When the 350F debuted in 1972, Cycle Magazine loved it until they took it to the drag strip with their "shop" CB350 twin. The Twin beat the Four at the strip, handily. They both make about the same 36 HP in stock trim, but the Four is almost 80 lbs heavier. It isn't a 'performance' machine.
In response to those scathing reviews (and Cycle was the original "we love Hondas" rag in those days) Honda made the CB400F, a whole 'nuther kind of ride, with lower gear ratios, a 6-speed close-ratio gearbox that is easily the best of the SOHC4 collection, and almost 10 HP more, nudging the CB550F from behind.
The 350F also came in a 250F version, all the same except the piston size, and a lighter crankshaft (and smaller valves), IIRC. This suggested just how popular the Fours were in Japan and some Euro countries, more for the cool factor than anything else: the 250 only makes about 17 HP! There were/are some awful taxes on bikes bigger than 251cc in those countries.
The 350F is probably the smoothest bike Honda ever built, when it is set up right and tuned well. It was also so insanely quiet that you could not hear it running in traffic! And, it will wind clear off the tach: so does the 400F, without a whimper. The cam on the 350F doesn't start its show until 5500 RPM, and the 400F until 7000 RPM. They live to rev!
One of the more interesting facets of the Baby Fours is their incredible durability, when compared to the Twins of the same displacement. The Fours will easily run well past 50K miles with nothing more than oil changes and tuneups now and then, while the Twins rarely reached over 25k miles without significant help. In the days of 55 MPH speed limits, the 350F/400F bikes were seen touring the interstates everywhere, often 2-up, some even pushing Windjammer fairings (I even installed some of those myself on them), happy as can be!
It took me over 35 years to finally get one myself. It's a wreck in appearance, but it looks like a gem in the rough to me: next summer it will rise again.
