carbs

[paulmceleney]

ive changed the o rings that are on the drain off screws and petrol is still leaking can anyone help thanks paul

[Garn 1]

Paul, are you sure the leak is from the drain screws? Another place that the petrol can leak from (in close proximity to the drain screw) is the overflow brass nipple. I have seen these get a longitudinal split or crack hardly visible to the naked eye.
RegardZ.

[paulmceleney]

thanks garn1 i will have a closer look i thought i would post this question before i put some silcone on the thread ,i have four sets of carbs in boxes and they all leak is this a fault with these bikes or just my ive got to fix this little problem the petrol fumes are upsetting my asthma please anyone do reply thanks paul

[Mick Hayward]

I've had a similar problem. the brass overflow pipe in the float bowl had fractured causing constant flooding of the carb.

Regards

Mick

[Taffus]

on all the older bikes i have had its always been the float valves needed replacing. they seem to fail to seal when they get older.....

[Steve S]

Paul,is it just one carb leaking or all of them? I would be surprised if all four were cracked,are they the correct o-rings? we use a spray on developer at work which allows you to pinpoint the leak from the staining on the powder,just trying to think what you could use instead (talc powder is a possible solution ).
Good luck, Steve.

[Garn 1]

SteveS, I also would be surprised if all the overflow pipes were fractured the way described previously. It is an unsual but a real problem that does occur. I am please Mike H has also seen it, otherwise I would be "one-out". It was terribly hard to isolate where the petrol was leaking. It is likely to be only one float bowl leaking, if indeed it is the problem.
RegardZ

[Kev1R]

I too have experienced the longitudinal split or crack hardly visible to the naked eye along the brass overflow pipe. Until now I thought I was the only one! I did manage to get hold of a replacement carb bowl - courtesy of Mr Marsden.
Just out of interest - Is anyone aware of a means of repairing the split?

[paulmceleney]

steve two are leaking, the o rings i brought a complete set of o rings from screw fix for 9.75 with 419 o rings the good news is ive got plenty off spares

[Mick Hayward]

Hi Guys

I was really surprised to find this type of fault. Origionally 2 carbs were floodiing and 2 were bone dry, obviously a float valve/seat problem and a cosequent strip was required. I only noticed the break in the overflow pipe on reassembly. It just fell off. Tried to remove the old nipple but couldn't do it. Am getting a replacement float bowl now. I think in the case quoted I would go for float valves and seats. Chances are something else is gummed up as well.

Regards

Mick

[Rich]

I too have experienced the longitudinal split or crack hardly visible to the naked eye along the brass overflow pipe. Until now I thought I was the only one! I did manage to get hold of a replacement carb bowl - courtesy of Mr Marsden.
Just out of interest - Is anyone aware of a means of repairing the split?

Just run some solder down it with an iron?

Press some plastic pipe over it to seal it as long as it isn't all the way down?

Pull the old one out and put a new piece of brass tube in it?

[Magnum1]

Just a thought - you might want to check the O rings. They are complex little buggers. If not designed for petrol, they will perish and leak, or even worse, gunge up your carbs. For the sake of a couple of quid I would always use proper jobs.
Rod

[paulmceleney]

thanks i was told this before by someone that lives near me ,but i thought they might of been talking bollocks that you had different o rings that need to be petrol resistant if used in a carb iam going to have a good look at them tomorrow