Valve Guides, Springs & Parts
About Valve Guides, Springs & Parts
Valve springs close the valves after the cam releases them, guides keep each valve stem centered as it moves, and retainers, seals and shims hold the assembly together. Weak springs can cause valve float at high rpm, and worn guides let the valve wobble and can let oil past the stem.
Springs are listed by the lift they are made for, such as .550 or .625 inch, and the spring must handle at least the lift of your cam. Beehive springs are narrow at the top and are listed for Harley-Davidson M8 builds. Spring and valve kits bring parts together for models such as the Honda CRF250R and Kawasaki KX450F. Guides are listed by position, intake or exhaust, and by material, such as bronze or OEM style. Fitting guides normally needs head work by a machine shop. Shims are sized by diameter and thickness in millimeters, such as 10.00 or 9.48 x 2.75, and spring retainers are listed too.
Brands in this category include Moose Offroad, Prox, Feuling Parts, Jims and S&S Cycle. Pick your machine in the Ride Finder at the top of the page. Related categories are Engine Valves, Camshafts and Rocker Arms & Parts, all in Valvetrain Components.
FAQs on valve springs and guides
What is a beehive valve spring?
A beehive spring is shaped like a beehive, narrower at the top, which lets a lighter retainer be used. That reduces moving weight on the valve. It must match the valve, retainer and cam lift in your build.
How do I tell if valve springs are weak?
Measure the spring's free length and its pressure with a spring tester, and compare them with the figures in the service manual. Loss of power at high rpm can also point to weak springs, and a worn spring is cheap to replace.
Can I install valve guides at home?
Guides normally have to be pressed in and then finished to size, which needs the right tools and often a heated head. Most riders use a machine shop, and your manual describes the correct procedure.
How do I choose springs for a performance camshaft?
Use the spring the cam maker recommends, and check that it handles the cam's lift, with the right installed height and clearance. A spring that is too weak or too stiff can damage parts, so follow the cam maker's parts list.
Do I need new valve stem seals when I change valve guides?
Normally yes. Stem seals are disturbed when the valves come out and are cheap to replace, and a worn or hardened seal lets oil down the guide. Fit new ones and follow the service manual for installation and any special tools.
