recently I had a problem where the bike broke down and it felt like I had run out of fuel, a road side mechanic came out and was very good and traced it back to the fuel pump (it had failed) I recently got a replacement fuel pump, fitted it, and now when I try and start the bike it just chuggs a bit the backfires (the fuel pump is now pumping the fuel through again). Has anyone got an idea of what could be causing this? I replaced all the plugs on Monday and still have the same issue. the only thing I can think is that maybe I haven't sat the carbs back on properly when I put everything back together. Would this be a cause of my problem or do you think it could be something more sinister? I am getting to the point where I am starting wonder whether it is getting close to time to retire the bike. It was running perfectly before the fuel pump gave up, but the bike does now have 107k on the clock so it is getting on a bit.

Any advice would be gratefully received.

107k !
Well done that bike.
Have you checked the plug leads are on the right way?
Did you disturb anything else when you took it apart?
It's worth just going over all the pipes and plug connectors etc in case something is not quite right.