Several weeks back I was attending a flat track race with a friend and he introduced me to several of his friends. As we were departing the race track walking back to our bikes, I over-heard a fellow utter the words “KR” something or another whereupon I inquired if he had a KR or any KR parts. He informed that he might be able to build a KR someday but was short several parts for his bike. But……… he just happened to have an NOS set of KR heads in factory boxes but couldn’t remember which specific heads they were, but volunteered to text me images of them. I awoke the next morning to the most unbelievable text images – his NOS KR heads just happened to be the rarest of rare – the 69R #8 for domed pistons. I inquired if by some remote possibility he would lend them to me to document and cast the combustion chambers and he simply said “if you are a friend of my friend you are welcome to take them”. I beat a hasty path to his house, retrieved the heads, thanked him profusely and returned home for casting and picture taking. Below are the images of the -69R heads and some comparative photos with the -52R heads. As always I wish it was easier to convey the 3D nuances in a 2D picture, but alas….
Aside from the obvious differences between the -52R and -69R heads, due to the flat top piston in the -52R and the domed piston in the -69R, there were a few other features that stood out.
• The -69 combustion chamber is fully sanded and blended whereas the -52 was employed as-cast.
• On the -69R head the circumferential clearance between valve head and side of combustion chamber has more top to bottom arc than the -52R head.
When you feel with your fingers it is a smooth radiused trough that you can easily fit your fingertips into.
The -69 heads and their respective boxes.
- LR -69 heads and boxes.jpg (115.94 KiB) Viewed 16838 times
Top view of -69R heads showing short window, fins fully encircling spark plug hole, the casting numbers between fins, and the #8 stamped on the lower edge of the heads.
- LR-69R top view.jpg (88.93 KiB) Viewed 16838 times
-69R casting numbers
- LR -69R casting numbers.jpg (196.22 KiB) Viewed 16838 times