Running Lean / Hard to start / Stalls

[Ingah]

My CB500 is once again, being a problem child. Have had a terrible time with the bike since foolishly buying it ~18 months ago, but at least in doing so it's been the best teacher of mechanics i'll probably ever have.

A month or so ago, i derestricted it, and had some good fun and games with the carburettor even then (probably irrelevant as i have used it plenty without a hitch since it was sorted out, but i'll link it just in case): http://www.themotorbikeforum.co.uk/viewtopic.php?f=5&t=30679

Now today, when i went to ride to work, the bike wouldn't work properly. It started on the choke as normal, but any attempt to use the throttle/rev it resulted in the revs dropping rather than increasing, and cutting out if the throttle was not released within a second or two. As it warmed up i gradually reduced the choke but it wouldn't idle at a constant RPM (this is fairly normal when it's less than 100% warmed up anyway though), and repeatedly cut out. On the multiple occassions i had to start it again whilst playing with the choke/throttle, starting the engine was difficult, it kept turning over for extended periods without "catching". So much so that i was concerned that the battery could run out (now on charge to be sure). At a couple of points i did manage to get the bike to revv up to 6-8K RPM (most of the time it wouldn't do this at all, preferring to cut out instead) and the choke partially on, but it would soon drop the revs and die when i reduced the throttle. I also heard popping noises etc (especially when i was able to rev it), which as far as i'm aware indicates it's running lean (so either too much air, or not enough petrol - it's got to be a carburettors-off job again )

Most people would probably have sold it on long ago, but i'm determined to fix this, and equally determined to avoid garage bills, i've had it with taking my bike to the garage now, it's just too costly.

So err... any ideas? (otherwise i'll be purely relying on the Haynes troubleshooting section)

Note: Video file showing the bike's behaviour to follow if i'm successful in getting it from my phone, converted and uploaded to the forum. Edit: Managed to get a link to it, here: http://media-convert.com/convert/?xid=12-gefklpcv (Please be patient, it is 3 minutes long).

Edit2: It's got petrol in it (at least a few litres in the tank) and i did switch it to reserve, but this didn't help (so i've left it on reserve).

[cypek]

I know my bike isnt anywhere near yours as it is 125cc chinese but I had exactly the same issues. It had problems starting without choke, and as soon as I tried to increase revs it was cutting out. Also very often it was just dying while riding and then I had trouble to start it again for a few minutes. My solution was new spark plug and adjusting petrol mix on carb. Now its like completely different bike. Hope that helps

(Spark plug was changed by previous owner for a wrong type with massive gap)