I'm so pleased to have a working bike the public humiliation is definitely worth it Thanks for the reply

I've finished my rebuild, still work to be done but given a lack of expertise am quite pleased to have got this far. Previously (years ago) the bike needed very little / no choke to start and certainly not when running. Now it needs full choke to start and will not run with the choke off even after ...

Many thanks for the responses, the job is bigger than I thought. I'll weigh up putting it back together with the wear to the existing guide against finding a engineer to install new ones for me. Thanks again.

The best option seems to be the easiest and cheapest, sold! Thanks

First time dismantling a motorcycle engine (initially to change head gasket), and now feel quite foolish as I realise the "channel" I mention is actually the valve guide and not an integral part of the cylinder head. So next stupid question, assuming I can source a new exhaust valve and guide how do ...

Thanks, the valve clears fine but it looks like the end of the channel has started to flake off, I suppose it could be a lot of soot, didn't want to clean too aggressively in case it is delicate. It seemed to work before so will give it another clean and put back together, thanks again.

The channel for the exhaust valve on my NH350 is quite badly corroded, as per the pic. Can't see it causing a running problem but is this otherwise normal?

All - thanks for the advice, this is an excellent forum. Off to invest in a better set of sockets

Socket I'm using is 3/16 WW which seems to fit...

Pic attached