gas in air box

ok I know beyond the shadow of doubt my carbs are clean, synced and a decent tune (verified by plugs and colortune just beyond blue pugs look great tad rich)
valves in spec less than a thousand miles since reshim
compression good all within 11 psi of each other, wet test not much different.
Bike has been running great except I broke the speedo :wink:
Al of the sudden today I fill up and 10 miles later I got a wierd issue made me think a pug fouled or a coil was breaking up. I pull off the road and feel the headers #3 didnt feel as hot as the rest so I pull the plug Little black but I was running slow before pulling off, fine other than that, not wet fouled looking. fired it back up, run like crap--- oh look dummy shut it off and put #3 & #4 plug caps back on (yes I did that)
Fired it back up fine ran like normal- meaning sweet, I ride on to where Im going, about 5 miles or so. Park it and fuel is coming out the air box vent?? WTF? Faint smell of gas in case not bad almost questionable if it was really there- I drained it anyway. what the Hlel happened?
hasnt ever done that before pulled the air fiter out no fuel on it fuel never came out over the litte lip where the filter sets up to did feel fuel on the inside of the airbox boots?
what happened to my bike. new oil... etc. way home passed everything on I-10 ran like a champ with no problem. I dont know whats up??

 

What do you keep your petcock set to? Float levels correct?

More than likely a float issue. Either the float needles/seat need replaced (if they're as clean as you say they are), or the float level is too high. Petcock could be a contributor too.

 

Running it without two Plugs firing.
Gas was introduced to the Crankcase.
If enough got-in to reach the Vent Baffle, ... next stop is Airbox.
Depends how long you rode with two holes not hitting.

So, ...

Remove the Oil Filler Plug.
Sniff to see if it smells like gas.

I guess if you have Gas in the Airbox; you have to go through the list and eliminate causes.
Leaking Petcock
Leaking Floats
Float Heights
Blowby.

 

it ran for say 30 seconds if that with out 3 & 4 hitting, if that.
just wierd its ran perfect till that and perfect on the way home.
can I hear more about blow by?
foat levels verified wet with tube- sitting pure level, gas came to the screw heads on the bowls.
I dont know how I coud have got the carbs any cleaner and it has gone 800+ miles running like a dream. I first thought the coil was breaking up, I was running about 7k before that.

 

Did you inspect/replace the float needles, seats, and o-rings when you cleaned them?

30 seconds shouldnt have pulled enough fuel to overfill the crankcase like that.

 

Hmm. I did reuse the copper seat washers. polished up nice but reused them. Ok those get changed I still have some new ones in my other rack
blow by though?

 

If one of those three were leaking, the o-ring or the actual needle valve would probably be the culprit. As long as you didnt polish the hell out of the seat it should be fine.

Someone else would have to tell you about the whole blowby thing. Carbs should be the first place to look though.

 

Ill just drive the 4 wheel thing tomorrow and pull the carbs again tomorrow and change needle- seat- washer and all. I guess they can leak sometimes but not all the time? worth a shot just dont see why they did it that once only.
Any body got anything on blow by? Rick? You out there Fitz?

 

I wouldnt go on my word alone. There's plenty of wizards lurking here.

What i do know is that shit goes wrong for no reason, be it intermittent or permanent.

Shit happens, lol.

I had a problem with my petcock leaking, and my float valves werent seating right. Pissed gas everywhere once, and would lock up my engine after sitting in the heat, wouldnt even turn over because of the compressed liquid.

Float needles were old and bloated, all four are getting replaced and my petcock will be rebuilt.

Are you sure its not happening right now? Go check if theres a puddle of gas laying under your bike, or give the crankcase another smell.

If it happened once, it will probably happen again.

 

yeah I was out there with it for a while in the garage I was working on that dnam V-twin from hlel for a friend. when It did it it wasnt much, not like enough to actually puddle maybe a tablespoon full came out.
I dont know if its a clue but when I pulled the air filter right after I could hear like a sucking noise in the box. wierd

 

One clue from that is it wasnt a one time thing.

As far as the sucking noise, its probably a clue that its still leaking. If youre planning on looking at it later on I'de find a way to shut off that fuel so you dont have to change your oil again, if it hasnt already found its way in the crankcase.

 

its got a briggs and stratton shut off on it so its good for now. so that bsuckking was probably the sound of the carbs leaking? Ill kill that gremlin tomorrow.

 

Blow-by is referring to the fuel & combustion gases escaping past the rings and through the ring gap during the compression and combustion strokes. It always happens to a small degree, that's why you have a hose running from your crankcase to the breather box. Normally it's atomized gas and oil mist that can't accumulate and gets reintroduced w/fresh air and burned up. If enough blow-by is happening you could end up with fuel coming through to cause your problem.

I'm betting your float is a more likely culprit. If it's intermittent you might have a sticky float that just flooded it - then became unstuck and seemed fine. If so you're going in there to see why. Did you see fuel floating in the oil when you drained it?

 

foam like bubbles the same color as what came out yes but not alot, not like enough to cover the pan I used to drain it but a patch. i saved the oil for inspection so ill check it today. sticky float would fit I guess. I know the levels are good but if its sticking then that would make sense. why would it stick though? Ill be in it later today.

 

Gas mixes with oil; you're not gonna SEE it as much as smell it. If it smells like gas don't put it back in the motor.

As above, "blowby" is not why you have gasoline in your airbox. "Blowby" might give you excessive levels of oil vapor in the airbox; not gasoline.

Gasoline in the airbox means a carb is "dumping" fuel for whatever reason AND it has an unlimited supply of fuel to dump. The inline shutoff strangles off the unlimited supply of fuel; but that carb is going to have the same issue when the bike is running. Either you have a sticky float, or as mentioned above, fuel is leaking PAST a float valve; a good possibility if you didn't replace the seat sealing washers.

 

I've always been a little puzzled by this problem. I can go MONTHS of riding without an issue, and then one day a float valve will stick open and gas will pour out of a carb. My open-up-the-carb inspections have never revealed any "snags" or likely causes.

Unfortunately, when it happens, the best course of action is what's been proposed: check the oil for fuel, change if needed, and troubleshoot the carbs for a reason the float valve is hanging up (if any).

 

you guys are great.
Thanks fitz for clearing up the bloe by deal, theres no oil and this never happened before Ive got 4 fresh quarts of 4T 20/50 and a filter to go in. Im just gonna change needles, seats and o ring/washer. and re check float levels as Im sure once changed the levels may need setting again. I got all 4 bowl screws new so itll be easy. Ill re color tune and check sync probably compression test again for giggles finally follow up on chops
well at least I know she runs super great now cause till this happened It's rode like a new bike.
Probaby one of the fastest and smoothest of its class Ive ever been on really
Ive had guys ask me if it was a 900 and that aint no joke.
Too bad the speedo coudnt keep up. poor speedo it tried.
Ill report back after I slay the gremlin

 

carb #3 the wire clip came off the needle. anybody ese ever have this happen?
oh well new needles goin in

 

While you've got the carbs apart, pay close attention to how the floats move when they "float."

With the rack mounted in your fixture perfectly level and all the bowls off, gently lift each float and watch how it moves in relation to the rest of the parts. Make sure they all "float" nice and smooth, and none of them are "angling off" to one side, or binding against their tangs. Also check the "down" stop tabs, to be sure they all hang at the same level when open.

I'd pay particular attention to the one that lost its wire clip.

 

before I drop these in anybody got anything bad to say about J$L kits?
they have viton tip spring loaded needles but the clips look pretty cheesy

 

Just an update, Replaced needle, seat, and seal. 3 days and all is well, cant say for mileage as speedo died earlier this month.
Gonna totally rebuild the spare rack to prestine condition for later and I found some non ethonal gas!
Never did see a problem in the carbs, maybe it just wasnt on good to start with? got the oil to "little bubble" level and Ill monitor it CLOSELY.
guess now Ill redo the chops as I made slight adjustments for color tune and wet set levels for the new needles.
These Hitachi carbs are strange little creatures