They are known to fall off. Not sure about the SC models, but the C models are very hard to find. They are frequently stolen off of sitting C's... Sorry. Check the usual suspects: e-Bay, Craigslist, etc. Cheers!
1979 CB750K (sold, 2012, but not forgotten)
1983 Kawasaki 440 LTD Belt Drive (sold, 2011)
1993 Kawasaki Voyager XII