Warrantied Blank Engine Case or Tampered?

I've read some threads on here regarding this situation but I wanted to post my pics to get the thoughts of the forum. I have a Z1 900 engine with no engine number where it should be. The surface is machined smooth and when you run your finger over it you don't feel anything. I've read that engines replaced at the dealership are blank. I've also read that there might be a lip around the area where the number is stamped. Mine does not have this lip. But I also have another Z1900 engine that has a number but no lip. I know people remove numbers if they're stolen but I'm not sure what I have here. Could anyone look at my pics and let me know what you think? The picture with the number is the engine with no lip.

The early crankcases did not have a lip on the boss for the frame number to be stamped, that was added later to help prevent tampering. Your first picture looks to be an early example. Your second picture looks like a later model crankcase(oil capacity script) that the number has been sanded off. It should have a lip, and the surface should appear to be "as cast" not smooth.

JMO, Mike

Early cases with short number pad has no lip.
Later cases with longer number pad had a lip.
Pic with short pad and numbers is correct.
Pic with long pad has had numbers and lip removed.

Okay, thank you guys for the input. What is the protocol for something like this? Can I throw it away or am I supposed to call law enforcement?

The engine number is not recorded on the Title, at least not in Nebraska. At one time there was a "paper trail", recording which VIN. was married to which engine number, I don't know if that still exists? I'm trying to find some information for another member of the forum on a 76/77 model KZ900 and the records for that time frame seem to be marginal at best. Even if there was a legal issue for a registered vehicle I would think the cases could be used on something untitled like a race bike. It would be interesting to know when and why the number was ground off, but I think it would be impossible to find out. I owned an H2 that apparently had replacement cases, no number, but it was obvious nothing had been removed, the dealer simply didn't restamp the number. There are a few handstamped engine numbers from the Lincoln factory done by your's truly. I tried to get them straight but I'm sure they weren't all perfect, someday it would be cool to see one I stamped/built!

Just my .02 Mike

I certainly wouldn't throw them away that would be such a waste.
Someone will be desperate for a decent set of cases for their race bike or to replace their damaged cases etc and they will sell.
Stick them on Ebay for $1 starting bid and sit back..

I'm here in CA and from what I understand you must have an engine number or your bike can be confiscated. I've never dealt with freight shipping on eBay but I'll look into it. Thanks again.

Are they on a bike or just spare cases ?
Here in the UK we have the frame and engine numbers listed on the bikes ID papers ( V5c log book )
If i had a bike with no eng numbers on the cases i'd just stamp them on to match the book and leave it at that or if you had a terminally damaged set of cases you could use the numbers off those and destroy the originals.
At the end of the day it's only a set of old bike cases.. Not murder..

They're spare cases. I won a mini storage auction lot full of old Kawasaki parts and these two engines were in there . Huge lot of Triples stuff. I have a buyer who is interested in my numbered Z1 900 and I've got him interested in the "blank" case and I'm hoping to sell it to him for cheap or even give it to him. I will let him know what his options are in terms of trashing it, giving it to a drag guy, or re-stamping it if he's wants to skirt the law. I know these are classic bikes and every case counts but I don't want any legal trouble from trying to sell something so small.