a41capt
Well-Known Member
The Harley Davidson KR engine (45 cubic inch racing engine from 1959 to 1969) was of a side valve configuration with only a 6:1 compression ratio. However, it was very competitive until the overhead valved British motorcycles hit the racing scene, causing the AMA to limit the total displacement of the British bikes.
I raced both a KR and a BSA Lightning 650 on the dirt track in the late 60s early 1970, and I felt the overhead valve higher compression engine (9:1) outperformed the side valve flatheads hands down, even with the 100cc difference.
John W
I raced both a KR and a BSA Lightning 650 on the dirt track in the late 60s early 1970, and I felt the overhead valve higher compression engine (9:1) outperformed the side valve flatheads hands down, even with the 100cc difference.
John W
