The BSA A7-A10 Forum

Technical (Descriptive Topic Titles - Stay on Topic) => Amal, Carburation, Fuel => Topic started by: scotty on 10.03. 2014 00:05

Title: Fuel soaked 276 question
Post by: scotty on 10.03. 2014 00:05

Greetings

Today my A10 project fired up for the first time since I got my hands on it some 8yrs ago  *roll*

I still have a few things to rectify (improve ignition timing etc) but the first priority is to stop it from potentially catching on fire.

I have a bottom feed Amal 276 that floods out of the jet block body and on to the mag drip tray  *sad2*

the carb is new and this is its first meeting with fuel.

The float needle only has 2 settings for the float height and it leaks on both settings on the centre stand

The float needle and its seat appear ok  to my poor eyes and magnifying glass but previous posts on this same subject suggest lapping in the float needle and seat to improve the seal on older carbs.

What type of product would be used for this assuming that both the needle and the seat are made of brass

Cheers

S

Title: Re: Fuel soaked 276 question
Post by: a10 gf on 10.03. 2014 00:24

Quote

the carb is new

Some ideas spring to mind. Check for impurities, bent float needle, punctured\stuck float bowl, good fuel supply (to produce enough pressure to actually fill the float chamber and keep the bowl floating!). & have a word with the supplier if nothing helps?

For eventual lapping, a careful use of the finest valve grinding paste.

Title: Re: Fuel soaked 276 question
Post by: scotty on 10.03. 2014 00:32

Thanks for the pointers  *smile*

I'll check those items.

I removed the float chamber cover.....the float was floating..I  and pulled up gently on the float needle and it stopped the leaking.

Perhaps my float isn't lifting up enough  along with poor seating  *????*

cheers

S

Title: Re: Fuel soaked 276 question
Post by: morris on 10.03. 2014 09:14

Does it have a stay up float and viton tipped needle?

Title: Re: Fuel soaked 276 question
Post by: scotty on 10.03. 2014 15:15

Hi Morris

Good point........

I called Burlen Fuels who manufactured the carb , unfortunately for me, those options are not available for the pre mono block carbies.

For anyone that finds this info useful I learned the following from the nice man at Burlen Fuels:

The 2 clip notches on the float needle are marked C & P.
C is for a Copper float
P is for a plastic float

I also learned that the correct fuel level in the float chamber should be 1 5/16 from the bottom of the float chamber

I'm going to strip down the carb and check everything before attempting another fire drill.

I will also try putting more gas in the tank and check the fuel taps for flow

Thanks for the replies

S

Title: Re: Fuel soaked 276 question
Post by: cotterpinkid on 10.03. 2014 17:47

Scotty,

This may or may not help...

I used to have a 276 on my A10 PL. Having only ever had experience with concentrics and monoblocs I used to tickle the 276 until I got fuel coming from the top of the float chamber (as you would with a concentric or monobloc) and the carb would flood excessively from the hole in the jet bloc and onto the drip tray.

Having asked the same sort of question, to the forum, sometime ago, I came to the conclusion that I was over-tickling the carb i.e. you only needed to tickle until you saw sight of petrol from the jet block and not the top of the float chamber.

http://www.a7a10.net/forum/index.php?topic=4608.msg31214#msg31214

Brian

Title: Re: Fuel soaked 276 question
Post by: wilko on 10.03. 2014 21:31

Yes, if you over tickle pre monos they will keep leaking out of the carb body until the right level is found.

Title: Re: Fuel soaked 276 question
Post by: scotty on 14.03. 2014 15:43

Well I took the carb apart today and found the source of my woes.

The main jet was not screwed in at all but just resting there  *eek*

The rest of the carb looked ok

Now mounted back on bike and no flooding except for a bit as a result of over tickling.

Thanks for the in put  *smiley4*


Scotty

Title: Re: Fuel soaked 276 question
Post by: wilko on 14.03. 2014 22:17

I don't see how that would effect the float level or flooding ?

Title: Re: Fuel soaked 276 question
Post by: scotty on 15.03. 2014 01:16

Hi wilco

you are right.....I'm guessing that me cleaning everything in the float bowl had more to do with improving the float needle seat


S

Title: Re: Fuel soaked 276 question
Post by: victortrry on 15.04. 2014 12:44

Its strange, I too have fitted a brand new 276 carby and it also leaks from the body, I have pulled it apart to see whats wrong but to no avail fitted the the 60 year old instrument and it is fine.

Title: Re: Fuel soaked 276 question
Post by: a10 gf on 15.04. 2014 13:02

Got similar problems with a new 276, R float, was flooding badly when on sidestand (quite strong lean, worn stand), ok when upright or driving, but still running far too rich whatever I tried (see my post above) + correct jet settings, am suspecting some leak body vs jet block.
I did also revert to the old carb.