Topic: Strange engine numbers?

[Mycall1983]

My family have multiple 750 fours and parts, two of the engines have strange engine numbers. One is 750-2065*** (no CB in front) and the other is simply 075127P. We are located in Australia but it still doesn’t make sense to me?

Both are SOHC K models are far as I know.

[Nurse Julie]

Can you post a photo of the numbers and the bikes so we can see if they are original Honda Font and are K model CB SOHC 4'S.

[Mycall1983]

First one

[Mycall1983]

And second

[PeWe]

Replacement cases?

[Nurse Julie]

As PeWe says, probably replacement cases as not Honda Font.

[bryanj]

First one might be a police or official stamp on un numbered new cases, second looks like a dealer with no letter stamps.
New cases came unstamped, same as new parts frames

[Mycall1983]

Very interesting, very helpful and insightful 🤘🏻

[newday777]

I agree that they are most likely replaced cases that someone hand stamped. Unless you find the person/shop that did the change, you may never know the history of them. Many cases were replaced because of a busted drive chain that put a hole in the original cases.
Notice the uneven line of numbers. Factory stamping were done in straight line, probably with a type set to hold the numbers and letters straight.

[CycleRanger]

And second

As others mentioned, very likely a replacement case that was assembled by a dealer or a shop that only had number stamps.

[seanbarney41]

Agree that they have been re-stamped, probably replacement cases.  We can tell you they are not early K0(sandcasts) by the raised rectangle around the number pad.  There may be other visual cues which can narrow down roughly when these engines may have been made.  Some more good pictures may get us started.

[ZTatZAU]

... Many cases were replaced because of a busted drive chain that put a hole in the original cases.
...

Quick question!  I've owned my K1 750 since 1971 and seem to recall a Honda "recall" that installed a protective shoe or guard of some sort to protect the cases in the event of a broken chain.

But when I recently resurrected the bike after a thirty year hiatus, I was surprised NOT to see any sort of a add-on chain guard around the final drive sprocket.

I know I replaced the final drive sprocket, rear wheel sprocket and chain at some point in the distant past but don't remember dealing with any "extra device" that I might have pitched.

Can anyone post a picture of the Honda chain guard device?  Or did I dream all this up?

ZT

[Don R]

  Sorry for the thread hijack,
 Somewhere I have a picture of an engine that I bought that had parts of the drive chain inside the engine case, it had gotten between the transmission gears, damaged them and was spit through the circular hole cover and hanging out the bottom of the engine.
 I'll try to get a pic of an interior chain guard today. I have 10 750's (some are parts or drag bikes) and I don't think any have the guard in place.
 I'll get a pic of a blank engine number pad also.
 

[Stev-o]

And second

Does the engine number match the frame VIN or title?

[Don R]

 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.

[bryanj]

Pic from CMSNL K2 parts list

[CycleRanger]

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.

[Nurse Julie]

Chain protector fitted from VIN:1026144 up to 1044805.

[Mycall1983]

Agree that they have been re-stamped, probably replacement cases.  We can tell you they are not early K0(sandcasts) by the raised rectangle around the number pad.  There may be other visual cues which can narrow down roughly when these engines may have been made.  Some more good pictures may get us started.

Yeah I’d say the dealer just copied the original numbers without the CB.

[Mycall1983]

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.

No idea the engines came as part of a mass purchase of parts.

[newday777]

... Many cases were replaced because of a busted drive chain that put a hole in the original cases.
...

Quick question!  I've owned my K1 750 since 1971 and seem to recall a Honda "recall" that installed a protective shoe or guard of some sort to protect the cases in the event of a broken chain.

But when I recently resurrected the bike after a thirty year hiatus, I was surprised NOT to see any sort of a add-on chain guard around the final drive sprocket.

I know I replaced the final drive sprocket, rear wheel sprocket and chain at some point in the distant past but don't remember dealing with any "extra device" that I might have pitched.

Can anyone post a picture of the Honda chain guard device?  Or did I dream all this up?

ZT

That was for the front sprocket area as bryanj and CycleRanger showed, not for the rear sprocket.

[Don R]

 It was a replacement empty case for a broken engine (probably by one of the legendary chain failures) bike. All of the original parts were saved and installed into it.
 I think the three-dot recall included a larger front sprocket, new chain and moving the battery drain so the acid didn't drip on the chain, on early bikes the #28 carburetor tops and 1 into 4 throttle cable got changed too. My #5511 sandcast got the three dots on the rear hub, apparently the tech didn't want to mark up the engine.
 I didn't find my chain guard yet. The 76 Hondamatic I parted out has a chain guard that goes on edge rather than flat. I would expect if to work better, it was very close to the center of the rollers and seems like it would be more likely to keep a chain from bunching up. It didn't fit in a 5-speed engine though.

[ZTatZAU]

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

[Don R]

 I think the three punch marks were a K0 thing, the chain issue and carb cables were corrected on new bikes so by the time the recall happened. I'm unsure when the case guard came and went. I don't think I have one on a bike here, but the guard I have has met a chain up close before.

[HondaMan]

... Many cases were replaced because of a busted drive chain that put a hole in the original cases.
...

Quick question!  I've owned my K1 750 since 1971 and seem to recall a Honda "recall" that installed a protective shoe or guard of some sort to protect the cases in the event of a broken chain.

But when I recently resurrected the bike after a thirty year hiatus, I was surprised NOT to see any sort of a add-on chain guard around the final drive sprocket.

I know I replaced the final drive sprocket, rear wheel sprocket and chain at some point in the distant past but don't remember dealing with any "extra device" that I might have pitched.

Can anyone post a picture of the Honda chain guard device?  Or did I dream all this up?

ZT

I've got one (maybe more?), it was removed from an early K1 engine. It limits your sprocket choice to 17T or 16T, you can't fit the later-used 18T front sprocket in it. PM me if interested.