Mitch, I assume bwaller is referring to "Big Benley." Yes, is she still alive and kicking?
Question for this elite group... I've repeatedly heard mention of strengthening modifications to the early racing CB750 frames. Were these done and, if so, does anyone know of any document or resource detailing those mods? Thanks. RR
I can't speak to Honda's mods, only those of our RR groups of the early 1970s...
We usually sandblasted off the paint, checked the existing welds, often improved them a bit if they were short of the full length, and then added extra plates where the engine is mounted via the flat steel triangles (front lower right, upper rear side). Mine still sports doubled plates there, today. These make a noticeable difference in high speed, sweeping turns. Some riders widened the vertical "struts" in the upper triple tubes, in non-production racing classes, by grinding out the original ones and replacing them with wider ones, about 2" wide. They said it helped in short, choppy-surfaced track turns, holding the forks straighter.
We also added and extra washer on the swingarm bolt, so we could torque it tighter without running out of threads on the bolt.
And, the engine bolts were all switched out to tougher grade 8 or 12 bolts. The stock ones are about a grade 6 strength.
We all added front fork braces. Mine was a second Honda fender brace, with slotted holes and the fender removed, fitted underneath the original one. It makes front wheel removal difficult, and limits the front tire to a 4.10 trigo or 3.25 round profile, because of clearances. But, it really helped.
The stock swingarm was good to 130 MPH, with bronze bushings and tight (0.0006") clearances. Honda sprockets, with their tapered teeth and larger-than-SAE-base-circle diameter, also helped. Timken bearings were used in the wheels, sprocket support, and front steering head, as they have tighter tolerances and harder steels than the Japanese versions.
Spokes were all torqued as evenly as possible, and wheels were trued to 5 thousandths runout, after the rim itself was trued and rechromed (the rims can runout almost .020", stock). Wheel assemblies were balanced to perfection, using stickon flat wheel weights. For a while, Yoshimura sold spokes that had beefier bodies where they went through the hubs: mine still sport those spokes. Sadly, they are not as corrosion-resistant as the stock ones were, though.
All this stuff, taken together, really made the bikes feel smaller, taut, and responsive. Riders who have ridden mine say it feels like a 450 or other small bike.
