Frank,
Take everything below as my understanding based on some research, not established fact. I am no Honda race bike historian....and there has certainly been disagreements regarding the fine details of what really happened back then. I would not be insulted in the least for anyone to correct any bad info below.
The swingarm is likely a Spondon unit. Not something that would have come from Honda. It’s a little lighter than a factory arm so it makes some sense.
FWIW, the frame in question is almost certainly not a modified factory frame. It’s in all likelihood a chromoly tube frame built at the Honda racing department in Japan(or at least someone tried really hard to make it appear to be). It’s a road race frame obviously, with the lowered neck position like the Daytona bikes. It’s very likely a clone or near clone of the Daytona frames(there were only 4 frames sent to Daytona, but there were more frames/chassis/complete bikes made overall. Or this frame could have predated the Daytona frames if it was one of the Honda France Bol d’Or 69 frames or for some of the other races they competed in before Daytona(Morio Sumiya/Tetsuya Hishiki won the 10 hours race of Suzuka in 69 before Daytona as well). Honda sent complete and or partial race bikes over to Team Honda France, Bill Smith Honda, and others. Then there were the multitude of gifted and purchased 970 kits, partial kits, and individual parts (a whole separate subject) mixed in. How many in total is unknown(or if known, certainly not public knowledge). The 69 Bol d’Or 24 hours was won on one of the two works RC750s Honda sent to France before the the Daytona win. They likely had minor differences being for a 24 hour race(notice the big battery bracket behind the breather). It may well be one of those chassis. Or it could be from Bill Smith Honda’s race bikes. Or maybe from somewhere else entirely. Based on its last known location, its most likely from the Bill Smith or Honda France stuff. It could easily have been modified over its handful of years racing. Who knows...what we see now is likely only how it left the track.
The special Honda built race chromoly frames were said to all have been stamped Cb750 followed by a 4 digit number for in house record keeping(not for registration) so it’s unlikely one of the hand built privateer made Daytona clone or near clone frames that were also being made at the time to race unless it was intentionally made to be passed off as a Works frame. Only a handful of people carefully guard the Works frame numbers and fine details of the 4 Daytona bikes and others. Public knowledge would encourage those wishing to cash in by creating a “genuine Dick Mann bike” to sell for a bazillion dollars if enough people were convinced it was the genuine article.
I’d love to relocate that chassis to have it properly photographed and measured.
If anyone knows where it is, please let me know.
George
