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Hi all, new to the site and CX's, just bought a 1979 CX500C Custom with 55k miles on the clock for $100 that needs a triple bypass.

The cam chain was streeeeaaaached out, grinding up everything within it's throws. What a racket.

It's all apart and procuring parts now, thanks to the info on this site and the GL Global Forum I got up to speed quickly on the ins and outs of these fine bikes.



One question I have though, the engine number does not match the frame VIN number. They are close, but not the same.

Were these numbers matched (the same) from the factory when new, or is it normal for the frame / engine numbers to be different?



TIA,

Dave in Ohio
 

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Hi all, new to the site and CX's, just bought a 1979 CX500C Custom with 55k miles on the clock for $100 that needs a triple bypass.

The cam chain was streeeeaaaached out, grinding up everything within it's throws. What a racket.

It's all apart and procuring parts now, thanks to the info on this site and the GL Global Forum I got up to speed quickly on the ins and outs of these fine bikes.



One question I have though, the engine number does not match the frame VIN number. They are close, but not the same.

Were these numbers matched (the same) from the factory when new, or is it normal for the frame / engine numbers to be different?



TIA,

Dave in Ohio




Welcome, no they didn't match originally.
 

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Yep, neither of my bikes match, one of them is way off, but from the correct model year. *shrug* These engines are so close to identical I haven't worried!
 

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I'd bet that your '78 is the one with the numbers far apart. It's because there was a problem with the '78's (I can't recall what it was) that required dealer service. From what I understand, the dealer would swap out the engine and send the old one back to Honda to be retrofitted. There's three punchmarks on the engine next to the vin on motors that have been upgraded.
 

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I'd bet that your '78 is the one with the numbers far apart. It's because there was a problem with the '78's (I can't recall what it was) that required dealer service. From what I understand, the dealer would swap out the engine and send the old one back to Honda to be retrofitted. There's three punchmarks on the engine next to the vin on motors that have been upgraded.


Not that I've ever heard of, the camchain tensioner recall was done at the dealership. Only way they'd ever authorize and engine swap was if there was catastrophic failure.



The numbers on very early bikes in the model runs would sometimes match, there was a matching bike on Fleabay a few years ago that was the 3rd or 4th off the 1980 (I think it was 1981) production run. The reason they didn't all match was that if any issues were found by quality control on the assembly line, the engine would be pulled off line to address it, so that sequence number would be skipped. The earlier a bikes vin is, chances are the closer it is to the engine number.



If they did this, it's pretty clever, you don't need to look at long columns and reports to see how your quality control is going, all you'd have to look at is the disparity between engine and frame number, and you'd know very quickly if there was a problem with any one lot.
 

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So the dealer put the punch marks next to the vin when they replaced the cam chain tensioner?
 

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So the dealer put the punch marks next to the vin when they replaced the cam chain tensioner?


Right.



That is if they fit into the parameters of the bad serial numbers.
 

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Yep, I should remark that my '78 does have the three punches in a triangle, so that dealer service was performed. Makes sense about the assembly line quality control.
 
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