C72 Help Required

[jensen]

Hi G-man,

engine and frame numbers of the C72 dreams from 1960 until 1962 :

1960 :

engine numbers : from C72E 010001 to C72 E 034082
frame numbers : from C72 10001 to C72 34082

(six digits for the engine numbers and 5 digits for the frame numbers, I have one upper engine case, sand cast, with number 012034, the crank bearings are different then the 1961 version by diameter, breather is different then later ones)

1961 :

engine numbers : from C72E 1100001 to C72E 1143976
frame numbers : from C72 100001 to C72 143960

(seven digits for the engine numbers and six digits for the frame numbers, I putted in some pictures of this engine, including a view of the breather. This is different than a 1961 CB72 engine case which has six digits, see picture, and notice the strange reworked engine breather)

1962 :

engine numbers : from C72E 2100001 to C72E 2107263
frame numbers : from C72 260001 to C72 262238

(also seven digits for the engine numbers and six digits for the frame numbers, see the picture of the engine case number, the last digit is a zero, a bit difficult to see)

This is unlike the C77 engines, witch had the standard six digit numbers (see image of this 1962 C77E engine case. The numbering of the C77's where more according to the standard (cb72 / CB77 numbering)

That means you have a 1962 engine, everything with C72E is called domestic by the Americans, because in the US the engine numbers start with CA72E...... The A stands for American, these engines do have some different gears to make it more comfortable at the speeds in the US.

When you take a close look to the numbers, you will see that there are more engine cases made then frames.

The head cover is clean, with no marks on it like type 1 or 2 engine, the top engine doesn't have a breather tube, the left crankcase cover has the small oil filter cap and the crank bearing diameters are comparable with the later engines. Some bolts are JIS, be careful with them, as the are quite difficult to get. There are over 12 different left crankcase covers for these type of engines, could you post a picture of this cover, especially the way the oil pipe (outside of the cover) is shaped ?

The winker lights at the rear are not integrated in the shock mounts, like the later ones, so that means that you have a early 1962 frame. The front winkers should be integrated in the plate steer, there where no exceptions. Please show us pictures of the front winkers (both sets), but I doubt that the antenna style winkers where original to this bike, but it could be, only if the bike is imported from Denmark or Sweden (maybe Norway too). Handle bar grips should be gray / creme, not black.

I'm unsure of the batches from the gas tank, I thought it should say dream, not dream 250, but I could be wrong here. I have a 1962 gas tank with the original dream batches on it, but maybe both types where used. If you need better gas tank panels the these, I have a view lying around, pitted, but not as bad as yours.

The mufflers should be the stainless types, on the picture it shows that the left muffler is nice and shiny (probably a stainless type), but a close up could change my opinion. These stainless mufflers where magnetic, just like the steel ones, you could only judge it by looking at it closely. If there is a little rust on these muffler, it still could be a stainless one, the stainless steel used in that time is from the same quality as the modern stainless steel. The resistance to oxidation goes below ST304, or other types of stainless steel (read more about stainless steel on : http://www.spiusa.com/Ref001/austenitic.html).

I think I have a right stainless muffler lying around, but I have to loo it up first to see the shape of it.

It's always good to have a second engine, if you run into trouble, I have five early C72 engines lying around, you know how to reach me.

Jensen

[G-Man]

Jensen

Many thanks for all of that information. It makes very interesting reading. I have almost two bikes. The one in the pictures above and a second one (minus frame). The strange winkers I mentioned are from the second one which has slightly later numbers. Eng C72E 2123692 Fr 215194 (not sure of the prefix as I no longer have the frame) Number is from the registration document.

The engine cover picture is from my spare engine. The complete bike is currently in storage away from home. I have attempted to do a close up of the cover from the pictures I have....

The muffler has survived much better than the chrome on the bike so I think that it is a stainless one. Yes the stainless was not a good grade but it seems to have survived. I think that I have access to a right hand muffler but if you have a good one that you are willing to part with I would be interested.

Regards

Graham

[G-Man]

Ed

I used to work with a guy who used to say " you learn something OLD every day "

Thanks for you help

G

[jensen]

Hi G-man,

Very, very interesting winkers. If you want to part from it....
Really, I have never seen these types but I knew they where existing in the country's I mentioned in my earlier post. The best thing is that you have a complete pair, and these winkers are in good shape. Are this Stanley winker glasses ?, or is it another brand ?

Jensen

[G-Man]

Jensen

Unfortunately one of the glasses is broken and only 1/2 is present so the pair is not complete. I would be happy to swap them for other C72 parts but you would have to get one replacement glass.

Not sure if there is a name on the glasses but they look just like the ones on the CMSNL C72 online parts manual. I have the rear ones too, but no glasses for them.

Did I read somewhere that some early hubs were magnesium? The wheels from my spare bike seemed quite light when I carried them.

Regards

Graham

[jensen]

Hi Graham,

If those are Stanley, I might have a suitable glass for you, can you make a close-up picture of the glass (top view and side view) ?

What kind of coil do you have attached to the frame ?
Is it a small white (crème) one, or a large brown / black one ?

I heard that some dreams head a magnesium rear hub, that's why I asked, I actually saw one, but that was some time ago. It is not clear to me if these are original Honda, or taken from a CB92. I know that there are some parts for racing the C's out there, but these parts are more dedicated to the earlier models like the C71 / C76.

I got a box of old books, booklets, manuals from Japan, about very early Japanese motorcycles, written in Japanese. Among those books there is a booklet of the early dreams (kind of very early manual / parts list) also in the Japanese language. I'm translating that booklet, and in there are some very strange parts I have never seen before. My Japanese is not flawless yet, and I encountered some difficulties in translating, in other words, it takes a lot of time. Among these pictures are race pipes for the dreams, but I guess these are unobtainable.

I searched in my part manuals, and looked at the CMSNL-site, but I can't find an exact picture or drawing of the front winkers. There is,. however, a sort of picture, but that are not the winkers you showed us. Can you point out to me where you found a picture of the front winkers ?

These stainless mufflers are prone to cracks and / or getting brittle over the years, especially around the points where the muffler is attached to the frame, in what condition is (are) yours ?

For some reason these stainless mufflers are made much lighter then the steel ones, I measured the thickness of a broken one and compared that with the steel one, but the thickness of the material is more or less the same. As the weight between stainless steel and ordinary steel is almost the same, I thinks it due to the fact that thee stainless mufflers don't have an inner tube, as the steel ones have, can you confirm that ? My stainless steel mufflers don't have a long inner tube, just a short one at the back to hold the diffuser pipe, and sometimes a short pipe to connect them to the exhaust pipe.

The same with the stainless mufflers for the CB72 CB77, these mufflers are much louder then the steel mufflers, including the older two piece steel mufflers. These early (stainless) C-mufflers are also louder then the later ones. I once tested the C77 on the dyno, but not with two different mufflers, so I can't compare both types .

Jensen

[G-Man]

Jensen

No sign of Stanley on the lens. Pictures are below, as requested. I have checked the CMS site again and you are right. The ones in the parts manual are not the same but are similar. The manual does not show the lever bracket incorporated.

My coil is black (metal can) with a green and silver foil label.

The hubs look strange because they look black rather than a normal oxidised aluminium colour.

G