Identify the cylinder contest

Here is a link to a cylinder. I would like to hear from our experts on what vintage they think it is and whatever else that they may know. Hopefully the answer will surprise a few people.

Follow the link and look under Knuckle cylinder.

http://new.photos.yahoo.com/hd36ohv Thanks Jerry

Looks like a rear cylinder from a 36 knuck. What am I missing?

It appears to be a 4 fin 1936-1939 61" OHV cylinder.

I am going to let this go for a few days and see what happens. Kyle, you know the answer if you just think about because you and I have talked about it.

Jerry

Perhaps if we had more than one dark photo we could make out what it is. It does carry the part number of a 1936-1939 61" OHV cylinder.

Chris I apologize for my poor photos but I am a tractor/motorcycle mechanic and not a photographer.

OK - more about the cylinder. If you are an astute knucklehead kinda guy and see this photo you will come to the same conclusion that Chris came to - 4 fins = 36 to 39. If you even more knowledgeable you will recognize this as a 1936/37 cylinder by the raised casting numbers. Somewhere around the 1937/38 split they changed the casting numbers to recessed - I have never been able to determine when.

Now - would anybody believe that this cylinder was actually made much later than that - 1944 to be exact - June of 1944. If you do not believe me go back to original post and follow the link now and see the second shot of this cylinder with its' 6-4 casting date. This is the original rear cylinder on my 1944 E knucklehead. My 1943 E has the same rear cylinder only with a 10-2 casting date. Ronnie Cox's 44 E has the same situation.

Here is the only explanation that I can come up with. All 3 of these bikes have a late 39 casting date on the front cylinder so I surmise that they must have had a bunch of fronts in warehouse and made a rear to match but somehow used the earliest casting mold that they had.

I would love to hear anything anybody has to say about this.

Jerry

Jerry,
Nice info thanks for sharing.

About the recessed / raised casting numbers on cylinders, I have seen an untouched 38 EL export bike in the 3000 serial number range that still had the raised numbers. Hope this helps.
Eric

I took a look at a pair of cylinders I have for my 38, with raised part #'s and the casting dates are 12-31 and 10-7. Did they use a week-day system?

I have looked at a few dozen Knuck cylinders in the past few days. It appears the later 5 fin cylinders have a full date code on them. A raised letter fot the month and the tag with the day and year on it. All of the 4 fin cylinders I found had a code system I haven't figured out yet. Things like 41 9. Anybody have a clue to this earlier date code system?