Hi thanks for the advice, have checked with previous owner and turns out the main throttle spring above slide had been modified and halved in length to make it lighter. It measures 55mm or 21/4" in length. This may well be the problem but have checked all jets etc again and given a good clean. New spring on order.
The float height was a little high so tweaked that as per splat shop pics. Have checked with fuel and seems ok, not overflowing.
The main jet is 128
pilot 48
Needle JJH
slide 4
Needle setting second from bottom out of 5
Mix screw 1 turn out from full in
Not sure if these are standard settings, any advice would be good.
When I get it all back together will test for leaks around manifold etc if problem persists.