Dripping pre monobloc

[G3L1946]

Good morning all,

As the snow fell I decided to finish off fitting new corks to the petrol taps. All fine, they don’t leak. However, fuel is now coming out of various other places! Not too worried about some as a tweak of the spanner is sorting them out. The fuel coming from the carburetor itself is more baffling. After about two minutes of turning the petrol on fuel ‘appears’ to be coming from the small hole on the carburetor body ( see photo ). I’ve replaced the float bowl with the correct angled one and am thinking is something amiss there and have I done something wrong? The original fitted was angled incorrectly but, ironically, this leaking was not evident.
Not sure if this is relevant but when holding the tickler down fuel escapes from under the bowl cap. I don’t remember that happening before? It might be immaterial.
Any advice appreciated.

Thanks,

Steve

[MalcW]

No answer I'm afraid, but I would be interested to know, as 2 mates with 1930s BSAs have the same thing.

[g80csp11]

if its only when you have flooded the carb , that would just raise the float level a bit
if it does not happen when running , or stopped id not worry
mine does the same and it only caught light once when it backfired and id not noticed until flames were visible
. same bike 46 except a 500

[G3L1946]

Hi,
Unfortunately, it does it just when petrol turned on. After about a minute or two petrol starts to drip from the holes ( there is one either side ). I was rather trying to avoid pyrotechnics on the A64 to Scarborough!
Petrol only escapes the bowl lid when flooded though.


Steve

[clive]

I think the float must be sticking or not seating properly. As it did not happen before I wonder if the new float bowl is actually the wrong angle or if the seal between bowl and float needle is damaged. Why not try the old float bowl and see if it still happens. ?

[G3L1946]

Hi Clive,

The bowl is 15 degrees, the original was 5 degrees. With the original the float bowl sat at a non vertical angle which, I thought, might lead to problems ( sticking float ). It now sits vertical. In every other respect the two bowls are identical. If I can’t fathom it out then reverting to the original may be the way.
Thanks

Steve

[g80csp11]

try putting an extra washer on the connection to bowl , that would drop float level a bit . may be enough to stop problem

[G3L1946]

Hi,
So, do I take it that the ‘flooding’ is due to either a sticking needle/ float or the petrol level within the bowl being excessive?

Steve

[clive]

Hi,
So, do I take it that the ‘flooding’ is due to either a sticking needle/ float or the petrol level within the bowl being excessive?

Steve

or a poor seal between the float needle and the float bowl. This might explain the gradual time delay before the leaking starts as the fuel gradually leaks past despite the float reaching the closed position. Also make sure the clip holding the needle inside the float is not allowing it to slide past the grove.
however in my experience they do have a tendency to leak from those holes if the level is not quite right. the float has not got a leak has it?

[g5wqian]

might be the float needle seat taper is not sealing up when float goes up , i think you can lap it with some fine valve grinding paste and a cordless dril on the float shaft .
on my flat tanker i have the opposite occur where the float doesnt drop back down and i get a backfire and conk out after the fuel runs out in the bowl , i get away with it to get home by pressing the tickler every 30 secs so it will run but its a bit of a circus act doing so whilst riding it and having hand change gears and lever throttle lol .