Valvetrain Components
About Valvetrain Components
The valvetrain is the chain of parts that opens and closes the engine's valves: the camshaft, tappets or lifters, pushrods on overhead-valve engines, rocker arms, the valves themselves, and the springs and guides that control them. Wear shows up as ticking, lost power or poor running, and riders also upgrade the set to change how the engine makes power.
The sub-categories follow the path of motion. Camshafts set when and how far the valves open. Tappets & Lifters ride on the cam, and Push Rods carry the motion up to the Rocker Arms & Parts. Engine Valves open and close the ports, and Valve Guides, Springs & Parts keep them centered and closed.
Choose parts as a system, not one by one. A camshaft with more lift or duration needs springs that can handle it, and may need different pushrod lengths or lifters, so follow the cam maker's parts list. Check the engine family and year range, such as Harley-Davidson Twin Cam, M8 or Sportster, or a dirt bike model such as a KX or RMZ. Pick your machine in the Ride Finder at the top of the page.
Brands in this category include Andrews, S&S Cycle, Prox, Wiseco and Feuling Parts. The wider group is Engines & Engine Parts.
FAQs on motorcycle valvetrain parts
Which valvetrain parts should I replace together?
Parts that wear against each other are best changed together, such as a camshaft with its lifters, and valves with their guides and springs. Your service manual and the part maker will say which parts to renew as a set.
Why do valve springs matter when I fit a new camshaft?
A cam with more lift can push a stock spring past its limit, which can cause valve float or damage. Use springs rated for the new lift, and check clearances as the cam maker instructs.
What is valve clearance?
Valve clearance is the small gap in the valve train when the valve is closed, set with shims or adjusters on many engines. It is checked at intervals given in the manual, because wrong clearance affects running and valve life.
Do I have to remove the cylinder head to work on the valvetrain?
It depends on the engine. Some parts, such as pushrods and rocker arms on many overhead-valve engines, can be reached with the head on. Valves, guides and springs usually need the head off. Check your manual.
Can I mix parts from different brands?
Often, but only if the specifications match, such as lift, spring rate and pushrod length. Mixing parts that were not designed together can cause clearance problems or wear, so read each listing's notes and the cam maker's parts list.
