FloridaSilverBird Posted November 14, 2011 Share Posted November 14, 2011 Gas has been leaking out of the air vent lines leading into the carburetors so I opened the airbox and to my horror this was because gas was filled up the brim, even into the airbox on the left side (was on the side stand). Any ideas on why is this happening? It seems to be a problem with the tank/petcock because gas is slowly going through the gas tube even when the tank is off the bike. My petcock is all the way on and I have recently replaced the fuel screen and cleaned the carbs. Lastly, in my troubleshooting I turned the throttle and all the gas in the carbs drained. Did all that gas just pour into the cylinders? Will this be a problem when I start it up again? Thank you. Quote Link to comment Share on other sites More sharing options...
Chewtoy Posted November 14, 2011 Share Posted November 14, 2011 Gas has been leaking out of the air vent lines leading into the carburetors so I opened the airbox and to my horror this was because gas was filled up the brim, even into the airbox on the left side (was on the side stand). Any ideas on why is this happening? It seems to be a problem with the tank/petcock because gas is slowly going through the gas tube even when the tank is off the bike. My petcock is all the way on and I have recently replaced the fuel screen and cleaned the carbs. Lastly, in my troubleshooting I turned the throttle and all the gas in the carbs drained. Did all that gas just pour into the cylinders? Will this be a problem when I start it up again? Thank you. Carb floats stuck or mis-adjusted is my guess. I'd start there. And, yup, you have another problem now. Gas does NOT compress. Get a fire extinguisher handy, and remove the spark plugs and turn the engine over via the rear wheel. If you use the starter, you may create a spark, and with all that gas splashing around, you'll have a fire. And, you now have gas in your engine oil, so you get to change that as well. The good news is you really didn't hurt anything Quote Link to comment Share on other sites More sharing options...
blackhawkxx Posted November 14, 2011 Share Posted November 14, 2011 I don't understand why the air box filled up. If the float is stuck, the extra fuel should have went out of the carb overflow tubes onto the ground. Quote Link to comment Share on other sites More sharing options...
Zero Knievel Posted November 15, 2011 Share Posted November 15, 2011 When something like that happened to me, it was because the asshole of a mechanic sabotaged my petcock to cover the attempt of another mechanic to dump dirt in my tank and say it always was that way. Spring was missing...vacuum activated petcock. Basically the valve stayed open and the gas kept flowing. Don't know if that's your problem or not. Quote Link to comment Share on other sites More sharing options...
FloridaSilverBird Posted November 15, 2011 Author Share Posted November 15, 2011 I don't understand why the air box filled up. If the float is stuck, the extra fuel should have went out of the carb overflow tubes onto the ground. That actually sounds like it might be exactly my problem. I had to replace the fuel screen but I do not remember anything about a spring either when i took the old one out or when I put the new one in. I did not receive a spring with the fuel screen (ordered from ron ayers). I have thought that the problem was with my tank because it continues to leak gas into the carbs, clearly explaining why it is filling up. It's also leaking all over the place when i take it off the bike. So, is there supposed to be a screen inside the fuel screen for a 98 bird? Maybe it fell out while taking out the old fuel screen and it is somewhere in the tank... Quote Link to comment Share on other sites More sharing options...
blackhawkxx Posted November 15, 2011 Share Posted November 15, 2011 Does this help? http://www.ronayers.com/Fiche/TypeID/26/Ty...FUEL_TANK_97-98 Quote Link to comment Share on other sites More sharing options...
FloridaSilverBird Posted November 15, 2011 Author Share Posted November 15, 2011 Does this help? http://www.ronayers.com/Fiche/TypeID/26/Ty...FUEL_TANK_97-98 Not really. I purchased the fuel screen with o-ring from ronayers and didn't receive a spring, and I don't see an item listed which would include the spring. It looks like there might be shown a spring or something inside the fuel screen no the fiche, but it is unclear. Quote Link to comment Share on other sites More sharing options...
EVLXX Posted November 15, 2011 Share Posted November 15, 2011 It's the Petcock Assembly. I've seen this on several bikes lately.... just none of them Blackbirds. On these bikes... the Vacuum diaphragm that opens the petcock once the engine is started in the Open valve setting, is the culprit. What seems to be happening is... that something is eating away at the diaphragm, which leads to fuel leaking into the entire Vacuum line system. In the case of the Bird, that system ties into the airbox, through the PAIR system I believe. So basically, because of the diaphragm eater (Ethanol laden gas in my opinion) you need to rebuild your petcock. ... Now, since I have never cracked into a Carburated birds petcock, I don't know how it's built, and looking at the RonAyer diagram, it shows no vacuum diaphragm. So I am left to guess that all of the above is probably still relevant, but you might be looking at an O-ring or some other such rubber part, in the Fuel Petcock that was eaten by the sneaky monster. Quote Link to comment Share on other sites More sharing options...
FloridaSilverBird Posted November 15, 2011 Author Share Posted November 15, 2011 It's the Petcock Assembly. I've seen this on several bikes lately.... just none of them Blackbirds. On these bikes... the Vacuum diaphragm that opens the petcock once the engine is started in the Open valve setting, is the culprit. What seems to be happening is... that something is eating away at the diaphragm, which leads to fuel leaking into the entire Vacuum line system. In the case of the Bird, that system ties into the airbox, through the PAIR system I believe. So basically, because of the diaphragm eater (Ethanol laden gas in my opinion) you need to rebuild your petcock. ... Now, since I have never cracked into a Carburated birds petcock, I don't know how it's built, and looking at the RonAyer diagram, it shows no vacuum diaphragm. So I am left to guess that all of the above is probably still relevant, but you might be looking at an O-ring or some other such rubber part, in the Fuel Petcock that was eaten by the sneaky monster. Hm. Well I just went and opened the petcock cover and the diaphragm looks very nice and clean, and nothing wrong with the spring. Perhaps instead of eating away at the diaphragm, it got stuck in some position? On the other hand, when i bent the vacuum hose leading to the diaphragm from the engine down, it leaked out gas, so it looks like you are on the right track when you say fuel is leaking into the vacuum line system. Or perhaps this is due to gas overflowing the carbeuretors all the way up the drains. I'm not sure. Anyways, I did a little dusting, reseated the diaphragm, and put it back together to see if this is still happening--although maybe it will only happen again after i turn her on and back off. Quote Link to comment Share on other sites More sharing options...
blackhawkxx Posted November 15, 2011 Share Posted November 15, 2011 You can tell if the petcock is opening and closing by applying vacuum with the fuel line off. Quote Link to comment Share on other sites More sharing options...
FloridaSilverBird Posted November 16, 2011 Author Share Posted November 16, 2011 You can tell if the petcock is opening and closing by applying vacuum with the fuel line off. I understand how the petcock works now and after some testing it looks like it works just as its supposed to. Although when there is no vacuum and it is closed with fuel on i can blow into the gas entry and it takes quite a bit of pressure to get it open, but i can clearly feel that the rubber seal is good. So, rubber seal is good and petcock works. At least now it does. Edit: I got her to run just fine now . We will see if something happens again :icon_wall: Quote Link to comment Share on other sites More sharing options...
EVLXX Posted November 16, 2011 Share Posted November 16, 2011 Hm. Well I just went and opened the petcock cover and the diaphragm looks very nice and clean, and nothing wrong with the spring. Perhaps instead of eating away at the diaphragm, it got stuck in some position? On the other hand, when i bent the vacuum hose leading to the diaphragm from the engine down, it leaked out gas, so it looks like you are on the right track when you say fuel is leaking into the vacuum line system. Or perhaps this is due to gas overflowing the carburetors all the way up the drains. I'm not sure. Anyways, I did a little dusting, reseated the diaphragm, and put it back together to see if this is still happening--although maybe it will only happen again after i turn her on and back off. First off... if the diaphragm is bad, and it was caused by the ethanol, it will look nice and clean, and you probably will Not see any holes etc. There is NO stuck position that should let fuel go around the diaphragm. second.. Just off the top of my head, I don't know of any other way that the Vacuum system could get filled up with fuel. Every other fuel connection scenario I can come up with has a hole in it... a drain hole. Like the stuck float idea.... Carburetors have overflow ports and tubes, etc. ... Now, my guess is, it's a very slow leak, very slow. I also guess that it'll run fine, or seem fine, but your gas mileage will go to shit. I'm also going to guess you need to buy this... http://www.ronayers.com/ProductDetails/N/687/SKU/262425 ......it looks like it's an all included set. Good Luck... Quote Link to comment Share on other sites More sharing options...
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