The needles vibrate in the carbs and cause the brass jets to wear oval and cause the bike to run rich over time, took me some time to work out worn jets were causing a lot of running problem when worn, it's not only Amal carbs that do this and carbs that are hard mounted on the manifold can wear out jets, needles are harder so not much chance they wear but brass jets do, rubber mounted carbs wear less over time, but as I say full carb kits are cheap and you get everything in the kits but just got to make sure you get the jets you are running in the kits.
It also how many miles you have clocked up in those 3 or 4 years my Norton was an everyday rider most of its life so 6k to 12k mile per year of riding, the last 12 years my Norton is semi retired so not a everyday rider no longer but it taken out regularly.
Its 49+ years I have owned my Norton, I think in all that time I have learned a thing or 2 about my Norton and I say my Norton and what is needed to keep it running sweet and a one kick starter, heat also plays a part in tuning we live in a hot climate down under 9 months of hot and warm weather, and 3 months of mild winters which we are 2/3 of the way through our winter and the Norton runs ever better in the cooler days, but I also run a Lochart oil cooler all year round since 1978.
I am no tec person but I do know my own Norton and as well mates Norton's I have done rebuilds on and help to keep them running sweet, I do all my own work, rebuilds and maintenance and my old Norton has always been a runner as well very reliable, so I must be doing something right as the mates who had Commando's as well the one or 2 who still do always come back to me for help or advice, always willing to help mates and mates of mates lol.
I have also owned and worked on a few older Triumphs over my 50+ years of riding, just the Nortons are my favorite been hooked since I was 17 years old and I owned 2 new Triumph Thruxtons that seem to keep going without touching them except oil and filter changes so now only the Norton and the 2016 Thruxton in my stable of on road bikes, have a 1960 Manxman project build as well my 2007 Honda CRF450X dirt bike, always had a dirt bike since 15 years old, I just prefer British bikes over most and Honda dirt bikes and the most important thing as I get older I am still riding them all as hard as I have always rode, I be an old age pensioner in 4 months time, ride hard and live young in mind, but a bit wiser now.
Ashley (from down under and still loving 2 wheels)
