Honda CB750 Sandcast

Rod differences in Castings between early and late sandcast, Crank Grub Screws

vnz00 · 1 · 1020

vnz00

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Hi all,
I haven't paid much attention to the rods and crankshafts in prior builds so Im hoping someone here might be more attentive!

Im putting together internals for a build.  Ive bought a set of Pre-17000 (c.12000evin) diecast rods which dont have the changes of the later K0 onwards engines.  There seems to be one strengthening rib at the 6 oclock position on these rods, which, compared to these late sandcast, very early diecast rod, does not have this rib.  So I guess Im asking if there are early and later rods between sandcasts and pre-17000 diecasts?  Service bulletin mentions the stronger version of the rods was introduced c. 17000evin.

The second part of my conundrum is the issue of the grub screws present in the crankshafts, near the small end journals.  I can see Mark B's early crank has the grub screws then these went to a flat blade screw head somewhere in the early diecasts.  Then of course these were replaced by peened over balls later in CB750 production.  Has anyone noted these differences?

Thanks!