Matching numbers ?

[the lodger_imp]

I have an interest in classic bikes , where there is an obsession with matching engine and frame numbers. If they match it indicates that the bike left the manufacturer with its original engine in the frame. Depending on manufacturer , these numbers aren't necessarily the same but would be in the correct ballpark eg for 1970's Kawasaki triples the numbers should be within 400 of each other ( It's a bit more complicated than that but you get the point ).

I am imagining the CB1100 as a classic bike at some point in the distant future and the discussion is around what constitutes matching numbers.

So I am looking at my CB1100A-D engine and VIN ( frame ) numbers I am pretty certain the engine and frame are "matching" in that I would be very surprised if the engine has been replaced.The last three numbers of the engine and VIN are 875 engine and 869 VIN ; a difference of 6 which seems very close to me and therefore matching in my book for a CB1100

Is this typical ? How close are your numbers if you want to share.

[Cormanus]

A very few members included their engine numbers in their registry entry and I've included them in the spreadsheet. It can be found here: https://docs.google.com/spreadsheets/d/1...=454524829

At a quick glance there seems a bit of a discrepancy between VIN and engine numbers on some of the US bikes.

[the lodger_imp]

Cormanus

Thanks for the spreadsheet. I would agree based on the small sample noted there is no correlation between engine and VIN numbers and the closeness of mine is pure coincidence.

I guess this means that engines are given their numbers before being put in a frame or a frame is given its VIN with no reference to the engine already in it .

Shame that they don't match but not really surprising in retrospect. I wonder when matching went out of fashion , presumably driven by production line pressures.

Cheers

[Cormanus]

I think it's really interesting given the apparent need for regulators to monitor VINs as a guard against what they call re-birthing. I'm not sure that I can see why engine and frame numbers aren't identical and there's not a requirement to fix a compliance plate if they change. On the other hand, fitting new engines is not all that unusual in the life of a vehicle, so maybe the real key is in the earlier digits—SC65 etc.

I must look at my engine number and see how it relates to the VIN.

[LongRanger_imp]

It certainly wouldn't be practical for those manufacturers who outsource their engines from third parties. And otherwise, I would expect most manufacturers to have separate engine lines. They produce a batch of engines, track and number them through the assembly process, and then marry them up to a batch of chassis assemblies later.

[flynrider]

I contracted with Honda's manufacturing software group back in the mid 90s. Back then there was no connection between engine numbers and VINs. Engine numbers were assigneded at the time of engine manufacture, while VINs were based on assembly line setup and sequence.

[GoldOxide_imp]

Sounds sensible to me.