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Fuel leaking out of carb ?

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Fuel leaking out of carb ?
Started at 12:25am on the 13th August, 2017 by dazza
dazza Subject: Fuel leaking out of carb ?
Hi all today when I was trying to start my 350 Bullet on kick start I had a problem for the first time the bleed nipple on the carb and the carb filter ect fuel started to pour out of it with the bike not even running so I turned the fuel tap off and cleaned fuel up and then tried it again and bike started fine and run ok what could have happened as I don't want that to happen again
Posted: 12:25am 13th August, 2017
binary Subject: Fuel leaking out of carb ?
It sounds like your float got stuck up. If it sticks in the up position the fuel is not cut off by the float not coming down and cutting the fuel supply off. The float needle valve will then let the fuel flood into and out of the carb all over the place from the fuel tank. There may be some dirt in the float needle valve seat thus not letting it close with the same flooding result. If this happens again and it has happened to me in the past, turn the fuel off and then just try tapping on the carb float bowel with the plastic handle of a screw driver then turn the fuel back on again. If it stops flooding it was a stuck float and if it floods again it is some dirt or something stuck under the float needle and seat and will have to be cleaned out.
Posted: 06:56am 13th August, 2017
dazza Subject: Fuel leaking out of carb ?
Thanks for reply will try that next time
Posted: 08:23am 13th August, 2017
Revband Subject: Fuel leaking out of carb ?
It was probably a bit of crap in that "float bowel".Sorry too good to miss.
Posted: 09:03am 13th August, 2017
dazza Subject: Fuel leaking out of carb ?
Yeah thanks is it easy to clean bowl out I have Amal carb kit fitted and is it worth fitting a inline fuel filter to help
Posted: 11:23am 13th August, 2017
Exile Subject: Fuel leaking out of carb ?
Same thing happened to me. Carb off and check the float.
Posted: 01:24pm 13th August, 2017
dazza Subject: Fuel leaking out of carb ?
IMG_0352 I have this carb pictured above as this is my first time to attempt this job do I unscrew the side cover on the carb no29 in diagram and clean out the chamber and check the float out also will anything fall out lol any advice on this would be great thanks
Posted: 01:36pm 13th August, 2017
Alan R Subject: Fuel leaking out of carb ?
Hi Guys---- Hi BINARY..I think you got your description a bit back-to-front there..As fuel fills the float chamber the float rises with it and thus lifts the needle valve into the shut position, preventing any more fuel from entering..This level is designed to be just below that where the needle jet enters the carb's venturi...For fuel to continuously flood from the cab. 2 things have to happen simultaneously}---1) The float valve is permanently open, .. 2) The fuel tap has been left open.......Item 2 is self-explanatory, item 1 can be either grit between the valve and its' seat OR the float is not returning upwards ( Jammed pivot , incorrect assembly, porous / flooded float body )....A few years ago Amal supplied a batch of plastic concentric floats that had been glued together out of alignment = flooded carb !!..I can vouch for that as I was a lucky recipient of such an item and YES !!, my garage floor was swamped overnight with 2 gallons of best Arabian distillate ( Yep, you guessed it--- I hadn't turned the fuel tap off, DOH !! ).......Hi DAZZA, You show the Amal Monobloc carb ... pay attention to items}--- 30 ( gasket ) and 31 ( spacer )..Also I seem to remember that item 25 (Tickler body) can--in some circumstances --- screw down too far and make contact with the float thus preventing it from rising fully and shutting off the fuel supply....
Posted: 08:12am 14th August, 2017
Alan R Subject: Fuel leaking out of carb ?
Hi DAZZA--- just an afterthought..You mentioned "Bleed Nipple".......That's known as the "Tickler" or Flood Needle....Its' purpose is to manually push the float down and allow a small excess of fuel into the main venturi tract before starting ( Usually when cold ).. This gives a crude way of enriching the mixture for a while.....It doesn't remove air from an Hydraulic system as does s Bleed Niple...The Monobloc also has a slide valve ( Item 14 ) which is manually operated and reduces the volume of air entering the Carb. thus giving a rich mixture for starting...Sorry if I appear to be lecturing but accurate descriptions are just as important as accurate machining in Engineering........OK, soapbox stowed away and I'm back to wallpapering !!--LoL !
Posted: 08:28am 14th August, 2017
dazza Subject: Fuel leaking out of carb ?
Thanks guys I tried the bike out again yesterday and all was well again at moment without doing anything to the carb lol
Posted: 08:33am 14th August, 2017
ric Subject: Fuel leaking out of carb ?
'modern fuel incompatible with the float needle valve tip?'
always a good one to throw in to any non EFI fuel related conversation ;)
Posted: 09:35am 14th August, 2017
dazza Subject: Fuel leaking out of carb ?
Yes ric funny that the last tank I filled her up with super unleaded ? No sure if this could have been a problem should I got back to just normal unleaded fuel
Posted: 10:45am 14th August, 2017
Mark B Subject: Fuel leaking out of carb ?
Super unleaded shouldn't cause any issues that standard 95ron petrol doesn't also do. I always use a premium brand of super unleaded as it contains less ethanol than standard (if any) and is less likely to melt/corrode/dissolve bits of carburettors, fuel lines etc. Until recently I could get 4* leaded petrol in Hertfordshire - old bikes just love that!
Posted: 01:23pm 14th August, 2017
Alan R Subject: Fuel leaking out of carb ?
Hi Guys------I thought that VITON ( the rubber tip on a carb. needle valve ) was safe against modern "Petrol" ??.... http://www.martins-rubber.co.uk/blog/what-is-viton-our-essential-guide/ ( Be patient---it can be slow to load )..
Posted: 09:52am 15th August, 2017
Revband Subject: Fuel leaking out of carb ?
You re correct Alan, viton is not affected.
Posted: 12:41pm 15th August, 2017
dazza Subject: Fuel leaking out of carb ?
As the bike is ok again do I just leave it or is it worth inspecting the carb bowl to see if it needs a clean thanks
Posted: 07:46pm 15th August, 2017
Revband Subject: Fuel leaking out of carb ?
Just leave it alone they all do it occasionally, you won't find anything if you look it's gone by now.
Posted: 08:30pm 15th August, 2017
Alan R Subject: Fuel leaking out of carb ?
Hi DAZZA-----one of the better parts of an AMAL MONOBLOC design is that you can remove the float unit much more easily than it's successor--- the Concentric carb...One part of me says}---- "Leave well alone" whilst the other says}--- "Why not fit the float bowl extension unit" item 29a in that diagramme of yours......The Monoblocs suffer from cornering /banking effects due to the off-set position of the float chamber..One way over-feeds the main needle valve so it'll run rich for a while...whilst the other way momentarily starves the needle valve ie}-- it runs weak for a little while....The float chamber extention is a way of increasing the total volume in the chamber and hopefully balancing some of those errors out...
Posted: 08:58pm 15th August, 2017
Revband Subject: Fuel leaking out of carb ?
Alan, you theory is correct if the bike is stationary and you lean it over, however when being ridden centifrugal force keeps the petrol at the same lean angle as the bike.
Posted: 09:30pm 15th August, 2017
dazza Subject: Fuel leaking out of carb ?
Thanks Alan I shall do that do I just order the part number 29A and a new gasket then to fit it just turn the tank fuel tap to the off position and the undo the three screws holding the outer chamber cover on and then replace with the new part 29A and gasket then turn fuel tap back on hope this makes sense lol
Posted: 09:56pm 15th August, 2017

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