recently my Nc29 has become a bit jerky at low speeds does this indicate dirty carbs or would a dyno tune sort this out ? also how easy a job is it to clean the carbs ?

could be a clogged jet...
take it somewhere private, warm the bike up.. and give it a good thrashing!!! this sometimes clears the jets...

if that doesnt work.. strip and clean the carbs.
being set up on the dyno would be a benafit as well.. but not everyone can afford it.

Have you checked your chain recently? it could be loose.

+1 For chain adjustment.

It always astonishes me when road bikes go past how many of them I can actually hear the chain rythmically tighten and loosen as they go.