Carburettor problems…….I think.

928 is cast into the slide, there will also be stamped number - should be 3 for your bike.

If it will fire up when you flood it with petrol then you need a richer mixture to keep it going. Will it continue to run if you keep pressing the ticklers? Are you using the choke (indeed do you have them fitted)? You might check for blocked passages in the carburettor. Maybe check the new jets against the old ones. And check against the sizes listed in the workshop manual - just 'cos they came from Amal doesn't mean they're right.

Without a choke you are fighting a loosing battle. Any bike that starts from cold and runs without a choke is running way to rich.

Fit a choke assembly and try again.

Ditto on Commando choke requirement. I've had three Commandos ('69 Fastback , '73 Mk1a and '76 Mk3) which all required choke for cold start with standard Amal carbs for particular model , jetted and set up as per Norton specs. No chance to start without choke from cold.

I have to disagree with you gentlemen, I have/had Commandos with Mk1 concentrics and no choke slide fitted. All started without much difficulty. Might have to put a few revs on and help it along with the ticklers until it starts to warm up. But while it's not going to sit there putt-putt-ing away while you put your helmet on, it's not a problem.

More to the point, we don't know whether the OP has chokes in his carbs, perhaps he'll let us know...

Hi Ross - the way to eliminate either fuel or sparks is to get a length of tube a few feet long. Suck up some fuel and spit it down the bores with the plugs out. Replace the plugs and give it a good kicking. If it fires up and runs for a few seconds you know your ignition is work OK and your carbs are not delivering fuel to the cylinders. If it does not fire up then you know that your ignition is not working correctly or maybe sparking in the wrong place.

Good luck - Paul.

If the air slides are missing, their cable entry holes should be blocked. Otherwise there is an unwanted clear air passage right down through through the slide.

It should be obvious if the air slides are from the wrong carb body, because they'll have big gaps each side if they are.

Incidentally, when it does go, make sure you fit chromed or hard anodised slides. They'll last far longer and also reduce wear in the carb bodies.

If you read OP’s post he’s already told us no choke is fitted. Your bike must be set rich for no choke cold starts …

Hi Ross. It won't be a problem to increase the pilot jet another half a turn or more and set the throttle stop a little higher until you have the motor running at normal temperatures to then set them properly later.

I presume the carbs are not the premier type and therefore the pilot jets aren't removable, this prompts me to suggest you ensure that the fixed pilots are clear of crud. The fool proof method is to use a .016" / 0.4mm twist drill and carefully clear the jet.