Engine case numbers match VIN

[socalpig]

I was reading some posts about VINs. In one of them I saw a statement, that may be a quote from a book, that said "if the belly numbers match the VIN then something is wrong." I have a 1960 FL and they do match. In 1960 FLs started with VIN 60FL2001. Just to put numbers out there we will say my VIN is 60FL2111. It is not. That would make it the 1110th motorcycle built that year. The factory could have been using up all the motors from the 1959 model year. That explains why you could have 1959 case numbers on a 1960. If the engine shop was just starting to stamp cases with the 1960 model year production. And starting to make 160- cases for big twins. Then the motors are assembled and taken to the line for installation in a frame. In what is a random order. With that, and the fact that they built multiple models at the same time, in mind. And production numbers ran in sequence. Both for the engine and VIN. Why could the 1110th engine produced that year, or any engine that year, absolutely not meet up with the 1110th bike, or its counter part?

[socalpig]

nobody has anything to add?

[RUBONE]

Because belly numbers and VIN numbers are applied at different points in the production cycle and at different times based on production demand it is a near impossibility for the numbers to match. However if the number is modified it is very likely that they could! Without pictures of the numbers in question I doubt you will get much response. JMHO
Robbie

[john HD]

so cal

photos would help.

john

[FlatHeadSix]

it is a near impossibility for the numbers to match
Robbie

But, there is a chance that they could have. I have a 5 different Lightweights (Hummers) sitting in my shop right now and all of them have belly numbers and VINs that are very close. I would bet that there was more than one that left the factory with matching numbers. I'll take some pictures and post them in the morning.

But (there's always a big but) that is strictly for the lightweights, they made a lot more big twins and 45's so the time delay between the machine shop where the engine cases got the belly number and the assembly line where they got the VIN was probably a lot higher and the chance of matching numbers was proportionally higher as well. As Robbie said; nearly impossible, but it could have happened.

pictures tomorrow

mike

[Speeding Big Twin]

socalpig, I was wondering what the outcome was regarding your numbers. In my photo collection I have several examples which appear factory-stamped where the sequential portions of the serial number and belly numbers are close to each other:

1. 40ULH, difference of one
2. 41EL, difference of one
3. 42U, difference of three
4. 56ST, difference of five
5. 40G, difference of six

And I have nine other examples with a difference of no more than 21.

The only reason I can think of for sequential portions never to match each other would be if a directive was given to prevent such a thing. But I can’t see any reason for such a directive. Therefore I have to conclude that the sequential portions of serial numbers and belly numbers could match each other on rare occasions.

Your engine could be one of those rare items provided of course all your numbers are factory-stamped. But the only way we’ll know is if you post photos of your serial number and belly numbers. I understand your security concerns but you can easily black out or cover some of the characters. Eric