Here is a no stamp newer replacement engine case removed from a sandcast bike. It has the Sandcast's cylinder and head. It didn't get numbers but did get the three punches from the factory recall that addressed the chain breakage.
Thanks Don! I had never heard about the three dots before. There are no dots punched on my K1, so I guess that means... no chain guard recall was ever accomplished. Does that sound right?
Pic from CMSNL K2 parts list
Pic from CMSNL K2 parts list
This is the "case saver" part pictured there.
Imho, it's of dubious utility and I believe it was just a stop-gap until Honda made changes to the sprocket/chain.
Appreciate the pix guys! The guard is just what I had pictured and expected to find under my ("final drive") sprocket cover.
Chain protector fitted from VIN:1026144 up to 1044805.
What happened with 750s after vin 1044805? My vin is 1072186. Did a new redesigned chain and sprocket, or other improvements, eliminate the need for the add-on guard?
ZT
Boy, that's a loaded question!
Here's the largely hidden factory changes in the 750K1 comprising the 11/70 "silent update", which corresponded with the intro of the new chain:
1. 17T countersprocket, 100-link chain.
2. new Diamond XL-style chain, made by RK of Japan.
3. steel countersprocket chain guard (also available free for earlier bikes, along with RK chain if being officially 'recalled', required new chain also).
4. swingarm bushings changed from the early zamac plastic to phenolic (didn't self-crumble if ungreased) to preserve rear-wheel alignment in frame under power.
5. longer drain hose for battery's overflow port, and instructions for re-routing it (DonR noted above).
6. for earlier bikes that put racing stripes down the back left shoulder of their jacket, an extended chain guard.
Inside the engine, the clutch also 'lost' the 2 wires that held the back 2 steel plates toward the rear of the hub, to reduce their tendency to stick. It was at this time that an 'unofficial' memo was circulated about putting in some oiling holes in the inner clutch hub (sandcasts lacked these, as did many K0 and some early K1) if there weren't any. This was said to reduce the "suddenness of the clutch engagement" and to "extend the life of the clutch friction plates" in those almost-oilless wet clutches. We also enlarged the oil feed hole in the right end of the mainshaft (inside the clutch hub) to add some more oil to the clutch. (I mentioned some of this in that sandcast rebuild I did 2 years ago).
