The bike ran fine, but the stock seat was horrible. Once replaced with a leather custom single saddle from Corbin, the comfort factor improved markedly.
Being the owner of many faster and lighter bikes of the era, the Honda CB1000 Custom seemed to run out of out of steam about 70MPH. Below that speed it was adequate. Major complaint was from the horrendous stock seat.
MY`82 GS1100 Suzuki was far superior in all performance related categories. The Honda was a very nice looking bike -- reliable, but not all that fuel efficient - especially at higher engine speeds.
Ten speed tranny was unique, but not all that effective.
If your CB1000C "ran out of steam at 70mph", then something was wrong with it. Mine is JUST STARTING to get her steam up in 5 high around 90 - and she just keeps pulling strong as an ox. I run out of balls long before the CB1kC comes close to running out of oomph.
Note: A Comments RSS Feed 
is available.