Have refitted the carbs to my A4 but find that they are all leaking, seemingly, from the base gaskets. When I bought the bike in Jan I noticed that there was some petrol on the crank cases below the carbs.
I have tried both the original and new gaskets and both are allowing petrol to leak. I am assuming that it coming from the base gaskets?
Is this a common known problem with the A4 26mm carbs or is it actually leaking from another source?
Checked the levels in all the carbs before fitting and they were all around the 4 mm level.
Any advice appreciated.
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Leaking Carbs
Moderators: KeithZ1R, chrisu, paul doran, Taffus
Tank was cleaned when I first got the bike and before I stripped it down, so should be OK. All the jets and float valves were removed and ultrasonically cleaned before the carbs were re-built. Valve tips no wear marks on any of them and the levels checked individually and were all around the 4 mm below the mating surface, so at a bit of a loss.
Will re-check levels now they are on the bike.
Did remove one bowl and checked that the valve stops the flow, which it did but can't assume that it is stopping every time but that all seem to be leaking and were before I bought it seems to be something fairly fundamental?
Will re-check levels now they are on the bike.
Did remove one bowl and checked that the valve stops the flow, which it did but can't assume that it is stopping every time but that all seem to be leaking and were before I bought it seems to be something fairly fundamental?
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keith mayall
- 100Club
- Posts: 151
- Joined: 1st Jun 2014
- Location: MANCHESTER
leak
are you sure its from the bowls..check the tee piece where the fuel hose connects.the orings split.
Whilst I had thought the leaks had been stopped by bending the tabs up a bit more it clearly has not.
Seemed that there were some leaks from the 'T' piece nipples so I have fitted some new ones.
Have carbs in a vice being fed from an auxiliary petrol supply. The 'T' pieces are not leaking yet despite all the levels being at least 4 mm below the bottom face of the bodies they are all leaking between the top face of the bowl and bottom face of the body, well that is seemingly where they seem to be leaking as petrol is wet around the joint.
How can that be when the levels are below the joint faces?
Anybody have any suggestions as this driving me nuts.
Seemed that there were some leaks from the 'T' piece nipples so I have fitted some new ones.
Have carbs in a vice being fed from an auxiliary petrol supply. The 'T' pieces are not leaking yet despite all the levels being at least 4 mm below the bottom face of the bodies they are all leaking between the top face of the bowl and bottom face of the body, well that is seemingly where they seem to be leaking as petrol is wet around the joint.
How can that be when the levels are below the joint faces?
Anybody have any suggestions as this driving me nuts.
Surely there is a bowl overflow pipe at base of each bowl ??
If bowl level is getting too high - i.e.. towards the joint between bowl and body - then fuel should come out of these overflows first.
That is what they were designed to deal with.
When you set the float levels does the measurement stay constant over a period of time - or is there a gradual fill effect ??
Try emptying some out of the drain plug to make sure it goes back to the same level a few times - just in case you are getting an odd reading.
I agree with bench testing the carbs on a petrol bottle tank supply - it is far easier to spot where the leak(s) are -normally.
Also if it is coming from same place in all four carb bodies it is unlikely to be a blockage or crack in a carb body or a sticking float needle.
Will watch with interest to see what is the culprit.
From Mark
If bowl level is getting too high - i.e.. towards the joint between bowl and body - then fuel should come out of these overflows first.
That is what they were designed to deal with.
When you set the float levels does the measurement stay constant over a period of time - or is there a gradual fill effect ??
Try emptying some out of the drain plug to make sure it goes back to the same level a few times - just in case you are getting an odd reading.
I agree with bench testing the carbs on a petrol bottle tank supply - it is far easier to spot where the leak(s) are -normally.
Also if it is coming from same place in all four carb bodies it is unlikely to be a blockage or crack in a carb body or a sticking float needle.
Will watch with interest to see what is the culprit.
From Mark
Z1-R D1, Z650 B2, Z1-B & ZRX 1200 A1P Catch 'em if you can at www.Zedrider.co.uk
If it's not incorrect heights, three separate things you may have already checked but have caused this issue for me;
1. Fuel tap supplies fuel when engine isn't running (on a vacuum system) causing bowls to fill.
2. Needle valve/seat is worn so fuel continues to fill the bowl as above.
3. New gaskets aren't 100% effective unless soaked in fuel before fitting (strange but true).
Good luck.
1. Fuel tap supplies fuel when engine isn't running (on a vacuum system) causing bowls to fill.
2. Needle valve/seat is worn so fuel continues to fill the bowl as above.
3. New gaskets aren't 100% effective unless soaked in fuel before fitting (strange but true).
Good luck.
1979 Z1000ST
Levels were always coming back to the same, around the 4 mm level. With them in the vice I noticed that it was weeping around one of the fixing screws.
Removed the bowl and on inspection of the bowl face there were scratch marks going across the face of the bowl as if somebody has tried to linish it? You could feel them with you nail. They were all the same so thought that the fuel was creeping up to the gasket by capillary action and then tracking through the scratches?
Anyway, spent a couple of hours removing as much of the scratches with some wet and dry and put them pack together and over the next couple of hours there were no leaks, so problem solved!
Left it over night and three of them were not leaking but one had started to so checked level, OK, but then fuel started coming out of the overflow pipe and on checking the level it was now above the body line. However, it would overflow for a few secs and then stop only to go through the same cycle from time to time, this is with the fuel supply tap to the carbs open.
Changed the valve and seat with a new one with some kits I had bought, solid valve tip not rubber tipped, and exactly the same happened, initial level OK but then coming out of overflow. Bent tap up a bit and now no flow. Bend it back to get flow and the same problem occurs!
Looks like all 4 really have the same problem. Initial level OK but then they just seem to creep up with either the original, history unknown, rubber tipper valves or a new replacement solid metal tipped valve.
If I bend the tab to get the initial correct level it then creeps up and overflows if I bend the tab up just marginally it stops all flow.
I'm at a total loss at the moment and run out of ideas?
Anybody know of somebody in the Eastbourne or surrounding area of East Sussex who could have a look at the carbs as I am going round in circles at the moment?
Removed the bowl and on inspection of the bowl face there were scratch marks going across the face of the bowl as if somebody has tried to linish it? You could feel them with you nail. They were all the same so thought that the fuel was creeping up to the gasket by capillary action and then tracking through the scratches?
Anyway, spent a couple of hours removing as much of the scratches with some wet and dry and put them pack together and over the next couple of hours there were no leaks, so problem solved!
Left it over night and three of them were not leaking but one had started to so checked level, OK, but then fuel started coming out of the overflow pipe and on checking the level it was now above the body line. However, it would overflow for a few secs and then stop only to go through the same cycle from time to time, this is with the fuel supply tap to the carbs open.
Changed the valve and seat with a new one with some kits I had bought, solid valve tip not rubber tipped, and exactly the same happened, initial level OK but then coming out of overflow. Bent tap up a bit and now no flow. Bend it back to get flow and the same problem occurs!
Looks like all 4 really have the same problem. Initial level OK but then they just seem to creep up with either the original, history unknown, rubber tipper valves or a new replacement solid metal tipped valve.
If I bend the tab to get the initial correct level it then creeps up and overflows if I bend the tab up just marginally it stops all flow.
I'm at a total loss at the moment and run out of ideas?
Anybody know of somebody in the Eastbourne or surrounding area of East Sussex who could have a look at the carbs as I am going round in circles at the moment?
I have had similar problems with my A4. I removed the No. 2 float chamber because it was dumping fuel out of the overflow, and found a load of dirt in it, so cleaned it out and that cured it. Then No.1 started overfueling causing very low power, and 12 MPG 
So I removed the float chamber and found dirt in it 
I eventually drained the tank, then rinsed it out with petrol, stripped down the fuel tap, cleaned all of the bits, then replaced the fuel pipes to the carbs along with new filters, removed the carbs and stripped them down on the bench.
Made sure everything was super clean, then put it all back (float levels were all around 3 - 5mm.
Overkill perhaps, but it was getting on my nerves. Just going for a cruise about for an hour or so - I'll let you know if it worked when I get back
Richard
So I removed the float chamber and found dirt in it
I eventually drained the tank, then rinsed it out with petrol, stripped down the fuel tap, cleaned all of the bits, then replaced the fuel pipes to the carbs along with new filters, removed the carbs and stripped them down on the bench.
Made sure everything was super clean, then put it all back (float levels were all around 3 - 5mm.
Overkill perhaps, but it was getting on my nerves. Just going for a cruise about for an hour or so - I'll let you know if it worked when I get back
Richard
Somewhere, over a rainbow, weigh a pie.
1976 KZ900
1976 KZ900
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