Master cylinder question

[stoinkythepig]

What's the difference between a master cylinder made for a 1 caliper front brake system and one made for a 2 caliper front brake system? I'm helping someone fix up an old Honda CB450SC and it needs a new master cylinder (the original is missing). Honda no longer sells the part, but I found a new aftermarket part on ebay that would be perfect, but it says it's for a 2 caliper system. The bike only has one caliper.

[eboos]

The piston diameter of the master cylinder is the difference between a one caliper and a two caliper system. The 2 caliper system will have a larger piston.