning towards the fuel petcock being your problem. Especially since your crankcase fills with fuel rather quickly. To check to see if the fuel petcock is bad pull the vacuum line (Smaller Line), off at the fuel petcock. If the line is wet or fuel comes out that line or port where you removed that line then the fuel petcock is bad and should be replaced. You can however band-aid fix it by plugging the vacuum line and the port at the carb and running your atv with the fuel petcock set to the Pri position. Note that you should always return the valve on your fuel petcock back to the On position whenever your atv isn't running as this setting still acts as a fuel shut off when the engine is off.

But I highly recommend replacing it if it's that far gone. To check to see if your atv has the vacuum operated style fuel petcock. You can tell by checking the settings it has stamped on it. If it's the vacuum operated style fuel petcock it'll have On/Pri/Res stamped on it. If it's the none vacuum operated style fuel petcock it'll have On/Off/Res stamped on it. Also, the vacuum style fuel petcocks also have the extra line on it for vacuum. Where as the none vacuum operated style fuel petcocks don't.
 

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There is another possibility of those don't prove to be the solution.

First, lets think about this for a second. The only connection for fuel to even get to the crankcase is through the carburetor. If it is following the normal path, the fuel would get dumped into the combustion chamber

Typically a bad vacuum line or needle/seat would take time to seep down around the piston and then into the crank case. And, like you thought, it would run very rich.

So the other path it can take is if there is a bad seal in the valve/rocker area where the fuel goes down the cam-shaft chain into the bottom.

Now, taking my first statement back a little bit...
The only way fuel can get to the crank case and not go through the carb first would be if the gas tank vent line is putting fuel into the vent lines all the way down to the transmission/crank case.
 

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Discussion Starter · #8 ·
Thanks Aj, yeah it's the on off res, no extra vacuume hose going to the peckcock. Kind of took a little wind out of my sails seeing that it did not have the vacuum hose. But I feel that I am headed down the right road.
 

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Discussion Starter · #9 ·
Ok Bear, the bad thoughts are going through my head again. It does not look good for this atv.
About a gallon of oil and gas came out of the crank case when I emptied the oil.
The sight window on the crank case was filled to the brim.
When I put oil in it, it was not even half way up the sight glass. Drove the thing 100 yards turned the bike off and it was full. Started back up and drove it back into the garage.
 

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The fact that it is starting and runs means that it has compression. For it to fill up that quick, it has to be going through somewhere else.

If it was seeping around the piston that quick, it would be very hard starting if it started at all and have low compression.

Assuming the vent hoses are not really messed up, it leaves my first alternate.

If, it has a leak on the top end, it would be under pressure and could spray (i.e. fill it up) quick.

As this machine been worked on to the point of pulling the motor? If so, I'd recheck all of the vent lines first. Easy, piece of mind.
 

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Discussion Starter · #11 ·
I'm taking it very slow. I have not even taken any plastic off this bike. It's old but has low hours. Thanks again for all your help.
 

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The fuel pump is vacuum operated. If the diaphragm in it is no good then it will suck fuel in through that port and so long as it still has more than a half tank of fuel the machine will run just great because it's still higher than the carb.
 

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King, do you think the fule pump failing would cause fule to dump into the crank case?
I bought a basket-case '92 KQ 300 last spring and spent the summer rebuilding it. My fuel pump was full of gas, water, rust and scale. The quad would not run at all when I got it. That rebuild is the extent of my knowledge about these quads, but I'll throw out my $.02 worth. Remember it's worth exactly what you're paying for it. ;)

If your fuel pump is bad, it could be sending fuel down the vent line back to the carb. You'd still have to get that fuel from the carb into the crankcase. And the quad would not run very well at all.

One thing I have noticed is that as you shift through the gears after an oil change, the oil level will go up and down in the sight glass until you have enough oil in the crankcase. I went through a stretch where I thought I had a massive oil leak, because I'd fill it up, ride it around the yard and it would be at the low mark on the sight glass again.

I ended up putting too much oil in it. There's a screw on the motor right beside the sight glass that you can pull and the excess oil will come out. I did that and got a few drops out, so I know I'm only slightly over-full even though the sight glass shows oil right up to the top of it.

If your KQ is running well, I don't think you can have a major problem with the fuel pump or carb. If you did, it would run bad or not run at all.
 

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The fuel pump is vacuum operated. If the diaphragm in it is no good then it will suck fuel in through that port and so long as it still has more than a half tank of fuel the machine will run just great because it's still higher than the carb.
This is true, however, the fuel line and vacuum line both connect to the carb. For fuel to get down to the crankcase, it would need to go through the carb. For it to fill up that quickly, there must be another path.

Seeping around the piston would not only be slow, it would also make it run very badly and would be extremely hard to start.

Only two lines coming out of the gas tank. Vent and one to the pump/carb.

I hope the OP post what he finds. This is an interesting mystery.
 

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Nickbob,
did you get this figured out? I just bought a '98 KQ 300. Mine has set for a year. I know the Petcock valve is bad, as gas just poured out the vent line. But I want to make sure I fix this right.
 

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If gas poured out the vacuum line on the fuel petcock that could be the whole problem or part of the problem. So if gas is coming out the vacuum line on the fuel petcock, you should replace it regardless cause it's gone bad at this point.
 

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If you are open air trailering your King Quad, you need to install an inline gas shutoff valve next to the petcock valve if your existing petcock does not have an “off” position. The air flow in and around the atv at high speeds works like a vacuum on the snorkel carburetor air intake and will draw gas from the fuel tank which can find its way into the crankcase. Before trailering, shut off the gas flow and burn existing fuel out of the fuel lines.
 
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