Engines & Engine Parts
About Engines & Engine Parts
An ATV or UTV engine is a stack of wear parts. The top end, meaning the piston, rings, cylinder and valves, wears with every hour of running, and the bottom end of crankshaft, rod and bearings carries the load behind it. Owners shop here to rebuild a tired engine, to fix one failure such as a leaking gasket or a worn bearing, or to build a bigger-bore setup.
For the top end, start with Pistons, Rings & Piston Kits, Complete Cylinders, Cylinder Heads and Valvetrain Component. The bottom end is Crankshafts, Connecting Rods & Parts, Engine Bearings and Flywheels & Flywheel Parts. When you want the parts for a whole job together, Engine Rebuild Kits & Components lists top end, bottom end and full rebuild kits.
Sealing and upkeep parts are in Gaskets, Seals & Kits, Oil Filters and Oil Drain Plugs, Filler Caps & Dipsticks. Parts for timing and for scheduled service are in Timing Components & Kits and Service Kits. Brackets & Hardware, Engine Covers and Other Engine Parts cover the rest.
Brands in this section include Athena, Vertex, WSM, D.I.D and Bolt. Fit depends on make, model, year and bore size, so pick your machine in the Ride Finder at the top of the page, and follow your manual's clearances and torque figures. The wider catalog is UTV | ATV.
FAQs on UTV and ATV engine parts
What is the difference between a top end and a bottom end rebuild?
A top end rebuild deals with the piston, rings, cylinder, gaskets and often the head and valves. A bottom end rebuild deals with the crankshaft, connecting rod and bearings, which means splitting the crankcase. Which one you need depends on where the wear or damage is.
How do I know what size piston my engine needs?
Piston size follows the cylinder bore. Your manual gives the standard bore and the wear limit, and a bore gauge or micrometer tells you the actual size. If the bore is worn, an oversize piston may be needed. Pick your machine in the Ride Finder and compare the size in the listing.
Which parts should I replace along with the piston and rings?
Replace the top end gaskets, and inspect the cylinder, head, valves and the connecting rod bearing. A piston kit usually has the rings and pin, but check the listing. Fresh oil and a new filter are standard after any engine work.
How can I tell if my engine has worn rings or cylinders?
Signs include smoke, oil use, hard starting and low power. A compression test or leak-down test shows whether the rings, valves or cylinder are leaking. Run it before buying parts, so you replace what is actually worn.
Do I need to break in an engine after a rebuild?
Yes, follow the break-in advice from your manual and the parts maker. Typically it means fresh oil and filter, varying engine speed, avoiding heavy sustained loads for the first hours, and checking for leaks and fastener tightness afterward.
