|Harley-Davidson Performance Guide
Cylinder Heads valves and springs
|Performance and Technical
information on cylinder heads, valves, valve sizes, valve springs, port size, port shapes
and compression ratios for Harley-Davidson motorcycles.
For most 80 CID engine applications, use of the stock intake (1.840") and exhaust (1.615") is recommended. Well designed engines with stock valves are capable of producing 100HP and 100 Ft.Lbs. of torque. The expected power band on an engine with stock valve sizes and 100 HP is from 4500 RPM to 6000 RPM.
Valve Spring Pressures and Installation Height
The valve springs installed should be the minimum seat pressure needed to maintain good valve contact. High seat pressures lead to rapid wear of the valve seat area.
Determining installed spring height