Tickover on ES2

Have you tried swapping the carbs over? That would pinpoint whether or not problem is with the carb.

One obscure problem which can occur with a 276 carb is the float can sometimes slide on the float needle - this really mucks up your carburation. Check the little sprung brass thingies on top of the float to make sure they grip the float needle properly. They can get tired after 60 years or so.

And of course those tiny little pilot airways - you have to take the jet bock out of the centre of the body to get at them. That took brute force in my case and I had to bend it straight afterwards.

Before I cleared mine there was no tickover except on full air slide - and the pilot jet did nothing at all. Not that it is very sensitive anyway. The books say 'don't use wire or you'll do some damage'. So I used wire anyway - what's the alternative?

The alternative is an ultrasonic cleaner. I got mine from Maplins for approx. £100. I've used it to clean the Mk1's off the Commando and a pair of MK2's off a Bonnie which had been standing for 18 years and looked like they'd been painted with thick varnish. All items came out spotless. The Bonnie is yet to run but the Mk1's are running very well. Highly recommended.

A lack of response to the pilot air screw invariably means blocked pilot drillings and as David says, checking them properly involves removal of the jet block.

I always pour a kettle of boiling water over the body first as the monkey-metal expands more than the brass block. It should then tap out if turned upside down over a length of wooden dowel without damaging anything.

Once the jet block is removed, you can see the drillings to the air screw and the mixing chamber quite easily.

I believe that in 1948, Norton were still using the 276 and not the 276R (Revised) used by other makes. If yours has an 'R' jet block in a Norton-type mixing chamber then your pilot air drillings may be compromised. If you have a smooth inlet tract with no diagonal boring onto the back of the jet block, then your block should have a flat machined on it with two small drillings.

Photos would help.

I did what Richard says - unscrew the base and a wooden dowel down inside the body up against the jet block and belted the rod on the floor. Didn't take long. Especially with Norton's clip fitting carb.

Should have made sure the dowel was a close fit and was dead square. And hot water first sounds a bit cleverer than my impatient approach.

But then it started easily and ran like new.

Oh - and I did undo the air screw because it had no retaining friction spring - and found it was a plain bolt and had no point. Somebody must have pinched it years ago.