Airbox flooding

[WMarshy]

I went to start my bike after sitting about 10 days and it started and ran for about 30-40 seconds then stalled and started puking fuel out the carb box... Today I took the bottom of the air box off and started it up and after about 30 seconds carb number 1 and 4 started to overflow and dump fuel out the back. Took it all apart and carbs are now out of the bike. Discovered the left petcock was leaking slowly and have fuel in the crank case. If the petcock is leaking is it just a matter of cleaning it and re-assembling it? I plan to drop the bowls off the carbs and hose them out with cleaner because the fuel puking out of them was quite oily and dirty. How would the fuel get so dirty? I understand the crank case vent might contribute to the air box being dirty and everything but it seem like there is excessive oily gas in them...
To do list: Check floats to see if any have hole in them, take float needle out and clean seats... Any other suggestions while Im there? It really burns my a$$ because they were just cleaned about 200 miles ago. Suggestions are encouraged. Thanks guys.

[WMarshy]

I thought I should ask/point out that the carbs seemed to only leak gas after it was running. Maybe I dont know enough about theses bikes yet but to me that points more to a carb issue than petcock. I know that would contribute some but...IDK

[tw1980]

If gas overflowing out of your carbs the floats are sticking.If you have an octopus still then fuel only flows to carbs when a vacuum is supplied to the unit.Thats why it only floods when the bike is running.Check the needles valves and seats and make sure the floats aren't hanging up.Terry

[Bigfoot]

Definitely stuck floats. If you are getting gas in the oil while the bike is sitting then the octy isn't doing its job properly (if you still have one).
It is worth a try to just clean out the petcocks. On my MNS I just cleaned mine, the diaphrams were fine, just crudded up. I believe that you can get rebuild kits for them still.

Edit** Now that I think about it, did the 79 have and Octy or did that come about in 80?

[bikerphil]

Only Specials had the octy. He has a 79 Standard with the vac operated petcocks. Try cleaning the petcocks first before rebuilding/replacing them. Some gunk may be stuck in the diaphram's O ring seat. Do a bench test on the carbs before putting the bowls back on to check for leaky needle/seat.

[Ken Talbot]

Keep in mind that if you ever have gas leaking out of the airbox on a Standard, you have two problems. You have one or more defective petcocks, and you have one or more stuck floats. Not just either/or, you have both problems and they both need to be fixed. Same goes for a Special, but substitute octopus for petcock.

[TopCatGr58]

Hey Marshy,

Did you install INLINE fuel filters?? IF not, that would be the other big thing to do, to help keep the tiny particles from getting into the carbs from the tank, and wedging between the float needle and seat causing it to leak....IF you find that your floats are not sinking. Also look very closely at the float needles. IF you see a fine line around the tip, then they could have worn a groove into them, and that can also contribute to them not sealing as well.

IF the float needles are working properly, a leaky petcock will NOT cause a problem, but when the float needles fail, and the petcocks are leaking, then you get what you got, fuel in the oil!

Aside from cleaning the petcock parts, you can try rebending the wavy washer a little more to increase it's tension to help seal things. Also suggested to polish the surface of the metal valve so that it is smoother and will seal with the rubber valve better.
T.C.

[WMarshy]

Update

Well, I went to autozone this morning and bought oil for an oil change and picked up some inline fuel filters + carb cleaner. Phil is right, no octy on my bike just good’ol vac petcocks here. I will try a cleaning tonight to see if that does the trick for them. Is it ok to clean petcock/diaphragms with carb cleaner? The tank is conveniently full of gas right now, i guess the easiest way to empty it would be siphon..?
During my morning commute I put together what I think is the most likely cause of all this. About two weeks ago my bike was tipped over in the parking lot at work. Read full story here: http://www.xs11.com/forum/showthread.php?t=23244
The air box was flooded and I believe some of the crud from that mishap made its way into the carbs. I think if the air box was cleaner then this may not have happened! (Note to self, move crank vent somewhere else…Ideas?)
So I will break down the carbs and hose them out, I doubt the floats are hung up Im convinced the needle valves are all shizited up from that gunk it sucked up. I will probably invest in a K&N air filter also…

Question about the bench test, can you elaborate on the device required to do this and what it indicates about the carbs? Does it tell you anything other than if the needle valves are leaky? Is it a professional tool or is there some contraption I can make to do it my self? If there is a detailed thread about bench testing please pass it on. ITMT I will search for more info. I wont be able to work on my clutch until this issue is resolved. I hope the comming weekend isn’t a wash! Thanks guys, will update later.

[trbig]

Another thing that may have happened, was after sitting for so long, the gas in the bowls evaporated and let the floats drop to their max level. Sometimes this is too far, and the float pin comes almost completely out of it's hole. When the float tries to raise back up, the pin gets cocked in there sideways and lets the fuel flow. A lot of times, a simple rapping on the side with a screwdriver will fix it if that's the case.

BUT.. this doesn't fix your leaky petcock.

Tod

[WMarshy]

Another thing that may have happened, was after sitting for so long, the gas in the bowls evaporated and let the floats drop to their max level. Sometimes this is too far, and the float pin comes almost completely out of it's hole. When the float tries to raise back up, the pin gets cocked in there sideways and lets the fuel flow. A lot of times, a simple rapping on the side with a screwdriver will fix it if that's the case.

BUT.. this doesn't fix your leaky petcock.

Tod

Good point, maybe from being over on its side though..? screwdriver handle didnt do it so off they came.

[bikerphil]

Bench test thread.....

http://www.xs11.com/forum/showthread...ght=bench+test

[TopCatGr58]

And Marshy,

Don't worry too much about the stuff in the airbox! If any crud was there would have just gotten sucked right thru the carb throat and into the engine, not down into the float bowl or fuel lines, no way really for it to get there. So...really no need to relocate the crankcase vent hose. A clean air filter always helps.

More likely, the tip over stirred gunk/sediment in the gastank, and then after sitting it back up, is got washed past the petcock filter towers, or even the filter towers could have gotten knocked loose/off?

Aside from siphoning, you could also just connect a fuel hose to the petcock and drain it into a large 5 gallon gas can. It'll take a few minutes but you can be doing other stuff...like removing the carbs while it's draining!

Don't know if you were planning on taking the petcocks OFF the tank vs. trying to work on them while still installed? IF you take them off, there is a rubber O-ring that seals them to the tank, it will have most likely gotten flattened, you can find an equivalent one at local hardware store, nitrile or neoprene, just not natural rubber! Also felt washers are used under the heads of the screw/bolts. But when you pull the petcocks out, you can verify that the filter towers are there, and even clean them, perhaps even wash out the gastank a bit since it'll be easier to get larger particles out thru the petcock holes while they aren't there! Just don't use a CHAIN to scrub the insides...use loose bolts or ball bearings or such, the chain can get wrapped around the gascap drain tube and fuel sender float....just ask Fredintoon! :P
T.C.

[WMarshy]

Well, last night I got around to cleaning the carbs. There was definitely a lot of junk behind the screens of the main jets and in the fuel supply circuit for them. I have inline fuel filters now and will be putting them on after I tinker with the petcock. It sounds like its worth pulling the unit out of the tank and seeing if the screen/tower is still connected then clean it. I will probably just rinse my tank because it has been sealed, no real need to scrub it...

On another note, I think I may have two leaky carb slide diaphragms. I held my finger over the oblong oval shaped port that faces the filter and released the slides that were raised about an inch and could see #1,2 slowly sink closed. I was thinking about making a short clip with my camera and posting it to show the difference between the good ones and the suspected bad ones. Correct me if I’m wrong, is that the correct way to test them, I thought that is what I read in a post..? What is the consequence of having a leaky diaphragm, lean combustion in those cylinders…maybe the incorrect ignition advance due to the lack of vacuum? I found the replacement thread for those… doesn’t sound like a walk in the park, and man are they expensive! Who’s the cheapest source you know of? PNM lists them for $65 each. Thanks guys!

[tw1980]

I replaced my slide diaphragms last winter.It wasn't that hard.I got 4 on ebay for around $90 I think.But one of them tore a hole last weak.I don't know if I damaged when I installed it or if they're an inferior product.I ordered a new one from MikesXS $66 and it comes with the slide.Terry

[WMarshy]

I replaced my slide diaphragms last winter.It wasn't that hard.I got 4 on ebay for around $90 I think.But one of them tore a hole last weak.I don't know if I damaged when I installed it or if they're an inferior product.I ordered a new one from MikesXS $66 and it comes with the slide.Terry

Did the ones from ebay have the slides or did you do the cut and glue trick? Man they really stuck it to us on these parts, why are they so expensive?