CB350F Fork conversion

Izzy,
I believe a 400f cylinder will fit on the 350. I am not sure the 350f cylider walls are thick enough to bore to 400. The 350 has a 5speed trans and the 400f a 6 speed. The 350 and 400 should use the same exhaust. The 500/550 are different. The front forks on the 350 and 400 are not set up for dual calipers. It is also difficult to mount a second disk to the stock hub. You would need to do some machining to make it work. If you want dual disks then I would go with a different front end. Personally I think the 350F has one of the best gas tanks for the cafe look of that vintage Honda.Finally, if you remove all the covers and crap off the 350F front forks, they are the same as the 350 twin and 400F front forks. They are definatly usable on the street and many of us have raced on them.
Good luck and ignore the stupid stuff most of these fucktards(I love that word) have to say since most of the smart stuff is really good.

Ken

AHRMA 412
Vintage racing - old guys on old bikes

Oh Yeah, the 350f and 400f are only kinda doggy. At lower revs, they just don't make any power, but if you keep the RPM up between 7500 and 10000 they are ok. The problem is that if you ride them on the street that way it gets really tiresome and loud. They are actually better on the racetrack than on the street. The 400f has more bottom end from the extra 50cc so is a better street ride. More power, such as from pipe, porting and 550 or 750 carbs, (those things all work), won't make it any better on the street unless you enjoy a loud peaky screamer( insert sexist remark here). If it were mine, and I am thinking about one, I would go with an older cafe look with 4 into 4 black megaphone exhaust, stock tank classic glass seat drum front brake and clip-ons. It would look cool.

Ken

AHRMA 412
Vintage racing - old guys on old bikes