If you are puting a new coil & cap on then it would be best to use a new plug as well, and making sure you have the correct gap. When you have the new parts on let us know how it go's and if you still have a problem. It may all so be worth doing a few simple checks before you start, make sure the battery is fullycharged all terminals clean and tight then a check of the wire- loom as it comes from the generator up to the regulator and CDI, then follow up to the ignition switch, all sorts of problems can be found behind the head light, quite often this is where a bad earth can be found, check all the connectors are clean and making a good contact, ive had my own starting problems from damp getting in to the connecter for the kill switch here. A good check of the ignition switch its self is all ways a good idear make sure there is a good earth here, a mate spent best part of a month tring to get his XR600 going in the end he took to the garage, new ignition switch took one hour and it was running. As for the fuel system a few checks here can be done to make double sure, its worth just looking inside the tank to make sure there is no crap that has built up over the years, letting fuel through and then blocking the filter, this can also be done with the carb just let it free flow out of the drain over flow underneath, make sure that the carb is balanced, ie the secound part of the carb is openning at the correct time, if this is a new secound hand carb its worth giving it a check over inside, make sure the float is set correctly set and that there is no crap in there, a tin of aerosol carb cleanner would be of help here, some times as you try and start the bike it will allow to much fuel through flooding the engine and wetting the plug, a quick inspection of the pump maybe needed but if you have fuel coming through when you try and start it then there should not be a problem as long as it is not letting fuel through when the engine is turnned off, just take a quick look at the pipe to make sure there are no holes.
its hard when your on the end of a computor to give advice, im more the hands on type so i hope some of what ive said can help, but as i said to start with let us know how you get on. Skip
Do the best you can with what you have,
A stranger in a strange land now heading North South East West to.....