Valvetrain Component
About Valvetrain Component
The valvetrain is the set of parts that opens and closes the engine's valves at the right instant: the camshaft, the valves, the springs and guides, and the rockers or followers between them. When a timing chain fails, a valve bends, a spring weakens or a guide wears, the engine loses compression, ticks, smokes or refuses to start. Riders shop here for repairs, for a top-end rebuild, or for racing cams and spring kits.
The sub-categories split the job by part. Camshafts holds the cams, whose lobes set when and how far the valves open. Engine Valves lists single intake or exhaust valves and matched valve sets by model and year, with some oversize versions for modified heads. Valve Guides, Springs & Parts covers the guides that keep each valve centered on its seat and the springs that close it, including racing valve spring kits for use with performance cams. Rocker Arms & Parts is the smallest group. New valves go into guides and seats that have been inspected, and the valve clearance is set again once everything is back together.
Brands in this section include Bronco, PSR, ProX, Hot Cams and Shindy. Valve parts are specific to the engine, so pick your machine in the Ride Finder at the top of the page, and see why a part does not fit for how to avoid ordering the wrong one. Head work usually brings in Gaskets, Seals & Kits and Engine Rebuild Kits & Components from the parent group, Engines & Engine Parts.
FAQs on UTV and ATV valvetrain parts
How can I tell if the valves in my ATV or UTV engine are worn or damaged?
Low compression, hard starting, a misfire and a ticking sound are the common signs, though other faults cause them too. A compression test or leak-down test, then a look at the valves and seats once the head is off, will confirm which part has failed.
What is the difference between an intake valve and an exhaust valve?
The intake valve lets the fuel and air mixture in, and the exhaust valve lets burned gas out. Exhaust valves run hotter, and the two are not interchangeable even when they look similar. Make sure the listing says which one you are buying.
Do I need new valve guides and seals when I replace the valves?
Check them. A new valve in a worn guide will wear fast and can let oil past into the engine. The guides, seats and seals are normally inspected during the same job, and the seals are usually replaced. A machine shop can cut the seats.
What does a valve set include?
A valve set is a matched group of valves for one engine, with the model named in the listing, such as TRX450R. How many valves it holds depends on the engine, so read the listing and compare it with the number of valves your engine has.
Do I need to adjust valve clearance after replacing valvetrain parts?
Yes. New valves, a new cam or a refaced seat can all change the clearance. Set it to the figure in your service manual, using feeler gauges, before the engine is closed up and started.
