The lever you are listing is a three finger BMX style lever. It will not give you that much leverage. I would check to make sure that the housing is cut correctly, ferrules in place, etc, and play with the pad clearance from the rim about as others have suggested.

Go over the rims and pads with alcohol to clean them. Also, inspect the pads for any embedded metal particles. If the rims were new on this bike, then perhaps the machined surface was not cleaned after machining and there are metal particles in your pads, causing your brakes to perform below standard. I have seen this numerous times on new bikes with machined braking surface rims.