I have a question about float level adjustment on the Amal 276. On starting after a proper carby tickle, the motorbike idles properly. After a good run down the road, coming to a stop the engine will not idle and dies immediately due to fuel starvation. Another good carb flooding will allow the engine to start up right away and idle. I have had the 276 apart many times, making sure everything is functioning properly. I've checked the float needle is seating well, the float is fine, fuel flow into the bowl is fine, and the slide is a very good fit inside the carb body. I assume the pilot jet flow is fine because the engine will idle properly at times. I haven't rigged a float level tester yet, but was looking at an earlier post regarding this. I'll try to get this done soon.

My question is what is the general consensus on the proper way to raise the float level? I haven't been able to find anything in all my Amal literature. Guidance on diagnosing my problem and any help sorting this out would be greatly appreciated.

Thanks!

email (option): wingco40@hotmail.com

Hi Mark..There are three different fittings that screw to the bottom of the 276 body before the float is fitted....Do you have the correct one for an M20?..
This affects the float height relative to the jets as the fittings are different lengths.
The correct one should have the hexagon used for tightening it directly under the piece that has the thread in it to screw to the carb body, with no 'neck' or reduced section between this and the hexagon.
Float height is not adjustable in the 276 with just one groove on the float needle in which to locate the float clip and thus position it correctly.....Ian

Mark, an erratic tickover is usually due to sucking air in somewhere. Is the carb flange where it bolts on dead flat. Also try taking out the pilot jet and screwing in flexible tube from a standard bicycle pump. I.e the threaded part you usually screw into the pump is the same thread as the hole where it screws into the pump. Once you have screwed it into the pilot jet hole you then havebabgreat tube to Plowright down to clear any obstructions in the pilot jet . Cheers John

email (option): Tinley@btinternet.com

Try retarding the ignition a little on the lever when ideling to see if that improves matters.

Have you got the insulator fitted between the carb and cylinder barrel?

email (option): davmax@ntlworld.com

Thanks all for your thoughts on my problem. The 276 is fitted not to my M20, but to a '37 Norton Model 50. I am certain it's not an air leak, and retarding the timing does not make any difference. Thanks Ian for pointing out that the only way to adjust float level on the 276 is with the fitting at the bottom of the carb body; I was not aware of this. I now suspect that I may have the incorrect fitting. I've attached a photo of the carburetor.

Any recommendations or leads on where one might find a selection of various fittings for the lower carb body? thanks very much for the help.

email (option): wingco40@hotmail.com

Mark I suggest you go directly to Amal with your query and for parts.

www.amalcarb.co.uk

Ron

email (option): ronpier@talk21.com

Thanks Ron, will do.

email (option): wingco40@hotmail.com

You have the correct mixing chamber nut for the Model 50 (and most OHV engines). Generally, the side valves have the shorter nut giving a higher float level as they need a bit of extra fuel to give a reasonable pick-up on acceleration.

Your bike would originally have had a Type 76 carb with the pilot air drillings in the side of the mixing chamber. The unit fitted is probably post-war as it has the fast tickover adjuster for starting which didn't generally appear on Nortons until 1946. It should be OK but it's worth checking that everything is in order and nothing silly like the early jet block or one from an 'R' suffix body.

Float chamber angle could have an effect but it looks vertical in each direction.

My suspicions would lie with the pilot air drillings and that means removing the jet block for a thorough clean of body and block. When you depress the tickler, you effectively flood past the pilot fuel feed and this would disguise the symptoms of a blocked drilling there (they are tiny and are the first place that sediment is drawn to).

Burlen / Amal can supply alternative mixing chamber nuts if necessary.

Hi Ric, thanks for your thoughts. When I rebuilt the carburetor, I took out the block and inspected and thoroughly cleaned it, so I'm certain the block must not be the problem. Just happened to run across today an article in the July 2013 issue of Real Classics on a 1936 Norton Model 18... what good luck. There is a close-up photo (below) of the 276 fitted with the short lower carb body fitting. My '37 Model 50 has the longer fitting. Just checked the Amal website and they have the short fitting available, so will order that up and see what happens.

Thanks everybody for the help.... will report back on results.....

email (option): wingco40@hotmail.com

As Rik said. The usual practice is for a SV to have the short nut and OHV the long nut. But I have found exceptions to the rules both ways in my collection. Also with regard to the drilling's also refereed to by Rik. Simple cleaning and blowing with an air line is sometimes not sufficient! If you look down the barrel end of the throat, you will see a tiny drilling which corresponds to a drilling in the jet block. It's common for this to fill with a hard residue. With the jet block removed it's quite simple to run a thin wire through them to clear them. Ron

email (option): ronpier@talk21.com