There are allready a lot of questions about the leaking carb, but my question is: what is the level of the gas after the flaot bowl when the needle is in the close or up position?
When I take of the body from the union nut, is it possible to see the level of the gas?
And how much is the weight of the bowl? Is it around the 43 grams?
Richard
email (option): bsa-m20@libero.it
Richard,
I have just stripped, cleaned and fitted new gaskets to my carb and the first time I turned the fuel on it leaked.
Didn't leak before i stripped it! Fuel was weeping out of the mixture chamber union nut (screws onto bottom of body). Taking the top off the float chamber I could see the fuel level was over the float so guessed the float needle was dirty. I stripped it down, emptying the carb of fuel, and cleaned the needle with some fine 3M Scotchbrite . After rebuilding the carb again I left the float chamber top off and turned the fuel on. That way I could see the float chamber fill with fuel and raise the float. The fuel stopped just below the top of the float, maybe 5-6mm below. That way I knew the needle was now doing it's job.
Seems to work ok now although if I 'tickle' the carb too much at startup there is still a small witness of fuel.
Stuart
ps: I'm new to this period of bike so someone with more experience will probably come along now with a spot on answer to your troubles. I'm learning as I go along.
email (option): stu.gibbins@btinternet.com
There is a thread where I posted a picture of a temporary sight-tube arrangement to check float level. The fuel should be just below the top of the spray tube, so roughly half way up the pilot adjuster screw.
I had to use a long mixing chamber nut to bring my level down sufficiently.
http://pub37.bravenet.com/forum/static/show.php?usernum=3155626639&frmid=16&msgid=1224504&cmd=show
I removed the ball from a metric grease nipple and screwed it in finger tight with the standard fibre washer. A clear plastic tube then fits easily over the nipple. If you try it, nipple size will depend on whether you have an early or late float chamber (M6 or M8 should fit).
I have just stripped, cleaned and fitted new gaskets to my carb and the first time I turned the fuel on it leaked.
Didn't leak before i stripped it! Fuel was weeping out of the mixture chamber union nut (screws onto bottom of body). Taking the top off the float chamber I could see the fuel level was over the float so guessed the float needle was dirty. I stripped it down, emptying the carb of fuel, and cleaned the needle with some fine 3M Scotchbrite . After rebuilding the carb again I left the float chamber top off and turned the fuel on. That way I could see the float chamber fill with fuel and raise the float. The fuel stopped just below the top of the float, maybe 5-6mm below. That way I knew the needle was now doing it's job.
Seems to work ok now although if I 'tickle' the carb too much at startup there is still a small witness of fuel.
Stuart
ps: I'm new to this period of bike so someone with more experience will probably come along now with a spot on answer to your troubles. I'm learning as I go along.
When you tickle the carb you are meant to depress the knob until petrol just starts come out, so if you see a little squirt of petrol coming out of the tiny hole on the top of the float bowl this is normal, as long as it stops when you remove your finger. I find that the BSA carb likes a lot of tickling, even when it is hot as sometimes it gets too hot and some of the petrol in the float bowl evaporates. The carb is meant to have a tufnol insulator fitted, but even with this it can still evaporate so I always give mine a quick tickle even when hot
email (option): davmax@ntlworld.com
Does somebody knows how much is the weight of the float bowl?
Here is a PDF about the Carb:
http://matchless.rhobbs.co.uk/downloads/Amal_Carburettor_Maintenance_and_Servicing_-_Issue_33_-_Classic_Mechanics.pdf
Richard
email (option): bsa-m20@libero.it
When you tickle the carb you are meant to depress the knob until petrol just starts come out, so if you see a little squirt of petrol coming out of the tiny hole on the top of the float bowl this is normal, as long as it stops when you remove your finger.
Dave, that's what it did before I overhauled the carb. But now when I tickle it petrol weaps out of the mixture chamber thread at the bottom of the body before I see the little squirt. Is that just a case of bad sealing of the nut against the body?
Stuart
email (option): stu.gibbins@btinternet.com
Yes, they do tend to leak from there, the Amal gasket set's fibre washer appears to be the main culprit out of all the gasket sets you can buy. You can give the spanner a fair old swing without worrying about the thread, you'd have to be a gorilla to strip it! It can also leak from the thread on the bottom of the body (or appear to be) but in reality it is more than likely leaking through the hole at the side of the body, this is normal when you tickle it, as long as it is not leaking from there while the bike is running or at any other time when you've stopped
email (option): davmax@ntlworld.com
Thanks for that Dave. I'll give a good swing on the nut and try that, seem to remember it being tight when I took it apart. Once the bike is running it's fine, no sign of leakage.
Stuart
email (option): stu.gibbins@btinternet.com
As i've stated before, when you tickle these carbs they will contiue to leak until they find the correct float level. So don't assume it's a faulty seal so soon. Went through all this with a B31 until it clicked.
I have bought a new fiber gasket.The new fiber gasket is large as the nut, but a bigger hole inside. Outside is 32mm and inside is 26mm. Yo don't need the force of a gorilla.
It's not leaking anymore until now.
But still I want to know how much is the weight in grams of the brass flaot chamber bowl. the bowls are for 276 type all the same.
Richard
email (option): bsa-m20@libero.it
Do you mean the float or the bowl / chamber ?
If you mean the float, Amal never listed the weight and I certainly don't have a balance capable of measuring it accurately. If it doesn't sink or draw in liquid in a bowl of boiling water then it's OK.
The weight will depend on how often its been repaired and how much extra solder has been applied. New nylon floats are available (with a different float needle) if you have doubts about yours.