August 2, 201214 yr It's still me...had to re-register with a slightly changed name... I just sorted a problem that caused me a bunch of headache...and probably a top end. I came across this in the early 90's when fuels were changing. I had thoroughly serviced my carb, so It was a last resort to pull it off AGAIN, but, as a last resort, I did; and I found no fuel in the bowl. The float needle was stuck in the seat...probably due to swollen rubber tip from some fuel additive or another. Watch out for it!
August 2, 201214 yr Huh! Normally neoprene does not react to fuel or almost any thing you would pour in a fuel tank I used to use a Q tip and lapping compound on the seat but toothpaste works well also
August 2, 201214 yr Author Guess what...problem NOT sorted. It ran dry today. Not the fuel tank vent, not the carb vent/overflow. Disassembly revealed everything to be moving freely, but a DRY bowl. Before I took the bowl off, no amount of tapping the body or blowing into the fuel line could force anything into the bowl. This bike is possessed. I don't need a mechanic...I need a freakin' exorcist!
August 2, 201214 yr Guess what...problem NOT sorted. It ran dry today. Not the fuel tank vent, not the carb vent/overflow. Disassembly revealed everything to be moving freely, but a DRY bowl. Before I took the bowl off, no amount of tapping the body or blowing into the fuel line could force anything into the bowl. This bike is possessed. I don't need a mechanic...I need a freakin' exorcist! Have you checked the petcock (take it out and take it apart) for junk in the screens and flow? Jon
August 3, 201214 yr Member the Q tip and toothpaste thing, could be shellac on the seat but ya good comment above, does fuel flow through the peacock? And don't neglect the float bowl vent hoses, if they are pinched or plugged then fuel won't pour, just like plumbing And make sure you bench test it before you install it
August 3, 201214 yr I take it that you have checked the floats are not sticking or the pin has moved etc? Float height adjustment and the tiny actuating tab set correctly?
August 3, 201214 yr Author Floats checked, vents checked, petcock checked.... Here's how it goes: Bike stalls...dry bowl. Take off fuel line, drain it, put it back on, turn on petcock, filter doesn't fill. Take off bowl, make sure everything is moving freely (I even smoothed the edges of the float needle). Put it back together, put on the fuel line, turn petcock, filter fills...bowl fills...bike fires right up. Ride awhile. Repeat. When the carb is off, I can turn it upside down and back and hear the floats and fingers moving freely. The only thing I can think of is, there is a slight bit of slop whee the fingers go on the pivot pin and if the fingers move in one direction, the contact the body of the carb...but that certainly doesn't seem like something that couldn't be dislodged by a sharp rap on the carb body. WTF?
August 3, 201214 yr You need to bench test it repeatedly, even if the floats are moving it does not mean the needle is Again, there could be shellac in the seat along the sides Q tip and toothpaste to polish it up then bench test a dozen times If you have access to an extra float bowl plug make up a fuel level Gauge with a little barbed spigot and a thin piece of clear hose to hold up to the side of the carb body The fuel height should be approximately level with the gasket surface I can safely say that in most cases like this people overlook the simple stuff and look for the most complex scenarios Ockam's Razor = the simplest most obvious conclusion is usually the correct one
August 3, 201214 yr Author You need to bench test it repeatedly, even if the floats are moving it does not mean the needle is Again, there could be shellac in the seat along the sides Q tip and toothpaste to polish it up then bench test a dozen times If you have access to an extra float bowl plug make up a fuel level Gauge with a little barbed spigot and a thin piece of clear hose to hold up to the side of the carb body The fuel height should be approximately level with the gasket surface I can safely say that in most cases like this people overlook the simple stuff and look for the most complex scenarios Ockam's Razor = the simplest most obvious conclusion is usually the correct one Bench testing it a dozen times with a specially-made apparatus to check the fuel height in the bowl is simple? It's a good idea, BTW, and you clearly know what you're talking about, but I've been working on these things for over 35 years, professionally at times, and I've never had to go through al that to get a carb sorted. What a PITA
August 3, 201214 yr This is the problem "hear the floats". You need the carb off and on the bench in good light to check the finer points of floats and operation of the valve. Carbs always rattle so you will "hear" things bu tit does not mean it is right. More reasearch needed I'm afraid but I reckon your close.
August 3, 201214 yr Author If there's ever been any doubt, all I've ever done is turned the carb upside down and sucked on the fuel line to be sure the needle is sealing...turn it back upright and suck again to make sure the floats/needle drops. I'd figure that several successful rounds of this would be enough to assume the float/needle stuff is sorted. Apparently not! Just because it's worked the last 2000 times on Linkert, Schebler, Dell'Orto, Keihin, Mikuni, Amal, Bing........doesn't mean it will again...I guess....
August 4, 201214 yr Jeez Charlie! What bike are you fettling with and what carb? This ain't rocket science you know! If this is a dellorto, loosen the bottom screw. If you have fuel going in and none coming out, then that needle is stuck like Chuck! And don't let anyone tell you they will not stick and swell with the new fuels. They make a new style now in this mellinea.
August 4, 201214 yr Bench testing it a dozen times with a specially-made apparatus to check the fuel height in the bowl is simple? It's a good idea, BTW, and you clearly know what you're talking about, but I've been working on these things for over 35 years, professionally at times, and I've never had to go through al that to get a carb sorted. What a PITA Ya me too, I have been a service tech and a factory service representative since the early 80's and I have seen sooo many weird one time problems that I know you are almost always on your own with these gremlins There are no short cuts and usually the Internet just takes you in directions you don't need to go It's just like riding, go back to the basics and you often find your problems on the ground floor sometimes you need someone else who knows half of what you know to come by and point out some stupidly obvious things.......trust me, I have been on both sides of this one LOL Hey you don't have a bent float pin or mabe a burr from a pair of pliers or something? These parts should be sloppy and loose, seems like wear but it's usually good
August 12, 201214 yr Author OK...this bike tipped over to the right and the fuel wouldn't flow until I tipped it over to the left. This leads me back to the idea that there's something going on with the side-to-side movement of the float fingers on the pin. Take it apart AGAIN!
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