It's a bad idea to use any solvent on a bottom bracket (i presume you are using Shimano HT2 cups here?) Any solvent that gets past the seals will thin and strip the grease inside the bearings containers. Any external dirt on the cups should be wiped off with a rag/dry towel. Solvents are for other parts like chains. Keep them away from anything with bearings that includes hubs,headsets,bottom brackets,pedal spindles.