KR Heads

Racing K Models

Re: KR Heads

Postby wz507 » Sun Jun 10, 2018 12:47 pm

starcain wrote:More Pics

Regarding the -60R #6 head Starcain showed with the unusual combustion chamber modification, I believe “55panman” called it correct here…..

http://www.harleykmodel.com/phpBB3/viewtopic.php?f=5&t=517&hilit=starcain&start=20#p3377

….. when he suggested that it is a modification motivated by the -69R head design, but for an engine with a flattop piston.

The trough across the head is essentially the same as a -69R head, but in this case, because it was for a flat top piston engine it has to terminate in a flat surface over the piston to provide squish. Although we don’t know what piston the fellow was using, it is possible that he may have had a near neutral deck, i.e., slight pop-up or no pop-up whatsoever, in which case milling the head gasket surface was required to obtain a reasonable squish band clearance. I believe the radiused squish band shape was done to simultaneously preserve as much squish area as possible while allowing adequate airflow to the cylinder.
Starcain -60R modified head.jpg
Starcain -60R modified head.jpg (43.11 KiB) Viewed 238 times

We’ll never know the fellow’s true motivation for the modification, but everything appears to fall closely in line with the observations of 55panman. In querying other vintage racers, several have seen this design, suggesting this is not a one-off, but something that was attempted by other privateers too - likely post 1969.
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Re: KR Heads

Postby Mutt » Sun Jun 10, 2018 1:56 pm

The Circle E hallmark (Eck Industries) is from a foundry that Harley started using as early as October 1958. It may have been earlier, but I have a transmission case with such date code. That may give some kinda clue also
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Re: KR Heads

Postby wz507 » Sun Jun 10, 2018 2:20 pm

Mutt wrote:The Circle E hallmark (Eck Industries) is from a foundry that Harley started using as early as October 1958. It may have been earlier, but I have a transmission case with such date code. That may give some kinda clue also

Thanks for the input, as I had no idea what the circle E hallmark represented. Regarding when Harley found their way to Eck Industries, was at least as early as some of the K model consumer bike production because many of them had circle E head castings. I can't put a date on it other than to say the earliest heads didn't have the circle E casting and the later ones did.
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