Camshafts
About Camshafts
The camshaft decides when each valve opens, how far and for how long, so it shapes how an engine pulls more than almost any other single part. Riders change cams to get more power or a different power curve, or to replace one that is worn or damaged.
Cam listings give lift and duration, a stage level such as Stage 1 or Stage 2, or a series name, and these set how aggressive the cam is. Harley-Davidson cams are matched to the engine family, such as Evolution, Twin Cam and M8, and to the drive, since chain drive and gear drive cams use different parts, so do not mix them. Cam kits and camchest kits are listed for some engines. Japanese bike cams are listed by model. A cam change often calls for matching valve springs, lifters and pushrods, and on a fuel-injected bike a tune, so follow the maker's instructions.
Brands in this category include S&S Cycle, Andrews, HardDrive, Jims and PSR. Pick your machine in the Ride Finder at the top of the page. To go with a new cam, see Tappets & Lifters, Push Rods, Valve Guides, Springs & Parts and Rocker Arms & Parts. The whole group is Valvetrain Components.
FAQs on motorcycle camshafts
What do cam lift and duration mean?
Lift is how far the cam opens the valve, and duration is how long it stays open. A cam with more of either usually moves peak power higher in the rev range, at the cost of low-speed manners.
Do I need a tune after a camshaft swap?
Often. A new cam changes how much air the engine breathes, so a fuel-injected bike may need a new map and a carbureted one new jetting. Check what the cam maker recommends for your model.
Will a bigger camshaft work with stock valve springs?
Only if the cam maker says so. A cam with more lift may need stronger springs and clearance checks, and the wrong spring can lead to valve float or damage. Read the kit's parts list.
What is the difference between chain drive and gear drive cams?
Chain-drive cams are turned by a chain from the crankshaft, while gear-drive cams are turned by gears. They need different parts and are not interchangeable without the matching kit, so check which drive your engine has before you order.
What should I check before installing a new camshaft?
Clean the engine, check the lifters, and coat the cam lobes with assembly lube as the maker says. A new cam usually goes with new lifters, because used lifters have worn to the old lobes.
