yamaha yb100 help

hello i have a problem with my 1988 yamaha yb100 deluxe it will usually start 1st/or 2nd kick in the morning with no choke but it will only run with the petrol tap on reserve when i switch it to on it dies after about 1-2 minutes it bogs down and cuts out

today i was riding it and just before it started raining my bike bogged down and stopped there was a bit of revs there but it was wierd they kept going up then dying until it cut out i didnt get my bike started again but i think this may be because the fuel was lowish

my bike also will idle for 10 seconds some times and dies or doesnt idle at all.

thanks for your help

edit: found out why it bogged down and cut out it was out of petrol lol