As per my other posts regarding fuel problems.
Go to the source first.
If you had a 1 gallon can and soldered an outlet pipe in the bottom and hung it up some where above the carb with fuel in it and block the vacume pipe
then the bike would run ok. Yes No? try it any old container that can be hung up with a pipe and petcock in the system. also helpful gadget when your working on the bike and dont want a huge fuel tank in the way also good for checking fuel consumption. Drive until it runs out how many miles/klm's have I done
Two things:- this can be done on the bench
1. drain the tank and remove the fuel cock check that there are no flakes of plastic or other junk that are interfering with fuel flow. Check the fuel cock that nothing is blocking it
2. put fuel in the safari tank of course the less air in the tank the better as the fuel will probably pull a vacum.
observe that you have a good flow from the petcock. Try this with the fuel cap secuerly in place and see how long the fuel runs for. if it is a good flow for a minute or two and slows down or stops remove the cap and see what happens alowing the fuel to run all the time.
they are the two main things now follow the system to the carb and ensure that nothing is blocking it there , I am a big fan of filtering so check any in-line filters and if not fitted .. fit one
Hope this helps
Il be watching the posts so if there are other things that younotice please let us all know