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Serial Number Mystery

Jeff Fortenbery

Jeff Fortenbery

Just got it firing!
GT Contributor
Joined
Aug 17, 2017
Messages
21
Location
Ohio
I recently purchased what I thought (and the title states) is a 1978 850 T3. It's ROUGH ... to say the least. Not quite a roller, as the rear wheel and the rear drive weren't attached to the frame. Engine mounted in the frame, but locked up. Oh yeah, did I mention - no transmission?

At any rate, I've started researching to see what it is (or was) and the serial number doesn't seem to match anything I can find on this site or elsewhere.

I'll add a picture (or two) if I can figure out how, but until then, the tag on the headtube says, "Mar 1977"
for Model, it says, "1978". At the bottom, it says, "Eng 104437". That does, indeed, match the engine number. The stamped numbers on the headtube say, "DGM OM" with a large space between the two series of letters - and no numbers.

Can any one point in the right direction?

Thanks in advance,
Jeff

2012 Norge 8V (rollerized)
1978 850 T3 w/ floorboards (maybe)

IMG 2563
 
Here is what I can tell you. In that time frame, VIN was not used. Only the engine serial number which was also stamped on the frame ID plate. The information on the plate is what the bike is as the engine number matches. So it is a 1978 model year produced in March of 1977 just like the plate says. In normal convention the model year change would usually be later in 1977 (usually June), but the Italians do things their own way.
 
Thanks, John. All of the internet resources seemed to indicate VINs (as far back as 1955) that consisted of letters and a 5 digit number. That's what threw me for such a loop.

The engine is an 850 small valve with Nigasil cyls, so that holds up. It has 3 discs with proportional braking. Funny, though, that it has running boards...

IMG 2509
 
As I became a little more "educated", i've learned the cyls are actually chrome.
I'm replacing with new Nikasil 88mm cylinders.
 
If you're going "big bore" with 88 mm pistons, then I'd recommend having the crank balanced or at the very least making sure piston assembly weights are the same.
 
Thankks, Charlie!
It's at the machine shop right now having crank balanced and valve seats ground. I appreciate all the help I can get. It's been a while since i've rebuilt an engine, and this is the first 4 cycle motorcycle engine for me...
 
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