MGB Zenith-Stromberg - KN filter

I just added a K&N air filter to my MGB. I recently purchased it and realized that the air pump and rail have been removed. I put on a K&N filter and now the thing is running so lean I have to have the manual choke all the way on. The car did have quite a hesitation with the original filter. Can someone point me in the right direction? I have the tuning tool for the carb, but don't just want to start tweaking. The car was just tuned up with wires, cap, rotor and plugs. Timing is ok.

Thanks,

Single Stromberg? The 'tool' you have: is it a hollow tube with a hex ended rod going through the centre? If so, using it to turn the adjuster clockwise will enrich the mixture somewhat... but it could be better for you to go right thru the carb. Kits are easy to get, and the 'O' rings in the barrel of that carb usually disintegrete if they haven't been moved in a while, and the diaphragm can rupture if the tool isn't seated correctly...