Bike filled crankcase with gasoline.... help?

[SV_Hadder]

The bike had been sitting for about a week and a half while I was away on vacation... When I got home, I changed the spark plugs and noticed the left one was soaking wet, I wasn't quite sure what to think? I also adjusted the carb needle and found the rubber diaphraghm covered in gasoline and it was larger than it should have been (due to the gasoline, I'm sure). I put in the new plugs and went to start it, and this is what ensued...

I started the bike, and it was running kind of rough, and then a few seconds afterwards it started pissing gas out of the bottom of the airbox, and so that made me decide to disconnect the crankcase vent from the airbox.... That crankcase vent shot a stream of gas/oil about 10 feet.

At first I thought maybe it was because I left the gas on, but then I remembered that the only way gas will flow from the petcock is if it has vacuum from the engine. Since the bike had been sitting for a week, there was no way it could have had any vacuum pressure.

So I changed the oil and filter, and everything was fine for a week. I rode it to college last night, it ran perfect. I parked it for 2 hours with the petcock OFF. I go to start it and it is running really rough, the right cylinder was intermittently running. I rode it about a mile across campus to grab a bite to eat, and the running issue never really cleared up. I parked the bike to get dinner, turned the petcock OFF, came back an hour later, and the bike smelled of gas. I tried to start it, with no success, so then my battery died, and I waited 45 minutes for campus police to give me a jump. I got the bike started as the cop pulled up, I held the throttle wide open to clear out the unburned fuel, and it finally started.

Once I got it running, it ran fine, and then i turned the petcock ON, and it started running crappy again? Sounds like a leaky float maybe? I just rebuilt the carbs a few weeks ago and found everything to be in pretty good shape. Sorry for the lengthy post!

[bob706]

Have you tested the petcock?

[mrlmd]

Your carb floats should still shut the gas off if they're not stuck or there's dirt in there.
Something must have been done when you took the carbs apart.
You could try some Seafoam or Berryman's first but you may have to take them apart again.
And just for laughs, see if gas drips from the petcock in the on position with the engine off.
Also did you check your oil and the level again? You may have to drain and change that again too if the oil is filled with gas.

[SV_Hadder]

I disconnected the fuel feed line from the petcock and turned it ON while the engine was off, and I got nothing, so I'm pretty sure the petcock is fine.

mrlmd, I already changed the oil right after it happened and I am planning on changing the oil again soon... It sucks because I had just put in synthetic about 100 miles before the bike decided to add gas to its crankcase. So that was about 15 bucks wasted, and now i have to change the oil 2 more times to clear it out...

[Jinx250]

There are 2 problems here. Leaky petcock and leaky float. If your float was fine, even a leaky petcock should not fill your crank. If your petcock wasn't leaking, you should not have this problem. I'd recommend cleaning the carbs again, being as meticulous as possible, and also removing the petcock, disassembling it and cleaning it up (do not use carb cleaner).

[darrell85]

I completely agree with jinx250. I had the same problem after my bike had set for a while. however I didnt have the time to rebuild the petcock and clean the carbs right away, so I just put in some fresh oil, dumped some sea foam in the tank, and after a ride when I got about a block from my house I would turn off the petcock. this gives it just enough time to use up most of the fuel in the lines and carb so nothing leaks into the crank while it sits. also, the seafoam apparently removed whatever dirt that was in the carb. the petcock is vaccum operated and has a diaphram in it. this is probably needing replaced. you can buy a petcock rebuild kit cheap on about any site that sells 250 parts.

[SV_Hadder]

Okay, so of the two possibilites, petcock or float, I am heavily leaning towards the leaky petcock. The bike runs the same as it has since I have owned it, so I know its not running overly rich, which would indicate a leaky float.

I read on another ninja forum that you can dissassemble the petcock, remove a diaphraghm spring and cap off the vacuum ports; thus creating a true ON/OFF petcock regardless of vacuum. Does anyone know anything about this quick fix?

[FrugalNinja250]

If the engine is off the petcock can't flow. If you're getting problems with running while the petcock is open and can make it run better with the petcock turned off I'm inclined to think you have a perforated vacuum diaphragm in the petcock that's allowing fuel to flow into the carb by way of the vacuum line. The carbs don't have a common vacuum rail so only one carb would be affected, the left side. This fuel will bypass the float and bowl, instead going directly into the carb throat.

[SV_Hadder]

To add even more confusion to this problem... just yesterday I rode the bike about 20 miles in 30 degree weather with snow falling and it ran perfect. It started fine, ran fine; I even shut it off and restarted it about 4 times with no trouble whatsoever. Everytime I DID go to park it I shut off the petcock. Who knows? Probably just keep riding it and if it does anything weird again, I will post back.

On another note, why does my airbox drip gasoline or oil (not really sure which)? I thought it was from a faulty crankcase vent hose, but I'm almost positive that its leaking from the bottom of the airbox. If the airbox leaks stuff OUT, that surely means stuff can get IN, right?

[mrlmd]

It's not your petcock, it's from sticky carb floats, dirty needle valves - the carbs are overflowing. Use the Seafoam or Berrymans and see if that clears it up or take them apart again and clean them and undo what you did last time.

[darrell85]

if your oil level is too high, even just a little. the excess oil will get pushed up into the air box through the crank case breather tube that goes from the front of the air box down to the crank case. after the oil is in the airbox it will run out of a small drain hole on the left side of the air box and you will have a puddle of oil on the ground near the kickstand. these little 250's are very pickey about how much oil you put in. dont worry, nothing is wrong with your air box that hole is therre from the factory and needs to be there to get rid of excess oil, or an oil-gas mixture, if problems like this occur. I definately reccomend draining your oil to get that gas out of there. gas is'nt a good lubricant.

[mrlmd]

If you've got gas in the oil, you have to change the oil AND the filter, and maybe do it twice or more to flush all the gas out. Besides being a piss-poor lubricant, there is also the risk of an explosion.
There is nothing wrong with your crankase vent hose - it's doing exactly what it's supposed to.
You ask a question and I don't know why you refuse to listen to the answers given. Your problem is with your carbs. They are overflowing. You are leaking gas into the cylinders, down past the rings into the crankase, and out the vent . Clean the carbs, the floats are sticking, the needles are dirty and not shutting off the flow of gas. It's pretty simple but you keep looking for some other explanation, grasping for a solution.

Or bring it into the shop and let them fix it for you.

[SV_Hadder]

Whenever I rebuilt the carbs I didn't even disassemble the float needle assembly because the bike had been running perfect, and the rest of the carb didn't look bad at all. I figured there was no reason to pull the float needles and clean them. Looks like I get to do it all over again and hopefully it will fix my problem.

And mrlmd, I was not ignoring the posted fixes, I was simply checking for other possible problem; no need to get all antsy.

[mrlmd]

I guess I did come off a little strong, I was trying to get you back on track as to where the problem lies, instead of you going all over the place. Sorry about that. But I think as do others here, that the problem is in your carbs. And after you get it fixed, the oil and filter have to be changed again, maybe twice, so it's clean.
Keep us updated as you go.

[SV_Hadder]

No harm done I just rode the thing about 20 miles again, and its surely the damn float needle, or float itself. If I ride it with the petcock ON, the right cylinder runs terrible if at all, and the carbs piss fuel out of the overflow tube. However, if while im riding it and I turn the gas off, it runs fine and does not leak, but a second or two after I turn the petcock back on, it returns to rough running and streaming out the overflow.

I emptied the float bowls multiple times using the float bowl drain screws, and I also rode with the petcock off and burnt all the fuel out of the float bowls, and I even tapped on the carb floats hoping to dislodge my stuck float.... all to no avail whatsoever.

Guess I'll be tearing them apart this weekend. Thanks for the advice guys!

[mrlmd]

That right cylinder's getting flooded with too much gas.
Have you checked your oil level again to see how high it is?
You tried Seafoam or Berryman's in the gas to see if it frees up the float?
You probably should just bite the bullet and get it over with and take it apart (again) and see what's the matter with it.

[SV_Hadder]

I think I'm just gonna go ahead and rebuild them, I need to drill out the pilot blanks anyway. I'll post back whenever I find what the problem was.

[SV_Hadder]

Took the carbs off, and found that the right float bowl screws were pretty loose. Whenever I rebuilt the carbs a few weeks ago I put in allen head bolts rather than reusing the OEM screws that are made from swiss cheese. I guess I didn't tighten them enough or they came loose progressively, but I tightened them up, as well as put loctite on them. Rode it yesterday for 30 miles, no problems. Rode it 60 miles back to college today in the pouring rain, no problems.

Loose float bowl screws mean the fuel was leaking out and constantly asking for more fuel. Tightening the bolts could have been done without removing the carbs, but I wasn't sure what the problem was.

Thanks for the advice!

[mrlmd]

Well I guess we're not as stupid as we come off on here. You're welcome.
Glad you got it fixed and running, and don't forget to CHANGE THE OIL AND FILTER AGAIN! And put some Berryman's B12 Chemtool ($3 a can) or Seafoam ($10 a can) 1oz/gal of gas into the fuel tank every 3 or 4 fill-ups and you'll never have to screw with the carbs again.

[SV_Hadder]

Originally Posted by mrlmd

Well I guess we're not as stupid as we come off on here. You're welcome.

Arrogant much?

There was no stuck float; there was no dirty float needle. Perhaps now you can see why I was "Grasping for another solution?"

[mrlmd]

There's no arrogance here. I and others told you what the problem was from the beginning, and you wanted to play with the petcock. No matter what the exact reason was, we said the problem was in your carbs, a problem with the floats, and they were causing leaking of gas into the cylinder and out the vent hose. You yourself caused the problem. You were the last one in there, and that's usually where the problem starts. Why did you have to rebuild the carbs in the first place, and what exactly does "rebuilding" mean?

[SV_Hadder]

I had to put in larger mains for my two brother's exhaust and I figured I would do a routine cleaning to make sure everything looked good. I guess I used the term "rebuild" interchangeably with "cleaned".

[mrlmd]

Just glad you're up and running again.
Seriously, change the oil and filter again - oil diluted with gas is a lousy lubricant and also, go the Berryman's or Seafoam route and you won't ever be messing with your carbs again.

[SV_Hadder]

Yup I'm glad it's up and running, too!

I changed the oil and filter twice already with non-syn Rotella-T. Pretty sure its all cleaned out of there by now. Next oil change I'll be going to synthetic Rotella-T