fuel in my crankcase.... what do you think?

[indiana__andy]

Hey guys, im new to your site and hope to enjoy its contents for some time. I have a problem that im trying to deal with. First off, i have a Yamaha Maxim X, which is the xj700. Its a cruiser with a sportbike inline 4 engine in it. I have fuel mixing with my oil in the crankcase. I discovered this when it was flooding itself out, acompanied with the starter "sticking" before starting. I checked the fuel filter to start troubleshooting and saw a pudle of fuel/oil in my air box. I pulled the breather tube while running the bike and saw a milky, oily, fuel substance shooting out of it from the crank case.. I already cleaned the carbs, shot air through all the ports, and cleaned it well. I saw no signs of wear in there although i did clean out alot of debree. I bought a new filter, new plugs, bike runs good, for now, with the exception of the starter sticking, which i believe is because of the nasty oil/fuel mixture in the crankcase not providing sufficient lubrication. I think that the carbs are allowing the fuel so slip on by into the cylinders, and into the crankase while it sits... what do you all think? Should I fork out the money for a carb kit?

[indiana__andy]

well turns out I was right. I had fuel seeping into my crankcase, flooding my engine and contaminating my oil... so beware. if your bike acts like its flooding given the symtoms described before. you could have the same problem I did. Its not uncommon, all I need now is a carb kit. thanks anyways.

[mccolo]

My Kawasaki Concours would barely run just when I was all loaded up for a nine-day trip. I stripped all the bags off and barely made it to my dealer, where they found fuel in the crankcase. A change of oil and it ran fine but I wasn't about to take it on the trip. Luckily I have a second bike, an old Honda CB750 Custom.

Same thing happened again some time later but this time I finally figured out what the problem was. I had left the fuel lever in the "prime" position and that just fed fuel to the cylinders, where it seeped past the rings into the oil pan. I've never done that since and I've never had the problem since.

[Maico Shark]

Well I'm kind of "old School" but this problem can be caused by a float seal on the older bikes. If the float doesen't seal properly the fuel keeps running into the intake. I never heard of a prime position on a tank, just on, off, reserve. Just turning the fuel tank off when the bikes not running can help but sometimes float needles and main jets wear out and need replaced.

[redlinemarc]

There could be some water in your gas tank and in your carbs.

one way to check is to put a clear plastic fish tank hose on the fuel bowl drain nipple and drain the bowl into a clear glass, then hold the glass up high and look at the bottom of glass. if theres water in there you will see it.

if theres enough water in your carb bowls it can cause the fuel inlet needle to stay open and the fuel keeps running through the carb going into the head and down into the crank case.

if thats the case you will have to drain the fuel tank and let it dry out and drain all the fuel bowls out. change oil and filter.

if water sits too long in your carbs it will turn to a white scale which will clog fuel passage ways. best thing to clean it with is limeaway.

the problem might not be with the starter I'm guessing. that could be liquid fuel in the cylinder. you see the piston cant compress the fuel as a liquid in the same way it compresses air. that stops the crank from turning.

there could be a peice of dirt holding the float needle open or maybe the needles adjustment wire got bent while cleaning the carbs. did you put a float back in there upside down ?....I did that once and had to redo it.

good luck

redlinemarc.

[kz1000g]

Sounds like you have a problem with the fuel shut off. They are vacum attivated. Look to see if the vacum line came off, or is cracked.

If it is a manual shut off, start turning it off when you are not riding.

Paul Sr.
kz1000g