Tried starting it for as long as I dared ( didn't want to burn out starter) just wasn't having any of it. Never had this issue starting it before even after carbs off and then replaced totally dry. Bike fuel tap has been HRC modded by previous owner so don't need to attach vacuum hose.

All seems a bit strange. Sorry, for my idiot questions here
Is it trying to go or not firing at all?
Are the throttle cables on the correct way around?
Is choke operating correctly?
Have you got a spark at plugs?

Also
What can is it?
What is the induction set up?

It is strange. It almost fires but just won't catch properly. Throttle cables are on correctly (new ones just fitted), standard unmolested air box and aftermarket end can. I haven't pulled plugs yet ( mainly cos front ones are a proper ball ache!) I have left bike stand now for a few days whilst I have been at the GP at Silverstone so I will continue trying to get to the bottom of this tomorrow.

It took me a while to get mine going after I had carbs off. It wouldn't start but fired a few times then nothing. Repeated attemps failed in the same manner, resulting in a flat battery. Before it was completly dead I decided to try bumping it. Took 8 attempts, but finally it sprang into life. This concurs with Cammo's reply about taking a while to get enough fuel through (although I didn't realise this at the time and the repeated pushing it up hill next to my house on my own nearly killed me).

"Trying to go" can be a symptom of fuel starvation, could also be electrical, but difficult to tell from here. What was the running status of the bike before you serviced the carbs?

If was running then chances are the fault will be with the carbs assuming that sufficent fuel has got to them.
If non-runner then you could have some other issues to sort out as well.

From what you say it sounds like you have a spark at plugs. If they are unknown, then may be worth checking them for condition, replace if worn or damaged, or if ok clean and regap. If you already know the condition & age of them then probably not worth taking them out.

Await your reply/feedback from you before I ramble on anymore.
Anyone else have any ideas?

Bike was running and would start up with no issues only took carbs off to examine to try and remove the hesitation and rough idle when it was running. Plugs are brand new plugs so can't imagine they have fouled/are causing issue. It really is strange only thing I can think of doing is adjusting mixture settings but surely set at 2.5 turns which they are currently the bike should start. I assume the more turns out the more fuel added to the mixture? It really is a puzzler......

does it start with a spray of carb cleaner at the airbox?

Try turning your pilot screws back in...you might even try setting them to 1.5 turns out.

@fasttom - so have you got to the root of your problem yet?