K or KR?

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K or KR?

Postby Arvid Solli » Mon Apr 12, 2021 5:42 pm

Hello, and greetings from Sweden. I have bought a 52 K model in bits and pieces. Engine was assembled when I got it. After tearing the top end, and doing some googling, I discovered that it is in fact equipped with KR cylinders....!
Prior to this project, I have been riding Sportsters and knew very little about the K. The fact that it didnt have clamp on, but stick-in 1 3/4" exhausts made the picture clear. 030 bore and looking really nice inside, no need for a rebore. Valves are 1,800 & 1,615. Cams was mix and match, with what I believe to be KHK exhausts due to narrow sprockets. The intakes, however, was totally stock WLA ones.
The bottom end has me wondering- what is this? All pressed shafts exept the nut on the crankpin left side. Both flywheels have the same numbers: first three ones hard to read, BC8/868?, then 23932-52 , encirkled "u" 2. On the outer rim on both flywheels is a small, less than a 1/4", bar & shield type stamp with the letter "HD" and an "8" underneath.
Rods are 24292-52 & 24296-52.
Any suggestions as to what I got would be nice!
Arvid Solli, way up north in Sweden
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Re: K or KR?

Postby wz507 » Mon Apr 12, 2021 6:22 pm

Hi Arvid,

You’ve got an interesting potpourri of history there. The flywheels you describe are ’52-53 K Model 3-13/16” stroke steel wheels that, with the exception of the one crankpin nut you mentioned, are pressed together.

Are the cases by any chance baffled at the top just beneath the cylinder?

With the KR cylinders, I’m curious to know what you’ve got up top for cylinder heads. Please post some pictures of the combustion chamber and head castings if you can. Thanks.
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Re: K or KR?

Postby panic » Mon Apr 12, 2021 6:32 pm

If I don't say anything, am I still wrong?
Last edited by panic on Tue Apr 13, 2021 10:31 am, edited 1 time in total.
[url="http://victorylibrary.com/L-BK.htm"]The Linkert Book[/url]
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Re: K or KR?

Postby Arvid Solli » Mon Apr 12, 2021 7:11 pm

Heads are std K, nothing fancy there. I know the intake cams are WLA by comparing them with a set from my shelf, also they are a straight grind. I will buy a full set of KHK profile lobes from mr. Argetzinger at Enfield racing and put the original narrow sprocket ones aside. As for the cylinder casting numbers, yes, I was thinking there should be an "R" in the end. But how can one otherwise explain 1 3/4" internal exhaust ports?
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Re: K or KR?

Postby 55panman » Mon Apr 12, 2021 7:30 pm

The early, (first 2?) years KR cylinders did not have R's cast in their casting identification number on the base flange. Maybe to assist AMA's homologation acceptance of the KR as a factory street bike for class C racing. I have a couple of pairs like that and they are definitely KR as they are push in exhaust, KR valve seats, and the intake port below the valve seat is for sure a KR shape, entirely different from a K. Ron
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Re: K or KR?

Postby Arvid Solli » Mon Apr 12, 2021 7:41 pm

Have been trying to upload some pictures, but to no luck. Anyone know if 52-53 KR shared crankcase with the K? Mine has threads for the tin transmission cover.
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Re: K or KR?

Postby JerrryR » Mon Apr 12, 2021 7:49 pm

If you can't upload the pictures Arvid email them to me and I'll post them for you. [email protected]
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Re: K or KR?

Postby 55panman » Mon Apr 12, 2021 10:00 pm

Arvid, I think they shared the same basic casting but maybe different cores. There was metal on the primary side to drill and tap the primary screws, so probably someone did that to put a tin primary on. R
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Re: K or KR?

Postby JerrryR » Mon Apr 12, 2021 10:20 pm

Arvid's pictures over the next two posts.

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20210226_105551.jpg (309.03 KiB) Viewed 8403 times


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20210328_001342.jpg (141.84 KiB) Viewed 8403 times
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Re: K or KR?

Postby JerrryR » Mon Apr 12, 2021 10:22 pm

Arvid's picture.

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20210409_075638.jpg (424.74 KiB) Viewed 8403 times
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