Dirt Bike Engine
3553 parts
Pistons, top-end kits, gaskets, cylinders, valves, bearings and seals from Vertex, ProX, Wossner, Athena, Cometic, WSM, Boyesen and Moose Offroad. Everything you need for a fresh top end, a full rebuild or a little more power. Shop all dirt bike parts.
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Prox - 01.4342.B - Piston Kit - 76.97 mm - Kawasaki KX250F
Prox
$188.95Prox - 09104543 - Piston Kit - 76.97 mm - Kawasaki KX250FFeaturesPrecision machined on state of the art CNC equipmentMade with low expansion, low friction alloyReplacement Part for OEM...$188.95 -
Prox - 01.3341.A - Piston Kit - 76.96 mm - Suzuki RMZ250 - Fits 2010-2024 Suzuki RM-Z250
Prox
$188.95Prox - 09104539 - Piston Kit - 76.96 mm - Suzuki RMZ250FeaturesPrecision machined on state of the art CNC equipmentMade with low expansion, low friction alloyReplacement Part for OEM...$188.95 -
Pro Circuit - PVK01085 - Power Valve - Kawasaki KX85 '02-'13
Pro Circuit
$229.95Pro Circuit - 09310477 - Power Valve - Kawasaki KX85 '02-'13FeaturesMaintain peak horsepower with huge gains in the bottom endConstructed of billet stainless steelMade in the USASpecs$229.95 -
Prox - 28.SIS3338-2 - Valve and Spring Kit - Intake - Suzuki
Prox
$155.95Prox - 09261461 - Valve and Spring Kit - Intake - SuzukiFeaturesSteel, nitrided valves for increased durability and less wear under extreme conditionsStronger valve springs deal with the extra weight...$155.95 -
Psr - 03-02000-29 - Cam Chain Tensioner - Honda - Fits 2007-2009 Honda CRF150R/RB, 2004-2017 Honda CRF250R/X, 2009-2023 Honda CRF450R, 2004-2009 Husqvarna TE 250-510
PSR
$74.95Psr - 09250786 - Cam Chain Tensioner - HondaFeaturesReplaces OEM automatic/hydraulic tensionerEliminates out-of-timing problems caused by the OEM automatic tensionerEliminates excess...$74.95 -
Prox - 01.6012.A - Piston Kit - 39.46 mm - KTM 50 Adventure/50SX - Fits 2001-2008 KTM 50 SX
Prox
$77.95Prox - 09106102 - Piston Kit - 39.46 mm - KTM 50 Adventure/50SXFeaturesOversized options follow manufacturer piston to cylinder wall clearancesKit includes piston, ring kit, wrist pin, and...$77.95 -
Prox - 01.6012.B - Piston Kit - 39.47 mm - KTM 50 Adventure/50SX
Prox
$77.95Prox - 09106103 - Piston Kit - 39.47 mm - KTM 50 Adventure/50SXFeaturesOversized options follow manufacturer piston to cylinder wall clearancesKit includes piston, ring kit, wrist pin, and...$77.95 -
Prox - 01.6220.A - Piston Kit - 53.94 mm - KTM 125SX - Fits 2001-2006 KTM 125 SX
Prox
$124.95Prox - 09106106 - Piston Kit - 53.94 mm - KTM 125SXFeaturesOversized options follow manufacturer piston to cylinder wall clearancesKit includes piston, ring kit, wrist pin, and circlipsSpecs$124.95 -
Psr - 03-02008-29 - Cam Chain Tensioner - Honda CRF & More
PSR
$74.95Psr - 09251258 - Cam Chain Tensioner - HondaFeaturesReplace OEM automatic/hydraulic tensionerRemove out-of-timing problems, premature engine wear and excess tension caused by an automatic...$74.95 -
Psr - 08-02000-28 - Cam Chain Tensioner - KTM
PSR
$74.95Psr - 09251260 - Cam Chain Tensioner - KTMFeaturesReplace OEM automatic/hydraulic tensionerRemove out-of-timing problems, premature engine wear and excess tension caused by an automatic...$74.95 -
Prox - 01.7411.A - Piston Kit - 94.95 mm - Beta 400RR - Fits 2010-2014 Beta 400 RR 4T
Prox
$216.95Prox - 09106808 - Piston Kit - 94.95 mm - Beta 400RRFeaturesThe piston is precision machined on state of the art CNC equipmentPiston rings are made by OEM factories to exact specificationsSpecs$216.95 -
Prox - 01.2448.A - Piston Kit - 96.95 mm - Yamaha WR450F/YZ450F/YZ450FX - Fits Yamaha 2019-2020 WR450F, 2018-2019 YZ450F, 2018-2020 YZ450FX, 2020-2022 YZ450F, 2021-2023 YZ450FX
Prox
$210.95Prox - 09106781 - Piston Kit - 96.95 mm - Yamaha WR450F/YZ450F/YZ450FXFeaturesThe piston is precision machined on state of the art CNC equipmentPiston rings are made by OEM factories to exact...$210.95 -
Prox - 01.7398.A - Piston Kit - 71.94 mm - Fits Beta 2018-2021 300 RR 2T, 2021-2025 300 RX, 2018-2021 300 Xtrainer
Prox
$221.95Prox - 09106807 - Piston Kit - 71.94 mm - BetaFeaturesCast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close tolerancesKit...$221.95 -
Prox - 01.7355.A - Piston Kit - 87.96 mm - Beta 350RR - Fits 2015-2025 Beta 350 RR 4T
Prox
$221.95Prox - 09106805 - Piston Kit - 87.96 mm - Beta 350RRFeaturesThe piston is precision machined on state of the art CNC equipmentPiston rings are made by OEM factories to exact specificationsSpecs$221.95 -
Prox - 01.7346.A - Piston Kit - 71.94 mm - Sherco 300SE/300SE-R - Fits 2016-2025 Sherco SE/SE-R 300
Prox
$221.95Prox - 09106803 - Piston Kit - 71.94 mm - Sherco 300SE/300SE-RFeaturesCast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close...$221.95 -
Prox - 01.7314.A - Piston Kit - 75.96 mm - Sherco 250SE-F/250SEF-R - Fits 2014-2018 Sherco SEF/SEF R 250
Prox
$209.99Prox - 09106799 - Piston Kit - 75.96 mm - Sherco 250SE-F/250SEF-RFeaturesThe piston is precision machined on state of the art CNC equipmentPiston rings are made by OEM factories to exact...$209.99 -
Prox - 01.6353.A - Piston Kit - 87.96 mm - Gas Gas | Husqvarna | KTM - Fits 2021-2024 Gas Gas EC/EX/MC 350, 2014-2024 Husqvarna FC 350, 2020-2024 Husqvarna FE 350, 2017-2024 Husqvarna FX 350, 2020-2024 KTM 350 EXC-F
Prox
$232.95Prox - 09106793 - Piston Kit - 87.96 mm - Gas Gas | Husqvarna | KTMFeaturesThe piston is precision machined on state of the art CNC equipmentPiston rings are made by OEM factories to exact...$232.95 -
Prox - 01.2232.A - Piston Kit - 53.95 mm - Yamaha YZ125/YZ125X - Fits 2022-2025 Yamaha YZ125/X
Prox
$121.95Prox - 09106780 - Piston Kit - 53.95 mm - Yamaha YZ125/YZ125XFeaturesCast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close...$121.95 -
Prox - 01.1350.A - Piston Kit - 78.97 mm - Honda CRF250R/CRF250RX - Fits 2020-2025 Honda CRF250R/RX
Prox
$188.95Prox - 09106779 - Piston Kit - 78.97 mm - Honda CRF250R/CRF250RXFeaturesThe piston is precision machined on state of the art CNC equipmentPiston rings are made by OEM factories to exact...$188.95 -
Prox - 01.2453.A - Piston Kit - 96.95 mm - Yamaha WR450F/YZ450F/YZ450FX - Fits Yamaha 2024-2025 WR450F, 2023-2025 YZ450F, 2024 YZ450FX
Prox
$221.95Prox - 09106783 - Piston Kit - 96.95 mm - Yamaha WR450F/YZ450F/YZ450FXFeaturesThe piston is precision machined on state of the art CNC equipmentPiston rings are made by OEM factories to exact...$221.95 -
Prox - 01.2450.A - Piston Kit - 96.95 mm - Yamaha WR450F/YZ450F/YZ450FX - Fits 2021-2023 Yamaha WR450F
Prox
$221.95Prox - 09106782 - Piston Kit - 96.95 mm - Yamaha WR450F/YZ450F/YZ450FXFeaturesThe piston is precision machined on state of the art CNC equipmentPiston rings are made by OEM factories to exact...$221.95 -
Prox - 35.7430 - Top End Gasket Set - Fits 2020-2025 Beta 480 RR 4T
Prox
$130.95Prox - 09347793 - Top End Gasket Set - BetaFeaturesManufactured by high quality factories to ProX specifications to ensure top quality sealingSpecs$130.95 -
Prox - 35.7324 - Top End Gasket Set - Fits 2014-2019 Sherco SEF-R 300
Prox
$99.95Prox - 09347786 - Top End Gasket Set - ShercoFeaturesManufactured by high quality factories to ProX specifications to ensure top quality sealingSpecs$99.95 -
Prox - 35.7322 - Top End Gasket Set - Fits Beta 2022-2025 250 RR 2T, 2022-2025 Xtrainer 250 2T
Prox
$62.95Prox - 09347784 - Top End Gasket Set - BetaFeaturesManufactured by high quality factories to ProX specifications to ensure top quality sealingSpecs$62.95 -
Prox - 35.7323 - Top End Gasket Set - Fits Beta 2013-2021 300 RR 2T, 2021-2025 300 RX 2T, 2013-2021 Xtrainer 300 2T
Prox
$62.95Prox - 09347785 - Top End Gasket Set - BetaFeaturesManufactured by high quality factories to ProX specifications to ensure top quality sealingSpecs$62.95 -
Prox - 35.7219 - Top End Gasket Set - Fits 2019-2024 Beta 200 RR
Prox
$51.95Prox - 09347780 - Top End Gasket Set - BetaFeaturesManufactured by high quality factories to ProX specifications to ensure top quality sealingSpecs$51.95 -
Prox - 35.7313 - Top End Gasket Set - Fits Beta 2013-2021 250 RR 2T, 2017-2021 Xtrainer 250 2T
Prox
$62.95Prox - 09347782 - Top End Gasket Set - BetaFeaturesManufactured by high quality factories to ProX specifications to ensure top quality sealingSpecs$62.95 -
Prox - 35.7314 - Top End Gasket Set - Fits 2014-2018 Sherco SE-R 250
Prox
$88.95Prox - 09347783 - Top End Gasket Set - ShercoFeaturesManufactured by high quality factories to ProX specifications to ensure top quality sealingSpecs$88.95 -
Prox - 35.7218 - Top End Gasket Set - Fits 2018-2019 Beta 125 RR 2T
Prox
$51.95Prox - 09347778 - Top End Gasket Set - BetaFeaturesManufactured by high quality factories to ProX specifications to ensure top quality sealingSpecs$51.95 -
Prox - 35.6419 - Top End Gasket Set - Gas Gas/Husqvarna/KTM
Prox
$99.95Prox - 09347776 - Top End Gasket Set - Gas Gas/Husqvarna/KTMFeaturesManufactured by high quality factories to ProX specifications to ensure top quality sealingSpecs$99.95 -
Prox - 35.6347 - Top End Gasket Set - Husqvarna/KTM - Fits 2017-2019 Husqvarna TE/TX 300, 2017-2019 KTM 300 EXC
Prox
$57.95Prox - 09347773 - Top End Gasket Set - Husqvarna/KTMFeaturesManufactured by high quality factories to ProX specifications to ensure top quality sealingSpecs$57.95 -
Prox - 35.6439 - Top End Gasket Set - Gas Gas/Husqvarna/KTM - Fits 2024 Gas Gas EC 500F, 2020-2023 Husqvarna FE 501/s, 2020-2023 Husqvarna FE 450, 2019-2024 KTM 450 XCF-W, 2019-2024 KTM 500 EXC-F
Prox
$99.95Prox - 09347777 - Top End Gasket Set - Gas Gas/Husqvarna/KTMFeaturesManufactured by high quality factories to ProX specifications to ensure top quality sealingSpecs$99.95 -
Prox - 42.7220 - Crankshaft Oil Seal Set - Fits Beta 2020-2024 125 RR 2T, 2019-2024 200 RR 2T
Prox
$22.95Prox - 09351280 - Crankshaft Oil Seal Set - BetaFeaturesAll seals necessary for complete crank rebuild includedSpecs$22.95 -
Prox - 35.1352 - Top End Gasket Set - Fits 2022-2025 Honda CRF250R/RX
Prox
$93.95Prox - 09347760 - Top End Gasket Set - HondaFeaturesManufactured by high quality factories to ProX specifications to ensure top quality sealingSpecs$93.95 -
Prox - 42.7350 - Crankshaft Oil Seal Set - Fits Beta 2011-2025 498/520 RR 4T, 2024-2025 450 RX 4T
Prox
$30.95Prox - 09351281 - Crankshaft Oil Seal Set - BetaFeaturesAll seals necessary for complete crank rebuild includedSpecs$30.95 -
Prox - 42.7218 - Crankshaft Oil Seal Set - Fits 2018-2019 Beta 125 RR 2T
Prox
$22.95Prox - 09351279 - Crankshaft Oil Seal Set - BetaFeaturesAll seals necessary for complete crank rebuild includedSpecs$22.95 -
Prox - 42.4351 - Crankshaft Oil Seal Set - Fits 2021-2024 Kawasaki KX250/X
Prox
$25.95Prox - 09351278 - Crankshaft Oil Seal Set - KawasakiFeaturesAll seals necessary for complete crank rebuild includedSpecs$25.95 -
Prox - 35.7426 - Top End Gasket Set - Fits 2016-2019 Beta 480 RR 4T
Prox
$130.95Prox - 09347792 - Top End Gasket Set - BetaFeaturesManufactured by high quality factories to ProX specifications to ensure top quality sealingSpecs$130.95 -
Prox - 35.7420 - Top End Gasket Set - Fits 2020-2025 Beta 430 RR 4T
Prox
$130.95Prox - 09347791 - Top End Gasket Set - BetaFeaturesManufactured by high quality factories to ProX specifications to ensure top quality sealingSpecs$130.95 -
Prox - 35.7416 - Top End Gasket Set - Fits 2016-2019 Beta 430 RR 4T
Prox
$130.95Prox - 09347790 - Top End Gasket Set - BetaFeaturesManufactured by high quality factories to ProX specifications to ensure top quality sealingSpecs$130.95
Dirt Bike Pistons, Top-End Kits and Engine Rebuild Parts
Every dirt bike engine needs a refresh eventually. Ride long enough and the piston wears, compression drops and the bike just doesn't pull like it used to. Staying on top of top-end maintenance keeps your bike making power and keeps a cheap rebuild from turning into an expensive one.
We carry pistons and complete top-end kits from Vertex, Wossner, ProX and Athena, full gasket sets from Cometic and Athena, plus valves, springs, cam chains, bearings, seals and crank kits for full rebuilds. Boyesen reed valves and engine covers add performance and protection on two-strokes and four-strokes alike.
While the engine is apart, refresh the rest: fresh air filters and carb parts from fuel and intake, oil filters and fluids from oils and chemicals, and repacking or a new pipe from dirt bike exhaust.
Engine parts are specific to make, model, year and sometimes bore size, so check fitment carefully before ordering. If you're not sure what your rebuild needs, send us your bike's details and we'll help put the parts list together.