Oem Part Numbers: A Vs Ac

So what's with OEM motorcycle parts being listed for A or AC models? I presume one is a California emissions thing so the parts are different?

I encountered the same question when examining the Partzilla OEM fiche. I called a customer service rep and he verified the AC designation is for Calif. machines. A for all the rest of us.

Those are "Area Codes", which relate to the geographic market for which a particular part was intended to be sold.  Some others include CM for Canada and U for Australia.  Back in the 1990s the Area Codes were fairly constant, but with the increasing differentiation of model specifications for various worldwide markets, and especially optional ABS, Honda began to use different letter codes each year to indicate the intended market and the presence/absence of ABS.  As a result, apart from the usual Area Codes mentioned above, be aware that some will change from year to year (especially re ABS), so you may need to look at the "key" in the front of each parts catalog to know for sure the meanings of the Area Codes used in that particular catalog.

Area Codes are used in the parts catalogues (microfiche)  in relation to parts, but the same geographic-related information is also included in the VDS section of the VIN on each bike.  Honda reports this information to the government each year, which resulted in a somewhat amusing situation back in 2004, when Honda incorrectly reported to the California DMV that certain ST1300 ABS models were actually off-road motorcycles!

Ciao,