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Hopefully this thread will sort out some of the inconsistencies that I have seen with 1941 FL cylinders. However it will probably be as clear as the early 1941 frame situation which is blurry at best.
From my experience and observation of original 1941 FL motorcycles they had a cylinder that was a little different than later knucklehead FL's. In general they had a thin base mounting flange like the early EL had of approximately 1/2" (.500") with absolutely no markings on the base flange itself but had a casting date up on the side of the barrel that usually got machined mostly away to achieve clearance for mounting bolts. These first 3 photos support this.
The third photo is one of few where you can actually recognize part of the casting date and the last digit is unmistakably a 1 hence 1941. So far everything seems to be going to plan but this 4th photo possibly throws a wrench into logic. It has a J-25-0 casting date which should translate into October or November 25th of 1940. It has all the typical base flange stuff (MC logo and casting date plus it has the later 9/16" (.562") thick base flange). Theoretically this cylinder should predate the first 3 yet it has the characteristics of later cylinders. The only explanation I can come up with is that this is a late manufacture cylinder made in 1950 which is plausible because the newest knuckles are only slightly more than 3 years old and I think HD would have made these cylinders as demand dictated.
This last cylinder fits no rhyme nor reason as far as I am concerned. It is a 1946 FL barrel with all the typical markings which for some reason has reverted back to the 1/2" thick base flange which is a very obvious step backward.
These cylinders are all standard deck height and show no obvious signs of alteration. All answers and speculation is welcome.
Jerry
From my experience and observation of original 1941 FL motorcycles they had a cylinder that was a little different than later knucklehead FL's. In general they had a thin base mounting flange like the early EL had of approximately 1/2" (.500") with absolutely no markings on the base flange itself but had a casting date up on the side of the barrel that usually got machined mostly away to achieve clearance for mounting bolts. These first 3 photos support this.
The third photo is one of few where you can actually recognize part of the casting date and the last digit is unmistakably a 1 hence 1941. So far everything seems to be going to plan but this 4th photo possibly throws a wrench into logic. It has a J-25-0 casting date which should translate into October or November 25th of 1940. It has all the typical base flange stuff (MC logo and casting date plus it has the later 9/16" (.562") thick base flange). Theoretically this cylinder should predate the first 3 yet it has the characteristics of later cylinders. The only explanation I can come up with is that this is a late manufacture cylinder made in 1950 which is plausible because the newest knuckles are only slightly more than 3 years old and I think HD would have made these cylinders as demand dictated.
This last cylinder fits no rhyme nor reason as far as I am concerned. It is a 1946 FL barrel with all the typical markings which for some reason has reverted back to the 1/2" thick base flange which is a very obvious step backward.
These cylinders are all standard deck height and show no obvious signs of alteration. All answers and speculation is welcome.
Jerry
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