So if this is a carb /intake "upgrade" , the usual dispensed wisdom is go back to where it last worked and verify that it continues to work...then move forward...but if there is something like a bunch of janky adaptors and hoses etc etc..start there first...while issues with the starter circuit often are the problem ....two strokers work like any the other suction pump..the rising piston pulls in air which rushes over the jets.