Author Topic: C11 274 carbie details  (Read 813 times)

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C11 274 carbie details
« on: December 06, 2008, 05:31:25 pm »
From: birchyab1  (Original Message) Sent: 27/07/2008 08:54
G,day all
just put a C11 274 carbie on my 1953 C11 bike to replace the Amal 626
Have stripped this carbie down and all the jets and passages are clear
With the needle and clip,how many grooves should be on the top of the standard needle.There are five (5) grooves present,have set it to the middle oneThe reason i ask is i hope this is the correct needle,i thought there were only meant to be three grooves.
i cannot get the bike to idle,the pilot jet air screw does nothing,screw it in or out.The slide has a large cut out on the top to suit a choke which is not fitted.Have i a butched standard carbie before i go to far
regards
birchy 
 


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From: 26dlx Sent: 27/07/2008 11:06
Hi Birchy, I think the three groove needles came in on Concentrics. I know that Monobloc carb's had a 5 groove needle which gives you a better range of adjustment. The fact that you don't have a choke fitted won't make any difference as long as you have the cable hole plugged at the top. If the hole is still open then that will be contributing to the lack of idle. If you have access to BSA Gold Star and Other Singles you should be able to get the correct settings for your carb.....26dlx
 

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From: Birchy Sent: 27/07/2008 12:26
Thanks for that ,it makes me feel a bit more confident i have the correct bits
 C11 274 carbie with an air cleaner,starting set up,Needle on cente clip?This is the third one from the top
air pilot screw,1.5 turns out?
can you or do you have any adjustment on float level?
Also from the intermittent petrol leak,and being difficult to maintain a constant idle speed to allow me to set up the idle,and at times fuel comes out the tickle hole.Can you reseat/lap in the float shut off rod.Or is it just get a replacement
It appears that the carbie is flooding,stops.then floods again
regards
birchy
 

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From: mike Sent: 27/07/2008 15:06
Birch
My 274? only has one setting on the needle. Make sure the needle doesn't
have a slight bend at the notch,mine did and it made the carb fllood because
it made the float off center and it would not seat sometimes and would be
fine the next. Took me a while to find that one.
Mike


>From: "Birchy" <adrian_birch@bigpond.com>
>Reply-To: "BSA C10/C11/C12" <BSAC10C11C12@groups.msn.com>
>To: "BSA C10/C11/C12" <BSAC10C11C12@groups.msn.com>
>Subject: Re: C11 274 carbie details
>Date: Sun, 27 Jul 2008 04:26:47 -0700
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> Thanks for that ,it makes me feel a bit more confident i
>have the correct bits  C11 274 carbie with an air cleaner,starting set
>up,Needle on cente clip?This is the third one from the top air pilot
>screw,1.5 turns out? can you or do you have any adjustment on float level?
>Also from the intermittent petrol leak,and being difficult to maintain a
>constant idle speed to allow me to set up the idle,and at times fuel comes
>out the tickle hole.Can you reseat/lap in the float shut off rod.Or is it
>just get a replacement It appears that the carbie is flooding,stops.then
>floods again regards birchy
>


 
 

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From: chaterlea25 Sent: 27/07/2008 16:01
HI Birchy,
Things to check on your 274 as to why no tick over,
1)Fuel level should be in line with the bottom of the air screw, if the carb tends to flood you can lap in the needle with some metal polish or jewellers rouge NOTHING ELSE
other comment about straight needle is very valid
 
2) The fibre/paper washer that goes between the jet block and the big nut on  the bottom of the carb (the one that the float chamber bolts to)
this washer must NOT block the little hole in the jet block, or no petrol goes to the pilot mixture!!
3) Remove the jet block by warming the carb under the hot tap and it should push out
there are tiny drillings in this,one goes up to the inside of the throttle slide and the other lines up with a little hole that feeds fuel to the engine side of the carb body,
Make sure all these are clear, also the one in the body, refit the choke block and
squirt some aerosol spray up the little petrol hole in the jet block there should be a spray up the two little pilot  mixture holes
 
Hope this helps
John O R
                                       PS. ngk B7hs should be ok
 

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From: c11keith Sent: 28/07/2008 10:25
Hi Birchy and Mike,I had B awful problems with my 274 carburetter, finished up with purchasing a new float chamber £60  no problems with carb now .Just hard up, and different problems.K. 
 

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From: birchyab1 Sent: 03/08/2008 02:09
John
thanks for your comments
stripped down carbie
pilot jets were clear,lapped in float seat and it no longer floods
Washer was blocking idle hole under big nut
you mentioned float level up to idle jet screw hole
how can i check this
the bike still wont idle,idle jet makes no difference
but if i keep the float level up by tickling the primer it runs nicely and responds,  as soon as it drops to the control level the engine dies,wont idle,misses when reved
There does not seam to be any way to adjust float level,it appears to be to low.
When i pull out the idle screw ,no petrol comes out of it
regards
birchy
 

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From: Military-Ron Sent: 03/08/2008 08:25
This may sound like a silly suggestion! Stick another few litres of petrol in the tank. I spent weeks with this not enough fuel level in carb, on my Speedtwin, I knew there was petrol in tank and I could tickle it up, but being on rear stand, there just wasn't enough head of fuel??? Ron
 

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From: chaterlea25 Sent: 03/08/2008 22:45
Hi Birchy,
The hole being blocked by the washer is probably the most common problem.
I have attached a pic of an amal 276 on this there is a 2ba (????) screw on the banjo fitting where it is bolted up to the carb body, remove this and jimmy in a length of clear plastic tube, or if you can drill a little hole in a suitable threadeded piece to attach the tube to bring this up the side of the carb body to the pilot screw,
Adjust the level by carefully bending the D shaped clip on top of the float or if necessary make a new groove in the float needle as a last resort.
If there is no tapped hole in the banjo I have soldered a piece of copper tube into a spare bottom nut to take the plastic tube
Are you sure you have the correct float and needle?
I ran into trouble with fitting a type 6 on my Rudge assembled from parts, until I found out that the big nut on the carb bottom comes in different heights, so the biggest one lowered the fuel level drastically!!!!
Hope this Helps
John O R
 

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From: chaterlea25 Sent: 03/08/2008 22:48
hopefully the pic is now attached
John O R
 
 amal.jpg   

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From: birchyab1 Sent: 10/08/2008 08:30
John
just a bit of an update on progress
Measured the float bowl height with hose and fitting screwed into bottom connection on side of bowl extension arm
About 4 mm low
put an extra groove in it but had trouble stopping it flooding even after lapping in the seat.
Bought a new float needle,it had 3 grooves in it,even the lower groove was 2 mm above the old needle
Put it in set to the middle groove,but it kept on flooding,thought the tickler was hitting the float so tried it with it removed,ran alright with bowl top off,Eventually found that the new needle was 6 mm longer than the old one and when you screwed the top on it lifted it off the seat causing it to flood,its 6 mm shorter now
Anyway it seams to run alright,have not yet taken it for a test ride,seams to vary a bit in idle speed as though it gets to much petrol and then drops to the right level.I will wait for a decent ride and then readjust
I have a side stand on the C11 ,so i dont have to drag it onto the centre stand,it was not a problem with the concentric  carbie,but the side bowl one,if you put it on the side stand,which does lean quite over a bit,it starts reving due to the change in level at the pilot jet.Guess i have to live with it.
thanks for your help
regards
birchy