Merry Christmas and happy holidays everybody.
We returned home from my wife's folks' in VA tonight. As soon as we opened the front door, strong gas smell was filled in the house. I run to the garage and found a gas puddle under wife's Ninja 250. I drained all gas from the tank. I checked and resealed the petcock and tighten all hoses. Leave it several mins, but I didn't recognize gas leak from the petcock. I started engine and didn't hold on idle, and while I tried to hold rpm, something was leaking from crankcase. It was smell like gas, but little heavier than gas. I checked engine oil level and it was way too much. I drained engine oil as well, gush! I noticed that gas was in engine oil. I can hardly think of gas over flowed into the engine rather than over flowed from carb. When I found gas puddle, it was obviously leaking from fuel house on the petcock, and the bike has slow leaking for a couple week. Does someone know what cause gas goes into crankcase? The bike has a couple houses from carb plugged with bolts since I got it from the previous owner. Could someone send me a diagram for fuel hose and vacuum hoses?

Thanks,
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I would normally suggest hitting it with a hammer, but I don't think even that will work (blasphemy) on your problem. What you need is an extra large can of Gremlin-B-Gone. But seriously, I can't think of why gas would flow into the crank case. I'll look into it for you.

 

freaking weird, i doubt its the carbs or rings or anything, it has to be some vacuum line or breather that isn't hooked up correctly

 

fuel flowing into the crankcase when not running is typical of a needle valve in the carb not closing. before i replaced my gas tank a small spec of rust did that to me. untill you find out for sure what caused it you'll need to shut off the petcock anytime the engine isn't running.

 

Did the bike run before vacation?
I think hoses may be problem, but think only ohter path is tank to petcok to carb to head to piston to crankcase. Had it happen on older honda and only path I had was tank to carb to case.
What is normal position of petcok (off, on, reserve)?
Please let us know what you find.

 

sounds like a rough time

 

I have seem this happen before and is fairly common.

 

Guys,
Thanks for your comments, encouragement, and some idea. I removed carbs and cleaned them. Also, I removed petcock and clean as well. The petcock installed on Ninja 250 is vacuum activated valve on it, so while engine is not in operation, it should be shut the fuel flow. Now fuel stops while engine in not running, but engine does not rev more than 4000rpm. Probably I need to check float level again. It sounds like engine starve for gas. The bike has barely 10K miles and me and my wife had been riding almost everyday before vacation. I think korburn is right, small particle stack on float valve and gas kept running into carb to cylinder and to crank case. I found out that Ninja 250's carbs don't have any overflow drain. In the case fuel overflows, simply run into cylinder. Shut off petcock after riding seems to be the best option to prevent the problem.