Misc: Carburettors Annoying 289 Carburettor Leak

Rob H

Well Known and Active Forum User
VOC Member
Just managed to get the shadow together again. All the complicated work seems to have gone OK but I have an annoying leak from the bottom of the rear cylinder 289 carb. It is not from the petrol pipe connection but seems to be coming out from the large retainer which holds all the insides of the carb (internals, needle jet etc.).

i have replaced the large fibre washer but still seems to be leaking. Any ideas on what the problem may be would be much appreciated.

My only thought is that there is a problem with the fuel level but it doesn not seem to be flooding and has not been to pieces since the bike was last used.

Regs
Rob
 

Rob H

Well Known and Active Forum User
VOC Member
Just checked the float, is the original brass type but no dents and does not appear to be leaking. Shook it, no signs of fuel inside, also immersed in hot water for a couple of minutes, no bubbles seen.
 

Dinny

Well Known and Active Forum User
VOC Member
It could be that it’s just not seating correctly, the fiber washers can be very hard. I always put a thin smear of hylomar on the fiber washers when I put it together as it’s petrol resistant.
Cheers Mark
 

yorchie

Well Known and Active Forum User
VOC Member
My comet Amal 289 was leaking and it was the needle. A little valve grinding goo smoothed out whatever was on the needle. Problem solved. Swap needles from the other carbie and see what happens.
 

Rob H

Well Known and Active Forum User
VOC Member
Thanks guys, did a bit of searching the forum and found a few related threads, now have a better understanding of what should be going on. There should be fuel in the bottom of the carb but only to a level that it does not overflow out the small hole in the side, obviously this would be equivalent to and governed by the level in the float bowl.

Will double check the "verticalness" of the carb and float bowl as this seems to have an effect. Also will use a little paste on the needle and check it is shutting off, also will apply a very thin smear of sealant to the washer, would wellseal do as well as Hylomar?

Hopefully if I do all this then the problem will be solved, really want to get back on the road asap, been too long!
 

Marcus Bowden

VOC Hon. Overseas Representative
VOC Member
Some times the level is too high and an extra washer or two lowering the float bowl will do the trick, I've made up small banjo bolts 1/4 BSF plus small banjos to replace the blanking plug that is used to drill through the float bowl arm, then cable tie a clear plastic tube to the side of the float bowl and see the level rise when you turn on the fuel, should not go higher than the word "Birmingham"
bananaman.
 

Vincent Dirk

Forum User
Non-VOC Member
Hi,

had the same problem with my old and also with my new 276. Solved it by putting
in a smaller fibre washer. Now the pressure is put on less area, so the pressure per
square inch on the washer is larger, I guess this is the reason why it is not leaking
petrol any more, now.

Dirk
 

greg brillus

Well Known and Active Forum User
VOC Member
Check your fuel taps, either plunger or lever type, if they leak internally then you will suffer leaks from the high side carb. All the Vincent folk around the globe who try in vein to stop their side bowl carb's from dripping fuel, but you can not stop it if the supply of fuel keeps coming. The float needle and seat is not good enough to stop this. Disconnect the pipe fitting off each tap and sit a small container under and leave overnight, look at fuel collected, and there is your answer. Fuel taps are a right pain............Good luck.
 

Rob H

Well Known and Active Forum User
VOC Member
I have brass type lever fuel, they seem to shut off as I had the carb disconnected and the fuel lines open, no loss / stink of petrol overnight.

Also removed the float bowl and large retainer from the bottom of the carb and connected to the fuel line to see if the float needle valve was working. It was, it shut off the petrol about 2 or 3mm (a few threads ) short of the top of the large retainer so did not overflow. Based on this the level of the petrol seemed pretty much inline with the bottom / middle of the Birmingham

Have checked the "verticalness" of the carb but difficult to judge. Will reassemble and try again with and additional fibre washer to lower the float bowl.

R
 
Top