Gas in oil...a lot

Hey guys. I went to start my bike Friday and she started but wouldn't keep running. While she was running, shifting was almost impossible. I was trying to run some sta-bil through the system for the winter. After she wouldn't run I just gave up and left it alone. This morning my wife said the garage smelled of gas really bad. I went out to find a huge puddle of gas and oil under the bike. It was dripping from the timing cover. I pulled the cover off and it was just dripping from the bottom inside the timing cover. I looked at the oil level through the oil check window and it looked like it was way over filled. I took off the filler cap and smelled a strong gas odor. I drained the crankcase and a huge amount of oil and gas poured out.

So here's the deal. I rebuilt these carbs and did a valve adjustment back in sept. I changed all the seals so I know it's not the needle valve seat seals. The floats are fine as well. I checked the air box and it's dry as a bone. The only thing I can think of is the petcock. If it's leaking, would this cause gas to leak in to the oil?

 

Unless you had the petcock set to "PRI" it is leaking. But it's only a safety, designed to prevent what happened if the float needles don't close. You have a carb problem too.

 

Nope. Not on PRI and not on RES. It's in the ON position. I'm going to pull the fuel line off and see if it's leaking. When you say a carb problem....what would you think it is? They ran fine in sept after I rebuilt them. Needle valves were seating properly and the needle valve seats were not leaking. Checked all of it before I put the float bowl covers back on. All brand new seals.

 

Do not try to run the bike. Your carbs flooded the engine. At least one of your float needles is sticking. You will have to get an oil change, oil filter AND, check your float needles, either one was stuck or the float levels were way way off.

If you had your petcock on ON and it is a vacuum operated you have a faulty onethat will need attention aS well.

 

Yeah I was just reading up on it in the forum. I could swear I adjusted the floats properly. Dry then wet. I'm going to get a rebuild kit for the petcock and I guess I'll have to revisit the floats again.

In the meantime I'm going to pull the fuel line off the tank so no more gas floods in to the carbs.

 

The most likely culprit is a bit of rust lodging itself between the float needle and the seat. Pull the float bowls (will need to remove the carbs unless you replaced the bowl screws with allen-head bolts) and check for any bits of rust. Also make sure that the float needle clips are oriented so the needles move freely (flipped the wrong way and the needles can bind in their bores). After that install a fuel filter between the petcock and the carb.

 

Thanks k-moe.

I can get the bowls off no problem. I just have to remove the seat and gas tank. Seeing that you mentioned the orientation of the needle valve. Take a look at the pic I posted. My needle looks just like that except the clip is silver not black. (exactly like the second pic) Now which way should I put the tang through? Should put the tang through in the direction as shown by the arrow #1 or put the tang through in the direction like #2 shows?

 

You want the clip to be centered on the lower part of the curve in the float tang, or slightly toward the outer end of the tang (away from the pin), so the needle is free to move without binding. You can check for binding by hand with the bowls off, but use a light touch; enough force and the needles will move fine, but still bind when the only thing making them move is buoyancy and gravity.

 

So basically doesn't matter which way the needle goes on. It's the position on the tang that matters. If that's the case, wouldn't the needle sit on the tang where it sits in the seat? Wouldn't that determine where the needle sits on the tang?

Something else I just thought of. Suppose the floats are fine. Adjusted properly and the needle valves were closed. But...the petcock was faulty and kept dumping fuel in the bowls. Wouldn't a certian amount of pressure build up in the bowls to cause the fuel to blow past the needles? Or....would it just go out the 2 overflow tubes on the carb rack?

 

No, the maximum amount of pressure at the petcock is the hydrostatic pressure, which is:
= density(gasoline) x gravity x height(in fuel tank)
and is caused by the potential energy of the gas in the tank (it's slightly higher when the tank is full). The hydrostatic pressure is no-where near what it takes to "blow past the needle." (rough back of the envelope calculation give me about 0.3 psi for gas 1 ft above carbs. For reference, my Turbo seca has a fuel pump and regulator to maintain a pressure differential between the "atmosphere" in the carb (boost from compressor) and fuel pressure, of 2 psi. You'd have to raise the tank several meters to get even that fuel pressure.

Gas can only get to the engine one of two ways from the petcock, overflowing the bowls due to a failing needle valve, or a failure in the diaphragm in the petcock for the vacuum line. Have you checked if fuel pours out of that line (there should be no fuel in that line under any circumstances).

 

Holy crap Bot. You should have been a physics teacher or Bill Nye the science guy or somethin. Thank you for that detailed explanation though.

I can tell you for a fact the diaphragm in the petcock is bad. As soon as I took the line off, gas kept dripping out and it wasn't on PRI. I've already ordered a rebuild kit for it. I just checked the vacuum line and it's dry so I'll be pulling off the float bowl covers and checking the needle valves. Perhaps they're binding or something is lodged in there as k-moe mentioned. It's hard to imagine the floats would be so out of wack seeing that I just adjusted them within the last 2 months. Dry and wet.

 

I watched this lecture a couple of months ago, trying to brush up on some physics since it's been about a decade (I didn't have this professor, but his video lectures are legendary).

 

My physics professor in college made us build a roller coaster to certian specifications with Disney's roller coaster tycoon. (Obvisiouly a beginners class) A certian amount of inclines, declines, loops, flat spots, etc... We had to show examples of Potential vs Kenetic energy and where on the roller coaster they occured. The roller coaster had to be built in a way so that once that first up hill climb (potential energy) was done, kinetic took over and the ride had to comple in a designated amount of time. It was fun but a bit of a PITA. Quite interesting though. I give credit to the engineers that design those things. I'm sure a heck of a lot more work has to go into building those things in real life than energy considerations. Don't wanna kill anyone with too much G force. Ha.

 

[It is the petcock, vacuum operated and it is letting the tank drain into the cabs and then into the engine. Hopefully it hasn't washed out and ruined your bearings.

 

The petcock alone will not cause fuel to get into the crankcase, unless the vacuum diaphragm has failed (allowing fuel to get into the vacuum line). Both issues have already been discussed earlier in the thread.