is the nearside sprocket side bearing prone to failure on the nc30

No dave, only an overtight chain, wheelied past, or oil starvation / shit quality would be likely to cause this.
has yours actually failed ? what are the symptoms.

having trouble getting chain tensioned new c/s kit with bike on abba stand caliper and chain removed wheel spins freely no rumbling or noticable play but their is an audible click coming from the hub that will require investigation , this hub was fitted last year cleaned up s/arm and cleaned and regreased bearing holder so pretty sure its not crap inside, got a new hub with bearings still in box that i got with the other bike if reqd, was just wondering crm if they were prone to wear drive side in the same way older blades did in the sprocket carrier

not that i am aware of dave. i will say though, some of the cheap chains from the bay are complete bollox frankly. always invest in a quality chain of reputable brand over some cheap 50 quid elastic chain that doubles in length when warm and always feels like its been dragged through a sandpit.
if the bearing feels rough by hand then thats not a good sign. major job too.
get a second opinion before tearing it down or buy a second hand motor.

its the hub/chainadjuster bearing crm.the gearbox output shaft bearing ok phew ... in agreement about the cheap chains with you as the racelink one was poor[false economy] so changed it for an rk x ring believe they are o/e on some hondas along with new renthal sprox .

CRM wrote:not that i am aware of dave. i will say though, some of the cheap chains from the bay are complete bollox frankly. always invest in a quality chain of reputable brand over some cheap 50 quid elastic chain that doubles in length when warm and always feels like its been dragged through a sandpit.
if the bearing feels rough by hand then thats not a good sign. major job too.
get a second opinion before tearing it down or buy a second hand motor.

Thers a few bearings in the hub..

A double bearing and a single one.. the nc24 has 3 as theres one on the cushdrive too.. but i'm not sure if the NC30 has this?

I've changed a few in the past.. most of them appear to have failed due to crap getting in there. Maybe over-enthusiastic chain cleaning with harsh chemicals that have worked their way into the hub removing the grease?

Most of the time dave silvers have the double bearing in stock for £25 instead of nearly £50 odd :)

Phew. yeah hub bearings can go as said if grit and dirt and water gets in. also overtightened "pinch" bolt i think can cause premature wear.
at least thats an easy fix dave

thanks fellas will get on the case this weekend i got a brand new hub and bearings that came boxed with the other bike i can fit.got a bit of an eye opener with the price of it after checking wemoto site£223 eek ! see they do the bearings alone for around 60 without seals which is a bit more reasonable.

problem solved the n/s large caged bearing was shot thanks all.