What year is my cb72 project?

sarolea · Post by **sarolea** » Fri Sep 10, 2010 7:05 am

I'll probably also create a post in the restoration forum, but would like to find out a bit more about my bike first.

I'm pretty sure it's a cb72, since that's what the frame number begins with. The rest leaves me a little clueless. A quick googlesearch didn't immediately reveal a list of serial numbers for these bikes. A search on this forum learned me you can find info on the wiring harness, but what i think once was that label does not show any info at all anymore.

And what to me looks like a logical spot for the enginenumber (on the enginecasings in the rectangle, above where it has the oil-info) simply is hatched but perhaps the number is elsewhere? Engine is kinda dirty so it's hard to find a number if you don't know where to clean...
The lid that covers the points on the cilinderhead has type I on it.

Frame number is only five digits; CB72 - 111xx

Bike seems to be mostly complete, the only big part i noticed missing is the seat.

Thanks for your help.

jensen · Post by **jensen** » Fri Sep 10, 2010 8:14 am

Hi,

Welcome to the forum.

5 digits, starting with 111 is 1961, so it's an early CB72.
Do you have pictures of the engine ?

btw, were are you located ?
Belgium ? Netherlands ?

Jensen

sarolea · Post by **sarolea** » Fri Sep 10, 2010 10:14 am

Thanks for the reply; 1961 is the first year of production, right?
Which numbers did the first production bikes have?

Here is a picture of the engine:

Where should the engine number normally be located? I started disassembling it, but I guess that part of the story needs another topic

As far as my location goes, i guess sarolea gave it away. I'm belgian...

jensen · Post by **jensen** » Fri Sep 10, 2010 12:19 pm

Hi,

Yes, first year of production indeed.
Does it have 10 mm spark plugs ?

And yes, it's a 1961 engine, as the tower breather at the rear side of the engine is there.

Engine number should be located close to the clutch cover (on the left side of the crankcase).

Jensen

sarolea · Post by **sarolea** » Fri Sep 10, 2010 2:34 pm

I got curious, so I went back out after reading this.
There is not a lot of light around the bench where I have the engine on, so quality of the picture is only soso, but should be good enough to make sure I'm looking in the right spot.
I would expect a number in the rectangle the arrow is pointing at, but that is filled with a grid of little dots?

As far as the spark plugs go; is the 10mm referring to the diameter of the threaded shaft that screws into the cilinderhead? I didn't have a caliper at hand (will check tomorrow) but at first sight the diameter is very small so 10mm or perhaps even a little less.

And then i just realised google might know the answer too; spark plug is an NGK C-7HS, so yes: 10mm.

davomoto · Post by **davomoto** » Fri Sep 10, 2010 4:29 pm

Yes, that's where the serial # should be. Clean it really well, and if there's still no sign of a number, you have a replacement top case.

sarolea · Post by **sarolea** » Mon Sep 13, 2010 9:17 am

Scrubbed the zone around the number and no serial to be found. Took a better picture too.

Apparently that means i have a replacement case? But since it has the tower breather on top it must have run into trouble early in its life? How long was this type around?

I read around a bit more on this site and learned (amongst other things) that the instrumentpanel on my bike is 61 only so that seems to be correct.

Does my serial number put me early or late in 61?