the tranny makes a big difference - it isn't like they have the same ratio and there is just an extra gear, the gear splits are much better for street riding on the 400. I believe the carbs are different and that helps too, plus that 4 into 1 on the 400 is dead sexy. I have heard there are guys who can make the 350-4 fast, and I have a friend with a 350-4 with a yosh motor, but stock for stock the 400's extra 50cc and better gearbox (and different cams, heads, etc) just make for a better bike.
chassis makes a big difference too. The 400F is setup as a quasi performance motorcycle where as the 350-4 was a standard. I am pretty sure the 400F has more cornering clearance, better frame, better swingarm (although still spindly), and a lower stock riding position and I am not 100% sure but I think it is a lighter bike too. When you ride it, the 400f feels kinda edgy, the 350F feels like the waiting room at your doctor's office.
I don't know why honda made a 350-4, but it didn't sell well. 2 years before it got the axe.
One of my friends who also owned one used to say that it competeted with the cb400T hawk for the most UJM feeling vehicle. The only advantage it had was rev-ing the crap out of it and getting somewhere - something the hawk has yet to do. They were bikes filled with sound and fury and that's about it....no real signifiance.
I started a flap because whenever someone proposes they are valuable I say "set it on fire" because I can't tell you how many newbies I used to know who would buy these bikes (or get them for free) thinking wow how cool is this only to be disappointed the first time they rode it or tried to buy parts. They were probably the first regular production honda motorcycle that actually became hard to get parts for in the 1980-90s. It doesn't help that the bike is actually pretty - it is a piece of brie or roquefort cheese baiting a mouse trap.
I understand people get nostalgic over the bike and that is ok - nostalgia makes people save all kinds of things like garbage pail kids collector cards and edsels. I get nostalgic over stupid shit too. However if you even thinking about "restoring" one of these things because you think it might be neat - be forewarned it will cost you more than twice what it will cost to restore a mid-year cb750 and will deliver 1/16th the riding expirence.
Edited by - geeto67 on Jan 07 2008 12:19:53 PM