Simon TDM850

Thanks for the replay I'll start to have a look at the things you've suggested.

I have a 1992 TDM 850, a bit of a wreck that I want to get running and perhaps customise. I have got it to fire but it is very hit and miss, will fire better if I take both plugs out and clean them. After I have attempted to start for a few turns if I take the plugs our and test them against the head they wont fire, or there is a rouge spark; so to the body of the plug. cleaned they then spark properly, put them back in and it may fire again. when it does fire it is back firing and poping and banging. Is this most likely timing or fuel/air carbs or electrical where do I start? Thanks