What you are looking at is somewhat of an oddity. Most people likely do not even know this model existed in the Bimota lineup - probably because it didn't. Whereas the HB1 was officially a frame/suspension/bodywork kit designed around the Honda CB750, the HB1 350/400 provided a shorter list of components designed to augment Honda CB350 and CB400s. The smaller kit did not provide a new frame (which was the major cost associated with a Bimota offering). Instead, the smaller HB1 model provided some bodywork and a swingarm which were meant to augment the performance of the smaller Honda fours and relied upon the stock, Honda chassis.
Like all early Bimotas, the HB1 350/400 components were delivered separate from the remaining pieces necessary to build a complete motorcycle. The buyer was expected to supply a suitable donor machine which would then be utilized as a parts bike. Not only that, but the buyer was expected to build the bike - or at least hire a competent shop for assembly purposes. In the case of the 350/400 kits, the donor machine WAS the base motorcycle, and buyers had their choice of a few different Honda fours from this period. Of the handful of kits that were produced (numbers are *extremely* hard to verify in this case as no frame numbers are associated with the pieces), most appear to have been built on the CB400 Four. This example utilizes a CB350.
From the seller:
Up for No Reserve auction is this nice example of a rare Honda/Bimota HB1 350. Produced in very limited numbers (approximately 10), the original HB1 was based on a Honda CB750 and all were built for the track. However, Bimota also produced a handful of kits that fit CB 350 and 400 fours. The kit consisted of the tank, bodywork, swingarm, and a couple of other odds and ends. This particular machine started life as a European market 1972 CB350, and one of the aforementioned kits was added later on. Generally speaking this bike shows well, and its bodywork's aging paint is in very good condition.
This motorcycle has been imported from the U.K., and was test ridden in Yorkshire. It preformed well, and the engine pulled linearly through the power-band. The auction's winner will be provided with British ownership paperwork, a dating and authenticity letter, and import documents.
This is an excellent opportunity to augment your motorcycle collection with a sharp looking rarity for a small fraction of the cost of the factory original HB1s.
Make no mistake - Bimota started life out as a small-bike racing company, and built successful frames and components for 350cc racers. Thus this was not really a departure for them, but rather a stepping stone to help finance the bigger, more ambitious projects. As such, this smaller Bimota-outfitted machine is both a tribute to the beginnings of this legendary company as well as a more affordable alternative to the models that would follow. The build itself looks good, and provides a proper cafe racer stance that nicely compliments the Bimota name, logo and colors.
A full HB1 750 build is something reserved for the wealthy - at auction you can expect one to easily cross the $75,000 USD threshold. The 350/400 kitted Bimota will be much, much more affordable. Sure, it's missing the hand-welded trellis frame. Yes, the bodywork is a bit spartan and has not aged particularly well. And let's face it: the Honda CB350 - while a fine motorcycle in its day - is never going to haul the mail with much gusto. All that adds up to a very rare set of pieces that will likely go for a bargain. Bidding on this no reserve auction started down in the basement (99 cents) and is climbing quickly from there. Lots of time left on this one, so watch it carefully; you may be able to score yourself a very rare, Italian deal. Good luck!!