engine problem perhaps solved.
the problems that i was having with my engines mixture might have all come down to a huge leak in the fuel tank around the exhaust pressure feed nipple .. thanks to some great advice offered by a kind member of this site Todd Marsh,, i pressure tested my fuel tank,, and low and behold, leaks near the nozzle at the top of the tank.. so fingers crossed that this will be the source of my mixture problems.
Jamessss