Andrew_Heathwood

Hi Andrew. Amazing timing. I don't ride very often but I did want to attend a gathering on Sunday. Thought I'd better give the Commando a once over and a warm up on Friday. Nothing but pops and bangs and a sore knee. Attacked it with spanners yesterday only to find exactly what we are talking about. The carbs were new in 2014 to complete the restoration of a rolling wreck. I took it to the IOM in 2015 to ride a TT lap, something I promised myself in 1972! Glad it didn't happen there.

Keith Rayner

Wow, that has never happened to me! Which in itself is very odd â? Is it possible that the spring has 'picked up' the clip while the slide was being installed? The needle's wobbly, and (in my experience anyway) rarely goes straight into the spray tube without encouragement â of course the slide just drops in once the needle's home, but I can imagine the clip becoming displaced if the slide's pushed down before the needle's home â?? Sorry, I don't mean to insult anyone's skills or intelligence, just, wow! Have I been lucky, or what?!

It's occurred to me before that this constant needle jet wear and a few other things besides could be avoided if the needle were locked into the slide, e.g. with a grub screw, per the Stromberg 150CD carb on my Triumph Herald â then things get a bit more complicated because the needle jet has to be centred on the needle, but it's super easy and only takes a couple of minutes or five to do. Ok I think I'd solved that one when I got to 'a bit more complicated'. Mind you, a Stromberg 125CD, with a 31.75mm choke, might be an interesting single carb option for an 850 Commando, I wonder if anyone's ever tried it â? I might, if I had the facilities and nothing better to do! Dead easy carb to maintain.

Hello All

Thank you for starting this thread and replying.

We now have a total of 5 known cases where the needle clip migrating up the spring has been known to occur. Probably not enough to make a case to Amal for improvements.

I have a lot of experience of working with Amal Concentrics and back in the 1970's owned three different bikes fitted with them. On one of these bikes I covered over 40,000 miles refurbishing the carbs twice. I never saw the problem.

I suspect that a minor change has occurred in manufacture of the spring and/or needle retaining clip over the years making the problem more likely to occur. I have some old Amal parts to compare with and will be examining these further in detail. This looks to me to be the most likely cause of the problem.

Thanks again

Andy

This cannot only be a Norton issue, can it? I'll go and look at some of the several Amal springs I have buried in the shed. I wonder if the shape of tip of the last coil changed? Heavier springs have ground flat ends. I just fitted lightweight (Trident) springs to my twin concentrics but haven't tested yet. Maybe I have something novel to look forward to? The new springs are lighter but they also seemed more prone to buckle sideways within the carb. I wonder if that's part of the issue? The two I took out were different ages, and they were also different from each other.