OK, so which particular "brass" is the culprit? Float valve, slow jet, main jet, needle jet, jet needle, IMS?
Or all of them? There must be many folk who for whatever reason, now run aftermarket brass. Surely not all of them would have issues?
I have a second set of carbs in very bad condition, but it appears that they have Keihin brass which would be a major task to clean....would it be worth doing so, and replacing the brass in the current carbs?
Sorry for all the Qs, but I'm trying to get a handle on "why" aftermarket brass should be a problem.
Aftermarket brass bits are often cheaper. Ever wonder why? Part of it is quality control, as in, do the parts have the original specified dimensions? Some sellers leave measurement checking to the makers. Paying someone to measure the parts costs money. If the seller doesn't check and the maker has no pre-ship check point, it is easy for out of tolerance parts to slip through, as that lowers their business overhead. So, parts sold may or may not be the dimensions Honda determined were correct. Sometimes cheap is exactly that. And, it is up to the buyer to determine if the part not only fits, but functions in the same way as original parts.
Unless the brass original parts are physically damaged or corroded, their dimensions are the same as when the bike left the showroom floor, as in "drove and operated well".
What historical record do you prefer for parts installed in your bike? Proven working, or implementing a new testing/measurement process for the unproven parts to ensure proper function?
It is my belief that Keihin, has a consistent recipe for making parts for their carbs. Or, they have a QA process to qualify parts they distribute under their company name. So, buying replacements from the original manufacturer, is most likely to get you internal parts that work the same as when the bike left the showroom floor.
Or, you can experiment with "cheaper" or easier to get parts, and measure them in detail to ensure dimensional specifications.
Your choice.
Cheers,